The Sin of Crank Velocity

Crank and bike speed variations during a pedal stroke

This topic occasionally comes up in discussion in cycling forums – just how much does crank speed vary during a pedal stroke? And how much does this affect the accuracy of power meters?

If you are pedalling along at a steady rate and maintaining a consistent power output (in other words you are not attempting to accelerate or slow down) and are using circular chainrings, then the short answer is: not a lot.

But crank rotational velocity during a pedal stroke is not totally constant, there is some variation.

Of course anyone who has ridden a bike behind a derny or motor pace bike on flat terrain or at a velodrome knows they are able to ride consistently close to the rear guard or roller of the motorbike and not experience significant fore-aft movements during each pedal stroke.

Riders following a motor pacer manage to remain very close
to the pacer and don't experience large fore-aft relative motion.

Riders in a highly skilled team pursuit formation riding at high power outputs are also able to ride within centimetres of the wheel in front without experiencing major changes in velocity between riders during each pedal stroke, which if it did happen would of course be somewhat disastrous. Note the riders below are all at different phases in the pedal stroke:

Track Cycling World Championships 2014: GB women's team pursuit team
Image from: www.telegraph.co.uk

So even without any examination of the research, or doing any fancy modelling of the physics involved, we already know empirically there really isn't going to be large variations in bike and crank velocity.

So how much variation is there and what influences bike and crank speed during a pedal stroke?

When pedalling in a steady state manner, the main factors influencing the variability of crank velocity are:

• The average power being applied
• The manner and level of power variation during a pedal stroke
• The inertial load of the system (i.e. the speed and mass of the bike + rider, plus a little rotational inertia from rotating components)
• The resistance forces in play (i.e. air and rolling resistance, gravity, and changes in kinetic energy) and whether for example air resistance is dominant (e.g. when riding on flat terrain), or overcoming gravity is dominant (e.g. climbing a steep grade)
• The shape of the chainrings, or as in the case of some weirdo bike crank and pedal sets ups, the variable effective radius of the crank arms

Why do we care about crank velocity variation?

Apart from satisfying our curiosity on this somewhat esoteric matter, the answer does have a few practical applications with respect to cycling performance, one of which is to do with power meter accuracy. Others pertain to efforts seeking to eek out minor performance gains though examining mechanical adaptations to the bicycle drive train, such as design of non-circular chainrings. Whether these designs result in a performance improvement is debatable (the research is equivocal on the matter for sustainable aerobic power) and not the topic of this post, so I'll leave it there for now.

Power meter accuracy and crank rotational velocity

Many power meters, e.g. SRM, Quarq, Power2Max, Garmin Vector and Stages, rely on the assumption that crank speed during a pedal stroke does not vary (Powertap on the other hand assumes wheel speed does not vary during their fixed duration torque sampling period of 1 second).

This is an important assumption, since torque is sampled at a fixed frequency (e.g. at 200Hz for an SRM or somewhat lower, e.g. at 50-60Hz for other brands) and then those torque samples are averaged over a complete crank revolution. This averaging of torque over a full revolution to calculate power will only be accurate if the crank velocity does not vary much during the pedal stroke.

If however a rider pedals significantly more slowly during one part of a pedal stroke compared with another, then that slower part of the pedal stroke will be over-weighted in the average of total torque samples. Hence interest in examining the assumption about constant or near constant crank velocity during a pedal stroke.

So let’s look at some of the crank velocity variability factors I mentioned earlier.

Power application during a pedal stroke

It’s well known that when we pedal we apply torque to the cranks in a pulse-like manner, with each leg’s down-stroke moving from a phase of minimal propulsive power when the crank is vertical with the pedal at top dead centre, increasing propulsive force and power as the crank moves down towards the horizontal, and diminishing as the crank moves towards the vertical again with the pedal at bottom dead centre. It looks a little like this:

Image courtesy of:
http://www.rohloff.de/en/company/index.html

In steady state cycling we apply little if any propulsive force on the upstroke and some may in fact apply a little negative force (this is not necessarily a bad thing and is something often misunderstood about pedalling dynamics - but I digress).

This pulse-like power cycle is repeated by the opposite leg and crank arm, so that for each full revolution of the crank, we apply two pulses of power, mostly from the down-stroke push of each leg.

This pulsating nature of power application has been measured and is well reported in the scientific literature, and typically shows a wave-like sinusoidal pattern (i.e. it looks like a sine wave), which should come as no surprise given our legs act like two pistons pushing down on rotating crank arms.

Studies examining this go back many, many decades, e.g. this 1968 paper by Hoet at al as an example reported the following finding:

Those summary findings by Hoes et al have been consistently replicated in many subsequent studies.

Such analysis goes back even further, to the late 1800s. Pedal pressure was measured and shown in this book: Sharp, A. (1896). Bicycles and tricycles: an elementary treatise on their design and construction.

This fabulous old book (which covers a huge range of cycling physics and performance matters over 32 chapters and which Lee Childers at Alabama State University kindly referred me to) is available in scanned form online here:

https://archive.org/details/bicyclestricycl02shargoog

Here are image scans from four of the book's 561 pages showing pedal pressure measurements from various riding conditions on a fixed gear bicycle (flat track riding, ascending and even back pedalling when descending). Read from the bottom of page 268 - Section titled: 214 - Actual Pressure on Pedals.

The charts plot the measured pedal pressure, which is not the same as the tangential (propulsive) forces, a point made on page 270 - but even so we can see the basic shape of pedal forces follows this basic pattern. Indeed Sharp refers to such tangential pedal force measurement pedals designed by Mallard and Bardon, their "dynamometric pedals". I don't have a link to show these unfortunately. This was the late 1800s. What's old is new again.

Below is an image from the 1991 Coyle et al paper showing the measured crank torque applied by one leg through a full pedal stroke for each of the 15 riders in the study. We don’t need to inspect the plots too closely; the main point is we can readily see the approximately sinusoidal shape of torque applied to the cranks during the down-stroke phase, and the minimal torque applied during the upstroke phase.

The primary differences between riders are in the amplitude of the down-stroke phase of curve, and the shape of the upstroke phase, which mostly hovers around the zero line. As always, you can click on an image to see a larger version.

If you then imagine the opposite leg repeating the same type of torque application, then we can see we apply torque to the cranks in a pulsating wave-like, or sinusoidal, manner. This sinusoidal curve was also demonstrated in the 2007 Edwards et al paper which included the following plot of typical pedal torque applied by both legs for a full crank revolution:

So while not perfect sine wave-like application of torque, thinking of the force applied to the cranks as being sinusoidal-like is a very good first order approximation.

Users of indoor bike training systems like Computrainer, Wattbike or SRM's Torque Analysis System may have also seen similar torque output curves. Here’s a random example of an image of a Computrainer SpinScan plot I found with a quick Google search:

Now SpinScan is not as fine a resolution measurement tool as used in scientific study, but at least you can see that the same basic shape of the power output curve during a pedal stroke. Wattbike charts are typically displayed in polar chart format, so to avoid confusing things I won’t post a picture here but the same overall pattern of torque and power application is repeated, as they are with SRM's Torque Analysis system (although this is a very low power example from SRM's website):

One thing we can see with all these examples is how power doesn't generally drop all the way to zero while pedalling, and that it is often not symmetrical for left and right legs.

I have generated a sample sinusoidal power curve to reasonably approximate this pedal power pattern which I'll use for modelling I'll discuss later on. In this case it shows the power curve when pedalling with an average power of 250 watts at 90rpm (click on pic to see larger version):

Now this is by no means a perfect model of actual power application, and as can be seen from the various charts shown earlier, everyone pedals slightly differently, but it’s certainly a very good first order approximation to examine the issue of how much bike speed is affected by application of such a pulsating power curve. It matches the general shape of actual torque delivery delivery and the peak power is nearly double the average power, which also matches the torque profile measured experimentally many times, and at least since Hoet at al reported this in the 1960s.

Naturally the power curve is a function of both crank torque and crank velocity, but as we shall eventually see, the latter does not vary all that much, certainly not enough to make this first order approximation invalid for the purpose of answering this question.

So what effect does this pulsating variable power output have on bike and crank velocity?

Firstly I’ll look at an example of what’s actually been measured and reported in the scientific literature, and then I’ll examine the physics with some modelling.

Actual measurement of crank speed variations

Crank speed variations during a pedal stroke were reported in this paper by Tomoki Kitawaki & Hisao Oka: A measurement system for the bicycle crank angle using a wireless motion sensor attached to the crank arm, J Sci Cycling. Vol. 2(2), 13-19.

Here’s a link to a pdf of the paper I found in a Google search:
http://tinyurl.com/qapfoek

I'm referring to this paper in particular as it provides some helpful images and a full version is available online for anyone interested in examining it in more detail. Other studies have also measured crank velocity during pedalling and found similar results, but the data may not be available in the freely available public domain nor presented in such a convenient and helpful manner as needed for this discsussion.

Figure 6 of this study (shown below) summarises the measured variability in crank velocity over a range of power outputs for riders in three groups categorised as beginner, intermediate and expert level by their relative power to weight ratio being approximately 1.5W/kg, 2.25W/kg and 3W/kg respectively.

Crank velocity for each group is shown at two different cadences (70rpm and 100rpm) and was measured using two different crank velocity measurement systems (the study was primarily to examine the validity of a crank angle and velocity measurement system compared with a standard. As it turns out the two methods matched quite well). They also measured the crank velocity variations at the riders’ freely chosen cadence but did not provide charts for those data.

In this study, riders used their own bike on a CycleOps Powerbeam Pro trainer, which is a fairly typical and relatively low inertia indoor trainer.

It shows six charts. In each the crank rotational velocity relative to the average crank rotational velocity (i.e. the normalized crank rotational velocity) is plotted by crank angle for a complete pedal stroke. There are a series of dots and lines plotted in the charts, and these represent the normalized crank rotational velocity as measured using two different measurement systems.

The maximal variance in normalized crank rotational velocity occurs in the most powerful group of riders, and at the lowest pedal rate (70rpm). The variance in this case was around +/-3% and in all other cases the crank velocity variance was less than +/-2%.

Keep in mind this experiment was performed on a low inertia trainer. Why does this matter? 

It matters because a mechanical system (or an object) with lower inertial load will accelerate (or decelerate) more rapidly when a net force is applied to it compared with a system with greater initial inertial load. Many indoor trainers, like the Powerbeam Pro used in this study, have lower crank inertial loads for the same rear wheel speed compared with what a bike and rider riding out on the road typically possesses.

So what happens when we examine the case of a more realistic road-like inertial load scenario?

Since I’m unaware of published and validated crank velocity measurements readily available from actual on road riding (if anyone can point me to any please let me know), we can instead examine the physics of what happens to a bike’s speed when power is applied in this pulsing sinusoidal-like manner.

Forward integration - Balance sheet accounting for energy

To do that I use the technique of forward integration, a technique that’s really no more complicated than an accounting balance sheet but for energy rather than money.

On one side of the balance sheet is the energy supply coming via our legs, and the other side of the balance sheet is the energy demand, i.e. the power required to overcome various resistance forces such as air resistance, rolling resistance, gravity if changing height, and importantly resistance to changes in speed (kinetic energy). That energy balance sheet must remain in balance. It’s a fundamental law of nature.

At any point in time if we know a rider’s speed, their mass and that of their bike, the moment of inertia of their wheels, their coefficients of air and rolling resistance, the road gradient, and other small frictional loss factors, then we can calculate how much power is required for each of these various resistance forces, and when added together they tell us how much power is required to maintain that speed.

If a rider’s actual power output is different to that required to maintain the same speed, then the balance of power supply must result in a change in kinetic energy, and hence a change in speed.

If a rider is in deficit on the energy balance, then that deficit must come from somewhere and that means their kinetic energy (and hence speed) must reduce by the same amount accordingly. Put another way, they are not supplying sufficient power to maintain their original speed and must therefore slow down.

Conversely, if the rider is providing power in excess of that required to maintain their original speed then they will accelerate, and at a rate so that the increase in kinetic energy matches that energy surplus.

In the model these calculations are made for each brief moment in time, the net energy surplus or deficit for that initial speed is determined and converted to the exact change in speed required to maintain the energy balance.

Let’s examine what happens to a rider’s speed in a sample scenario.
250W, flat road @ 90rpm

Riding along at 90rpm on a dead flat road with no wind and with an average power of 250W at around 36km/h with:

• Bike + rider mass: 80kg (including wheel rim mass of 1kg)
• Coefficient of rolling resistance (Crr) of 0.005 (fairly typical for good road tyres on asphalt/chip seal surface)
• Coefficient of drag area (CdA) of 0.35m^2 (e.g. road bike on the hoods)
• Air density of 1.20kg/m^3 (sea level, 1020hPa, temp 21C, relative humidity 77%)
• Drivetrain efficiency:  100% (just to keep it simple, although ~97% is typical)

Using the forward integration model with the simulated sinusoidal-like power output during a pedal stroke, we can now plot the impact on bike speed during a pedal stroke. Click to view a larger image.

In the chart above we have the power output (yellow line) varying during the pedal stroke, which takes a total of 0.667 seconds to complete each revolution. The plot show 1 full second of pedalling, and so the graph actually shows one and half revolutions of the crank.

The initial velocity is set to a little under 36km/h. The speed resulting from that pulse like power input is also plotted by the blue line with the left hand axis being speed. Note the speed scale ranges from 24km/h to 40km/h and so is already zoomed in a little to amplify the variation. At that slightly zoomed scale we can see that the speed line wavers up and down just a little during the pedal stroke.

Since it’s a little hard to see how much variation in speed happens, let’s zoom in much more by adjusting the speed scale to amplify that speed variation curve.

Note the scale of the speed axis on the left side – each horizontal grid-line represents 0.05km/h, and the variation in speed is easier to see.

When power is higher than that required to maintain a constant speed, then speed increases. Eventually though the power drops below the level required to keep accelerating, and speed levels off then begins to decline as power has dropped such that there is now an energy deficit compared with that required to maintain that speed, and so kinetic energy (speed) must fall. As a result, the speed plot follows a similar sinusoidal-like curve, but out of phase with the power plot.

Here’s a table summarising the average, minimum, maximum and amount of variation in power and speed.

The normalized speed variation is less than +/-0.2%.

As I said, not a lot of variation in bike speeds during a pedal stroke, even though the power is ranging from a low of 20W up to a maximum of 480W twice each pedal stroke.

That's bike speed - what about crank velocity?

Now the next logical step is to assume that this “all-but” constant bike speed is also matched by constancy of chain speed and hence crank speed. Since the chain is moving around the rear wheel's circular cog and the upper drive section of the chain has positive tension then that is what you would expect.

So provided the front chainring is circular, this will also result in a nearly uniform crank rotational velocity.

Hence in this steady state cycling scenario we need not be concerned with any inaccuracies in power measurement due to the assumption used by power meters that crank velocity is constant during a pedal stroke.

For crank velocity not to closely match the bike’s velocity it would require the part of the chain under constant tension to stretch and contract significantly during each half pedal stroke, or for the chainring to not be circular. Chains just don’t do that but chainrings may be all sorts of curved shapes.

Sensitivities and assumptions

As I said earlier, this input power model is only a first order approximation; people apply power slightly differently, and not necessarily symmetrically or consistently. Some of the other assumptions may not necessarily hold, e.g. aerodynamic and rolling resistance coefficients, and drivetrain efficiency remaining constant during a pedal stroke when they may in fact vary a little during pedal stroke. The rider’s legs also slightly vary their kinetic and potential energy as they move through a pedal stroke,

These are second and third order effects that would only make minor changes to the shape of the modelled speed curve, and we can see that the speed variation is already so small such that second and third order modifications are not going to change the outcome to any significant degree.

What about when climbing a steep hill?

When climbing, average speed for same power will be significantly less than when on a flat road. On an 8% gradient our 250W rider will be travelling at closer to 13km/h instead of 36km/h. That’s means a much reduced kinetic energy – which is dominated by translational KE of the rider.

KE = 0.5*mass*velocity^2,  plus a little bit from wheel rotational inertia (which is very small).

The translational KE of our 80kg bike and rider at 36km/h is 4,000 joules, and at 13km/h it’s 522 joules, or only 13% of the KE at 36km/h, even though velocity is 36% of flat road speed.

The next big difference is the resistance forces are now dominated by overcoming gravity rather than overcoming air resistance. This also has an impact on the size of bike speed variations during a pedal stroke, the result being we should expect changes in speed to be greater.

Finally, many riders have a tendency to pedal at a lower cadence when climbing steep hills. Not everyone does of course, but sometimes the available gearing means a lower cadence is inevitable. So for the sake of this scenario, let’s assume the rider’s cadence has dropped to 60rpm (that's about what cadence would be with a 39x23 gear at 13km/h).

This is the power and speed plot:

Since the cadence is 60rpm, it take a full second for each pedal revolution. We can see even with the low zoom level on the speed axis that the bike’s speed line does indeed vary more than when on the flat road.

Here’s what the speed variation looks like using the same zoomed-in view setting as before:

So when climbing there is a much greater variation in bike speed during a pedal revolution than when riding on a flat road at higher speed, but it’s still less than +/-2%.

Is a +/-2% crank speed variance during a pedal stroke something to be concerned with for power meter accuracy? 

As a rough rule of thumb, the error this would introduce to the calculation of power would be approximately 40% of the crank speed variation, or less than 1%. Whether that 1% error matters to you I can't really say, but it's a couple of watts and for most people it's not a significant factor for the purposes they might be using power meter data from climbs for.

If you are doing some aerodynamic field testing though, then such an error would be of concern. Fortunately we don't do such testing on steep climbs all that much, but rather mostly on flatter terrain where any error due to crank rotational velocity variation as we have seen is tiny.

That’s a 3.5W/kg rider. What about a more powerful 5.5W/kg rider climbing that 8% grade?

More powerful riders climb faster, and likely pedal at a higher cadence as well, so let’s assume our 400W rider climbs the 8% grade and pedals at 75rpm (that's roughly the cadence if pedalling a 39x19 gear at 19 km/h). This is the resulting power and speed plots:

So even though the rider is more powerful and has much greater variation in power output, the increased cadence and higher speed means the normalized crank rotational velocity variation is only +/-1%, and power meter error is likely to be less than 0.4%.

Summary

While pedalling in a steady state manner out on the road with circular chainrings, crank speed does not vary all that much. It varies more when climbing than when riding along flatter terrain, but the amount of variation is still small such that the basic assumption of non-varying crank velocity used by power meters to calculate power is sufficiently valid and within their generally stated margins of error.

Crank speed variation is larger when riding on low inertia trainers, such that the level of potential error in reported power may begin to approach the limit of the devices' stated error margins.

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HOP to it!

Quite a few years ago (circa 2002), I learned of an indoor workout called "The Hour of Power" or HOP for short. It was coined by Bill Black, a regular contributor to the Google Wattage Groups forum. The workout also features in the book, Training and Racing with a Power Meter.

It's a pretty simple style of workout, designed to lift your power at threshold as well as provide a bit of a neuromuscular twist. Indeed any solid tempo effort at this level is very good for helping to lift one's threshold power. They are not easy workouts and can be quite fatiguing, so it does help to build up to doing them if you haven't been riding much lately.

There have a been a few different formats but the basic theme is the same:

Ride at a base load that is sub-threshold (~90% of your 1-hr maximal power) and every few minutes do a surge for about 15-seconds or so. Doing this mixes up the workout and does help to make the time pass a little more quickly.

Since today I was planning on a 90-minute solid tempo ride, and it was raining outside, I decided to do my workout indoors on Thunderbird 7 and thought, you know I've never actually had a go at the HOP. So that was today's mission.

Actually I ended up doing what you might call HOP+, since I did want to do 90-min of tempo, rather than the hour. So I decided to do a HOP, then assuming all was well would finish off the workout with some more tempo. This is what eventuated:


This is the picture of the workout data (click on it to see a larger version). The two horizontal dashed lines mark my Funtional Threshold Power (FTP) and 90% of my FTP. Plotted are my power output (yellow) and cadence (green). The boxes show the stats for the HOP and for the tempo effort that followed.

After I finished the HOP, I "hopped" off T7 to do the usual remove leg and liner, dry down and replace before getting back on for the final 30-min of tempo riding.

An interesting personal observation was as the workout progressed, I seemed to get better. The tempo at the end was taxing but not a killer by any measure. No doubt it won't be like that everytime I do it.

All up, a really good quality session. You should give a go one day.

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Quadrant Analysis

Earlier I posted about a thought I had - to do a Quadrant Analysis (QA) on the power meter data from my Threshold Tolerance Intervals (TTIs), comparing TTIs done at my local training ground, Centennial Park Sydney, to TTIs done on my home trainer, Thunderbird 7.

Funny, in the several years I've been posting about power meter stuff, I haven't mentioned QA. Yet it is one many funky tools to help explain some the differences in the physiological demands of different types of rides.

I don't really have to go into much detail to explain it, since it's already been done by Dr Andrew Coggan and you can read all about it here.

But the short version is that QA is useful for examining the neuromuscular demands of a ride. Essentially it plots pedal forces versus pedal speed (the combination of both equaling power) for each data point recorded by the power meter. In this way, we can not only see how much power we produced during a ride but also gain additional insight into how we produced that power.

There are a number of ways such a plot can be used (e.g. examining and/or comparing ride data with your maximal pedal force-pedal velocity relationship) but I'll leave that for another day.


OK, so the plot is shown above. Let me run you through it:

- The vertical axis is Average Effective Pedal Force (AEPF - measured in Newtons)

- The horizontal axis is Circumferential Pedal Speed (CPV - measured in metres per second)

- Plotted in little red and blue dots/circles are the AEPF and CPV for each second of power recorded by the power meter. The data is from the "on" parts of my intervals only, that is just the time I spent at the intended effort. There is 40-minutes of data for each group.

- The green curved line shows the point at which pedal forces and pedal speeds, when combined, equal my Functional Threshold Power.

- the vertical and horizonal purple lines delineates the quadrants and represent 90rpm (with a 175mm crank) and 167 Newtons (or the same as applying a force of ~ 17kg).

The four quadrants represent:
I - high pedal speed & high force (e.g. sprinting at high speed)
II - low pedal speed & high force (e.g. hard efforts, such at track starts)
III - low pedal speed &low force (e.g. just noodling along at low rpm)
IV - high pedal speed & low force (e.g. spinning fast but easy downhill)

We plot AEPF and CPV, since from a neuromuscular point of view, what's important is both the force and speed of muscle constractions/movement. Investigating either AEPF or CPV in isolation from the other is a fairly pointless exercise. (Refer Pithy Power Proverb "Cadence is a Red Herring" - R. Chung).

We can only plot AEPF, since each point of power meter data covers one or more revolutions of the cranks, in other words, the average of the forces applied to the pedal for an entire rotation of the crank. What this doesn't show is the variability in forces applied around the various points in the crank's revolution. As we know though, the greatest forces are applied on the downstroke, and by a happy coincidence, the maximal force exerted on the downstroke by each leg is roughly double the AEPF*.

* post edit: it was pointed out to me by Robert Chung I had expressed this relationship incorrectly (I had said "the maximal force exerted by one leg is the roughly the same as AEPF") and made this correction to show what I originally said as well as what it should have said.

CPV is basically similar to pedalling cadence, so why don't I just show cadence instead, since most people can related to what 90 rpm is like? Well in this case, the crank length on each bike is different. On the road bike I have 175mm cranks and on T7 I have 170mm cranks. So at the same cadence, the CPV would be higher on the bike with longer cranks. Or for the same CPV, my cadence would be slower on the bike with longer cranks.

If however you were examining ride data from rides using the same length cranks, then certainly you could also show cadence.

OK, so what do we make of the plots of my TTIs?

Well the first thing is that the dots are quite tighly grouped near the centre of the chart, which is pretty typical for efforts of a time trial nature. Generally the flatter the terrain, the more tightly grouped the dots will appear for a quasi-steady state effort. This contrasts significantly to plots for track races, criteriums and rides over hillier terrain, where the dots are widely scattered around the chart. In rides like MTB, the technical nature of riding can see a rider bumping up towards their maximal AEPF-CPV curve quite frequently.

The next thing is how much more tightly grouped the blue dots (indoor trainer) are compared to the red dots from the outdoor ride in the park. This shows that while the average power from these efforts was very similar, there were still differences in how I produced that power in each case.

We can see that the dots are close the the green line (denoting a pedal force/speed combination at FTP) and that the effort, overall on average, was just below my FTP.

The red dots tend to parallel the shape of the green line, which is reflective of me seeking to maintain power within a desired band over slightly variable terrain (I think the total altitude change is ~ 16-18 metres over the course of a 3.8km loop, with a few ups 'n' downs along the way). My speed varied significantly with the terrain and my cadence varied as well, although not by as much as speed since I would change gear regularly.

So, when riding on a trainer, there is a tendency for the AEPF-CPV relationship to show more of a rifle like plot during such Threshold Tolerance effort, whereas outdoors on more variable terrain (and conditions) the plot looks a little more like it came from a shotgun, albeit it one with an odd shaped barrel!

Is it important?

Well it simply serves to show that similar efforts can have variable neuromuscular demands and even changes as small as this may affect the power one is capable of producing in a given scenario. It just emphasises the specificity principle.

If your time trials are outdoors, makes sure you do some time trial training outdoors and ensure your legs are ready for the more variable neuromuscular demands.

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Smith & Wesson

The indoor training Gods have spoken.

This morning was meant to be my Threshold Tolerance Intervals (TTIs) - the good ol' 2 x 20-min workout at near FTP. Target range at the moment for me is 91-96% of FTP (250-265W).

So I drive to park today, hop out to attach my leg and get bike ready, Sam was riding past and sees me so stops to say hello. I get my leg on and roll off, intending do a roll for a lap or two with Sam before getting into it. But of course after 3-min a spoke goes "ping" and that's was it, wheel not in a trainable condition unfortunately. Hop back in car and go home.

So I hop onto Thunderbird 7 instead.

Last week I did my TTIs in the park at 259W and 255W.
On T7 this morning: 258W and 266W.

I intend to do a Quadrant Analysis plot of the indoor vs. outdoor TTIs and post about that soon. I suspect we'll see the difference akin to the mark on a target made by a rifle and a gunshot.

Read More......

Turbocharged Training

There's been a bit of discussion lately on various training forums about a topic that seems to crop up every so often. It's a perennial favourite. Certainly I'm not the first to write about it and I won't be the last.

Why is my power different when training indoors* compared to when I ride outside? And what can I do about it?

* Indoor training being training done on an ergobike, or with the bike locked into a turbo trainer or riding your bike on rollers. Often performed inside the house, in the garden shed or garage, on a balcony or at the local gym or training centre.

Usually people train in such a fashion because they either haven't the time or opportunity for a ride outdoors, they might be recovering from injury and/or need the controlled and safe environment an indoor trainer provides, or the riding conditions outside are not suitable (cold, rain, snow, darkness and so on). Certainly riding indoors is a safe and excellent training alternative when heading out the front door on your favourite steed is not possible.

For many riders though, they find generating power indoors much harder than when riding outdoors and end up riding at a lower power as that's all they can do (but this is not the case for all though, and some can actually produce more power indoors than outside, although that is less common).

So if I can't generate the same power, then am I getting the same training benefit?

And if power is significantly different indoors, should I use a different FTP for indoor rides (so training levels and ride data are adjusted accordingly)?

Well the answers are not straightforward but let's explore the solution(s).

The first thing to do is to understand why a difference in power production exists. Then the second thing is to take steps to address the differences between each scenario and "bridge the gap". Finally, one then needs to make decisions about how the data from their indoor training should be interpreted.

So why is it common for power to be different?

There are four main factors at play here:

• Cooling & air flow
• Inertial load
• Motivation
• Adaptation

I'll explore each of those in a bit more depth a bit further down.

OK, so what about the training benefit and setting of FTP?

Well power is power and if you are burning kJ at a lower rate, then the metabolic adaptations relating to that will be correspondingly different. So if turning out a lower power really concerns you, then the priority is to address the factors that influence indoor power production and reduce the gap so that training can still be done within the intended training level. Then the problem goes away.

Nevertheless, "hard is hard" and "alls you can do is alls you can do", so if you are unable to address/fix the key reasons why power is less indoors, then set your training at a level that is attainable for that scenario. It's better than staying on the couch. Rather than worry about what percentage of FTP or MAP that should be, just use previous indoor workouts as your guide. That really should be the guide anyway, irrespective of mode of training you are doing.

What matters is that you do the workout at around the right intensity for the right duration, rather than the precise wattage.

What about FTP, and the calculation of TSS and the other metrics that flow from it?

This really is an issue of what you are training for and where the majority of your riding will be during the course of that training period. If the trainer only represents a minority of your ride time and your power is say 10% less on the trainer, then it only represents a small difference in the calculation of overall training load. It is simply not worth the bother to have separate FTP values and calculations. The Impulse-Response model (aka the Performance Manager and the metrics CTL, ATL and TSB) is fairly robust. It is about the forest, not the trees.

For example, let's examine a common hour-long training ride and say, for whatever reason, your indoor power is 10% less than outdoors: 2 x 20-min at FTP + warm up and cool down.

Outdoors, this would accumulate ~ 85 TSS and indoors (with ~10% less power), ~ 70 TSS. A difference of 15 TSS (which is about the equivalent stress of 15 minutes of endurance level riding).

So if the difference in TSS calculated from a 2x20 workout (equivalent to about 15-minutes of basic endurance level riding) is concerning you, then sit on the trainer for another 15-minutes.

If however, the trainer represents (for that training period) a large proportion of your training time, then setting FTP according to that training mode makes sense. But where such rides are only occasional, then there really is no reason to worry about minor variations in the numbers, just move onto the next day.

The same principles apply if talking about training at altitude (occasional change in altitude vs. a lengthly block at a different altitude) or different bikes (occasional or lengthly training blocks on a given bike/position).

Read on for more details on the four elements of indoor training that affect our ability to produce power indoors and how you might do something about it.


Cooling
People consistently underestimate the cooling needs when training indoors. There's some weird theory that a large pool of sweat forming beneath you is a good thing. All that tells me is that the air flow and cooling arrangement is perhaps inadequate for the task. A body that is under stress and not being adequately cooled will underperform.

Keep in mind that the typical cyclist operates at around 21-22% efficiency (give or take a couple of percentage points). Cycling efficiency is a measure of the ratio of energy reaching the cranks of the bicycle as a proportion of the total energy metabolised*.  In other words, to generate 100W at the cranks, our bodies are metabolising energy at the rate of 100W / 21.5%  = 465W.  

So of that 465W, 100W is converted to mechanical energy at the cranks, with the vast majority of the balance being converted to (waste) heat, with a bit used of course to run the rest of the body's functions.

What that means is that for every 100W we put through the cranks, roughly another 360W are generated as waste heat. How much heat exactly will vary depending on the individual's efficiency level (typical range is 19-24%).

So if for instance you are doing some intervals at 300W, you are in effect pumping out the heat equivalent of a 1,000-1,200W electric heater!  Now do you see why we heat up so quickly when training hard and an effective cooling system is required?  Especially if the ambient temperature is quite warm to begin with, and particularly so if the conditions are humid.

When you hop on your bike for an endurance ride, you have a ~ 30km/h wind flowing over your whole body constantly wicking sweat away and keeping you cool(er). So why would you expect to perform as well indoors with no air flow, or the piddling excuse of a breeze that comes from a domestic fan? Get real. If training indoors is going to become a sizeable chunk of your training time, then get some decent cooling happening and have some strong air flow over you. A large industrial strength fan costs much less than a trainer or rollers, so bite the bullet and sort it. But be prepared for the additional noise.


Some people do perform indoor training in quite cold environments, so of course they might be able to get away with less air flow than others.

* there are a couple of different efficiency measures (e.g. gross and delta efficiency), but for all intents and purposes, this basic definition will suffice in this context.


Inertial load is the next main differential factor when comparing indoor and outdoor training. Without going into too much detail, when we ride outdoors, we have the inertial load of a bike and rider moving at some speed, plus that of the wheels turning. If we stopped pedaling, our rear wheel doesn't suddenly slow or stop turning, we would coast for quite some time. On many trainers however, since we are not moving, the inertial load is much less and confined to the rear wheel spinning and any small flywheel that the trainer has attached to the roller. When you stop pedaling, the wheel slows and comes to a halt relatively quickly. Some are worse than others.

Now what happens is each scenario feels quite different to ride, muscle activation is different, the neuromuscular demands are different and these can be enough for some to make power production much harder. In general, low inertial load trainers tends to emphasise the "dead spots" in the pedal stroke (when the cranks are passing through the 12/6 O'Clock position), whereas riding with a higher inertial load enables one to breeze through (and not waste effort on) the dead spots and focus on the downstroke where the bulk of power is produced.

Fortunately there is a way to increase the inertial load of a trainer, and that's by having a flywheel attached to the trainer's roller (or even by adding mass to the wheel itself). How much mass is needed? Well to replicate the inertial load of a rider, it would need a very heavy flywheel spinning very quickly. Think of a 20-30kg flywheel spinning at 500-800 rpm. Yikes!!


Fortunately, for effective training, going that far is not really necessary and having enough rotating mass to help smooth out those dead spots is enough. I don't have one myself but trainers like the Kurt Kinetic Road Machine or the 1-Up trainer are an excellent example of this. They both have small but effective flywheels attached to the rolling mechanism.

These are ideal options for those that are looking to attach their existing bike to a trainer but also need some portability with their indoor unit.

The other option is a dedicated ergobike like the Schwinn or Saris indoor trainers (or other similar machines). These types of set up have the advantage of being able to incorporate a much larger and heavier flywheel than a turbo trainer. They are of course dedicated units and need a permanent place to live.





















So what does one do? Well if cooling has been sorted, and power is still down, then consider the inertial load of your trainer set up. Does it have a flywheel? Can one be added? Should I look at an alternative trainer? Certainly I would recommend trying a trainer that has a decent flywheel to see how much better it is to ride.Edit note: I added the following paragraph in March 2011 as something I'd been meaning to do for quite some time, just had forgotten to do it.
I should add that the idea of inertial load on an indoor trainer affecting pedaling isn't actually backed by evidence other than anecdotal, from myself and many others I know that have used such trainers. As an example, this link to a study extract on PubMed indicates that varying crank inertial loads has little or no effect on steady state pedaling coordination.


Motivation is a big issue in training and racing, and it is sorely tested when riding indoors. Many find training indoors mind-numbingly, excrutiatingly boring. Then there are others who really love it and are happy to spend hours tapping it out, sometimes preferring that to a ride outdoors. Each to their own.

If a lack of motivation is an issue, then it needs to be addressed, otherwise don't waste your money on a trainer you won't use. It'll just end up gathering dust in the corner of the shed.

There are many ways to overcome any motivational challenges you face:

Variety - there are lots of training workouts available, so keep the variety up. Dream up some of your own!

Duration - indoor riding is hard work, there's no let up or coasting, so don't make the workouts as long as you might ride outdoors. It is better to complete a shorter workout and want to come back for more next time, than to get off absolutely hating it and sitting out the next one on the couch or staying in bed.

Set Challenges - set yourself targets for the session and maybe have reminders of your goal event in front of you as well.

Music - this is a good one - having you favourite training tunes blasting away, or on your iPod to keep the neighbours happy.

Video - what about watching highlights of your favourite stage race or one-day classic. You can be smacking it up Ventoux with the Pros. Of course there is a big market out there for indoor cycle training videos, so if that floats your boat, then go for it!

Computer aids - there are lots and some of the favourites are heart rate monitors, spped and cadence measurement computers and of course my favourite - power meters. These are especially helpful so that training is focussed and performed at the right intensity.

Ergo controllers and virtual riding - there are many trainers that can automatically control the resistance level of the trainer and be pre-programmed to control a workout. Some can even display video of an animated figure or some real life video to provide a distraction from the effort and help to pass the time.

Of course the most obvious answer is simply to HTFU.


Adaptation is the last of the four key issues. Since there are differences in riding on a trainer to riding outdoors, some of which have been discussed already, then it stands to reason it will take some time for the body to adapt to training under different conditions. If you only ride the trainer occasionally, then you may never fully adapt to being able to generate power similar to outdoor riding.

However, if you ride on a trainer regularly and with sufficient volume, and you address the other three main factors, then you will adapt and improve your ability to produce power indoors and the gap to outdoor power will typically narrow.

What do I do?

Well I set about addressing all of the issues and descibe my indoor training set up here:
Turbocharged Training Thread on TT Forum

Have fun indoors!

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Swiss Watch

"The body responds like a Swiss watch. You just have to figure out how to wind it." - Dave Harris

OK, alright, I got a complaint about my blog. Like, "you haven't posted anything for ages!". Well it's been twenty days to be precise, but who's counting?

I've just been busy with quite a few things, so I'll try a catch up with this post.

Since my benefit night, training has continued along very nicely. In the first three weeks of December I have accumulated a little over 21 hours of riding and 1457 TSS with an average Intensity Factor of 0.83. That means that those hours, on average, were ridden at a level of exertion of 83% of my estimated 1-hour maximal (threshold) power.

Which is a technical way of saying very little training time has been wasted, and all efforts have been quality. Training has basically been a mixture of core endurance rides, solid tempo efforts, threshold tolerance intervals along with some track sprint work.

Here is a pic of the "thin blue line" to date:



Again, you can see the steady progression of the chronic training load (blue line) indicating the continual progressive increase in load/stress being placed on my body. The leg has been holding up well to the increase in workload and the body is also continuing to adapt. How well is it coping though?

Last week I was scheduled to do some performance tests, one a time trial effort of around 16km (10-miles) and the other a Maximal Aerobic Power (MAP) test. While not a formal test, I have also been doing some sprint work at the track to see how my maximal (neuromuscular) power is going.

First up was my time trial at Centennial Park. Here's the power file chart:



An average power of 287 watts over 26 minutes. So TT power is up 39 watts (nearly 16%) on the test I did on 23 September.

I sometimes surprise even myself. That's 9 watts more than same test/venue (albeit on a cold day) on 8 Aug 2006. I was a few kg lighter back then though. For reference, my best power on that course is 328W (and at a lighter body mass as well).

I followed that up with the MAP test on Friday, riding Thunderbird 7 (my indoor trainer bike). Here's the graph:



My MAP was 385 watts (mean maximal 1-minute power during the test). Yikes! That's up 30W (8.5%) on my last MAP test on 25 September.

What's even scarier is that's only 14W shy of my best ever MAP of 399W (as measured by Powertap on a Computrainer). Allowing for some drivetrain power losses for recording with Powertap vs SRM, that still means my MAP has attained nearly 95% of pre-accident levels. That is pretty remarkable under the circumstances. It's only six months since I put the bike into a home trainer and tried to pedal.

What about my sprints?

Well for a couple of Sundays now I have gone to my local track for some sprint work. I am now getting peak power > 1200W on several occasions. Pre-accident, I would regularly be ~ 1350W and occasionally up to 1400W. So sprint power is not too bad either.

So my body is indeed a Swiss Watch. It seems that coach has worked out how to wind it quite nicely!

Of course one of the consequences of that testing is my estimated Functional Threshold Power has gone up from 240W to 275W. Since my daily training stress is calculated relative to FTP, it means that rides have to be at a higher power now to earn the same Training Stress Score.

As they say, it doesn't get easier, you just go faster.

This morning I woke late, and then checked what was on the program today. 2.5hrs, that's what! Holy smoke! OK, so I saddle up, head out the front door and get into it doing a run to Kurnell, being my first proper solo run back out there in the world of Sydney's roads.

A little over 2.5 hours ride time later I get home, with two short stops along the way to remove, dry and replace my leg liner which seems to accumulate the contents of Sydney Harbour while I'm riding.

Average Power: 186W
Normalised Power: 198W
TSS: 130
Distance: 71.4 km

Ironically, I came home via "that gate". It was definitely open when I rode through.

One last thing - I have chatted to my prosthetics specialist George and we will hook up again in the new year to start looking at the design and construction of a leg dedicated to cycling. Picking the right time for that is tricky, as since I am now trimming down, that affects the fit of my stump in the socket. So getting the leg too early might reduce its useful life.

I did however use some of the funds raised to purchase a new leg liner (or as Paul Craft calls it, the big blue condom that goes over my leg) and distal cup (the current cup is looking a bit worse for wear). That was $1300, so the benefit funds are already being put to good effect. I'll now be able to rotate the liners and hopefully get a bit more useful life out of them. Early in the New Year, I'll probably add a third liner to the stable.

So there you have the latest. All going well as far as training goes. More hard work ahead of me though, and probably a few races over the next month.

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Testing Times #2

In November 2006 in this post I wrote about one method used for testing my current level of aerobic fitness - the time trial power test. It is a test to see how hard you can ride for a given distance. As a test for fitness, it's not the time taken for the course that matters so much as the average power you can sustain during the effort.

Time taken to complete the course isn't a great indicator of changes in fitness, since time can be readily affected by conditions on the day (wind conditions as an example). But power is power, provided you are conducting the test in a reasonably similar environment (altitude, terrain and it's not hideously hot or cold). It also helps to make sure you are not overly fatigued on the day of the test.

The length of the test is typically 10-miles or 16-kilometres. Doesn't need to be exact as it's power we are interested in, not the precise distance or time taken. Of course, if you ride 10-mile TTs regularly, then they are perfect opportunities to use as tests.

Today I was scheduled to do my first such test since returning to the bike.

So what happened?

Well of course today it decided to be a stormy rainy yukky sorta day, didn't it. And right now I don't need the hassle or riding in the rain.

So that left me with the other alternative - to get on the ergo bike and go for it. So that's what I did. Only trick is I have no speed/distance data on the indoor ergo bike, so I opted for a 25-minute long test.

Unsure of how hard to start with, I decided on starting at 220+ watts and then to go by feel from there. Here is the power chart from my effort (yellow = power, green = cadence):


Overall, for the 25 minutes I had an average power of 248 watts and a peak 20-minute average power of 252 watts.

So that's not too bad all things considered.

Testing continues later in week, with a Maximal Aerobic Power test.

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Two by Twenty - Take 2

Way back I posted about a workout known as the 2 x 20. It's pretty simple. Ride for 20-minutes at around your time trial pace/effort/power, have a short break and then do it again. Combined with a warm up and cool down, it makes for a nice tight one-hour workout that's exceptionally effective at developing one's aerobic engine.

On a power meter chart - it looks a bit like this:


The squiggly yellow line denotes power output and was around 200 watts for two efforts lasting around 20-minutes. The horizontal dashed line shows 200 watts.

In between efforts I stopped and hopped off the ergo bike to remove my leg and dry the liner and leg, and replace so I could go again. It's a challenge I face at the moment as the leg liner tends to fill with perspiration making it a little weird to pedal. Imagine pedalling in loose gumboots with water in the bottom of them.

Of course there is nothing magical about 20-minutes. Overall it's about getting enough time at these levels. Some do 3 x 20-min. Others 3 x 15-min. Some ride the hour straight at that power. Typically though we break up efforts into smaller duration "chunks" (known as intervals) so that we can maintain perhaps slightly higher power than we may otherwise have the motivation to do all in one go.

So what's actually happening when I train at this level? Well lots of good things. The main physiological changes that are brought about by riding at these intensities include:

- increasing my muscle glycogen storage capacity. Glycogen, along with free fatty acids are key sources of chemical energy which is converted by our muscles into mechanical energy (and heat). Basically this means I develop the ability to ride hard for longer.

- increasing muscle mitochondral enzymes - these are the "mini power plants" inside our muscles, which use the available oxygen for the conversion of chemical energy to mechanical energy (as well as heat). The greater the number and density of these suckers we have the better

- increased lactate threshold - which is another way of saying one can go harder for longer. Blood lactate concentration is one way of determining how effectively our working muscles are performing at various intensities.

Now you gain these benefits by riding at lower intensity levels as well but the rate at which improvements occur is greatest at these intensities, which is an effort level equivalent to how hard you could maximally sustain riding for about an hour.

They are also effective at increasing my blood plasma volume, increasing my heart stroke volume (amount of blood moved per beat) and maximal cardiac output (maximum amount of blood I can pump per unit time) and for increasing the amount of oxygen I am capable of both delivering to my working muscles and actually utilising (my VO2 Max).

There are other funky things too, like increasing the density of blood carrying capilliaries inside the muscles - which enables a greater and faster transfer of oxygen to the working cells. On top of that, our (slow twitch) muscles fibres also grow.

The body is an amazing thing. It knows how to adapt when it is provided with a training stimulus. The trick is to keep providing that stimulus in the right doses.

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Thunderbirds Are Go!

Meet Thunderbird 7:

T7 resides in the spare room, specially cleared out for the purpose.

This new "space age" home built trainer is now set up for some serious workouts. Note the cat killer of a flywheel. Fortunately I don't own a cat. There is a safety cover, it's just not on there yet.

T7 also has inbuilt position adjustability in any direction you like. So I can use it for testing other cat lovers. T7 originated in the minds of some residents of "The Shire", so you can be assured it has some magic about it.



The flywheel gives a very realistic ride. I did my first short workout on it tonight and it felt great. I was able to tap out a much higher cadence and power than on the turbo trainer. A 30-min workout with an average of 169 watts.

The fan blades replicate wind resistance and give a nice cooling breeze as well.

The crank system is an SRM power meter. My buddy Pete helped install it for me. Well actually he installed it and I watched (my definition of helping can sometimes be a bit liberal), although it's not that difficult. But installing an SRM properly requires the right tools and a calibration kit, which Pete has and I don't (well not all the tools - a good torque wrench being the main missing component).

Also note the short crank on the other side. Over time I expect to be able to lengthen the cranks I can use until I'm back to a normal length crank. Next week I get my special bike leg attachment fitted.

The SRM crank then drives a Nexus hub, with an internal 7-speed gearbox (normally built into a rear wheel for commute style bikes). The Nexus hub then runs a chain to the flywheel. This "double reduction" gearing enables the flywheel to turn at very high speeds (in the order of 600 rpm), meaning the fan blades do their job by providing increasing wind resistance with an increase in speed and the rotational intertia of the flywheel replicates the inertia of a rider rolling along at speed.

Here is the T7 flight cockpit:



Ready when you are Virgil....

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Da PMC is da goods

What the? Nevermind. ;)

My re-introduction to training continues, this time with a 30-minute effort on the bike trainer this morning. So, I have ridden on the trainer six out of the last eight days.

This is shown in the chart below, which assigns a "training stress" score to each day's training as shown by the light blue columns.



The number shown bottom right is my "Chronic Training Load" an indication of how much training I've been doing over the last several months.

Not surprisingly, a CTL of 4.2 TSS/day tells me I've not done much training! Consider that my peak CTL for the last season I raced was 100 TSS/day and I have a long way to go!

But the good bit is I've been able to increase what I do on the trainer through the week, and the half-hour effort this morning is starting to get into the realms of useful aerobic training. I was watching some TdF highlights while riding. 2006 when Floyd Landis cracked on the climb to La Croix de Fer. I wasn't on the bike long enough to see it finish but Rasmussen wa on a solo break away, with Levi Leipheimer pursuing.


Speaking of Rasmussen, check out this You Tube clip of a commercial featuring Rasmussen. It's pretty funny. But you gotta understand why. It's not in English (well not much) but anyone who follows cycling will get it.

Here is the pic of the power meter file for this morning's ride. 144 watts total and a 20-min max of 156 watts. I reckon that's a pretty encouraging start to my training.



Bring on that new cycle leg attachment and look out!

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Just a little bit more

Well that chart above just about says it all. A 20-min effort on the trainer today and a little harder than on Saturday. Last 5-min at 158 watts.

It will be really interesting to see what difference being able to click into a pedal will be like with the prosthetic. At the moment just plonking my prosthetic foot/shoe on top of the flat bed pedal, while OK on a trainer, doesn't do much for power. I have been placing my "heel" on the pedal to simulate the position the pedal attachment will take.

And I have a suspicion I might be able to try a longer crank than the 100mm shorty I have on there at the moment.

First time in 15 months I've got the HR moving!

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15-minutes of fame

Not much to say other than since I have a new leg, I thought it about time I tried to turn a crank over on the bike (on the home trainer).

Here is the file from my 15-min effort.


A combination of very low fitness, new leg, pedalling a 100mm crank with a flat bed pedal on the left and my normal 175mm crank on the right. Combined with the PT's aliasing "feature" it makes for a funny saw-tooth power line.

Anyway, who cares what the line looks like, it was a ride right? :)

I was pretty sore before starting as the day before I had been on my feet a lot and actually managed to climb a couple of flights of stairs with full leg steps and no hands to guide me. That's something I haven't done for over 14 months... I think the ride loosened me up a bit but here's hoping I can start to get those exercise endorphins flowing before long.

Still working on the bike leg attachment.

Having done this 15-minutes though, I have the feeling a dedicated bike riding socket will be in order as I suspect some subtle (maybe not subtle) changes will be needed to the socket design. Time will tell.

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Sock it to 'em

The socks I use in side my current prosthetic leg. Lots.
Thick cotton ply jobs (3-4 ply) about 12" (30cm) long.

So what's been happening lately?

Well the trainer project has moved along a bit. The frame is under construction and the flywheel will be machined down to size/weight. I calculated we needed to reduce the radius of the wheel by 45mm to get the weight down to an ideal mass. The SRM power meter is on its way and I should have that in a few days.

I also had a bit of fun with John playing with those uber strong rare earth magnets, rigging up a crude device to enable us to test the theory that they'll provide some form of controllable braking resistance for the ergo. It was a good enough test for us to consider the next step. I fashioned up a rough design as to how we could make it work (keeping in mind the functional but easy and cheap to rig up theme):An online discussion of the project can be found here.

As for my leg - well Schooner is now a 7 to 8 sock kind of guy (meaning I have around 30 ply of sock padding out the leg so it will fit snugly into Schooner's hard outer casing) and as a result he ain't all that comfy anymore. I used to use just one. See the picture above for an idea of how much sock that is. These are fatter than thick footy socks - more like Grandma's knitted bedsocks!

Accordingly, and following a review by my rehab Doctor at the amputee clinic, a script has been written to get funding for a new leg approved (via NSW Dept Health). Once that is cleared (about two weeks), then George at the Appliance and Limb Centre will give me a call to come in for a new sizing. Leg will then take another two weeks to make. So I'm about four weeks away from a new leg. That's about two months faster than normal I'm told.

I won't go for the bog standard (Schooner-like) leg that the subsidy covers but rather use the subsidy to go towards a better model of leg, which will also enable a cycling leg attachment. It'll cost more but it'll be worth it.

My knee flex hasn't improved much despite the best efforts of my physio. Not her fault, I simply haven't done enough regular work on it. For the first time in a long time I have not had the same motivation to do the work needed. It's part mental and part due to my current leg not being all that comfortable. When you start the day with a sore leg, there isn't much motivation to train on it. So I'm hoping the new leg will help me along with that. Everyone says "don't be so hard on yourself". But it's being hard on yourself that gets results, so I'm a bit frustrated with myself at the moment.

My cycle coaching is going along nicely and keeping me mentally active, with another coach asking me to coach them (I have several coaches as clients). Quite ironic in some ways but I suppose coaches really appreciate the value of coaching. My understanding of the ways of training with power has a bit to do with it as well ;)

Apart from my cycle coaching activities (I really enjoy my coaching work), the time has come to gradually venture back to the office and begin the process of re-establishing my "day job". So this week, after various consultations with my Doctor and the HR people at the office, I ventured in for some meetings with the leadership of the business, mainly to say hello and also to discuss what I'll be doing when I start back there next week. It's 11 months since my accident, so there's quite a bit to catch up on. I won't resume my previous duties but instead I'll move into a business improvement role and report directly to the CEO. The challenge of getting back to the work routine will take some adjustment but it'll be good for me. I'll start part-time and will ramp up the hours as I am able.

This getting up early and shaving is a bit rich though!! :)

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