tag:blogger.com,1999:blog-35788819.post1839802727414089897..comments2023-10-12T00:18:31.629+11:00Comments on Alex's Cycle Blog: Old SkoolAlex Simmonshttp://www.blogger.com/profile/00698332397074026424noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-35788819.post-70709929790928215152009-03-28T14:44:00.000+11:002009-03-28T14:44:00.000+11:00Well the concept of "optimal power" is discussed i...Well the concept of "optimal power" is discussed in detail in a paper I published last year. The process is a little too complex to explain in a blog comment.<BR/><BR/>If you sign onto Google groups wattage forum, you can view the discussion and see the paper here:<BR/>http://groups.google.com/group/wattage/browse_frm/thread/87ba9c8913f77ebb/<BR/><BR/><BR/>As for the comment on drivetrain losses, well apart from making sure all the components in the drivetrain are working effectively and are clean and properly lubed, then the only other item to consider is the size of the chainring used, as this does affect transmission efficiency.<BR/><BR/>Typical losses on a geared road/TT race bike are in the order of 2-3%, so 10W is quite a plausible loss.Alex Simmonshttps://www.blogger.com/profile/00698332397074026424noreply@blogger.comtag:blogger.com,1999:blog-35788819.post-67576812270020559902009-03-28T14:27:00.000+11:002009-03-28T14:27:00.000+11:00How did you calculate "optimal power"?How did you calculate "optimal power"?Smithhttps://www.blogger.com/profile/12542444891160456334noreply@blogger.comtag:blogger.com,1999:blog-35788819.post-69360951919069494142009-03-20T21:45:00.000+11:002009-03-20T21:45:00.000+11:00Well Buttsy - I'll be doing some TTs in the not to...Well Buttsy - I'll be doing some TTs in the not too distant future on a TT rig, so I'll have a reasonably good comparison to share.<BR/><BR/>A generous offer to loan me a TT bike (from a formaer client) will get me started until I can get my own rig sorted (which is a project underway).Alex Simmonshttps://www.blogger.com/profile/00698332397074026424noreply@blogger.comtag:blogger.com,1999:blog-35788819.post-87011350825399016082009-03-17T05:11:00.000+11:002009-03-17T05:11:00.000+11:00I would like to hear more about how to have an eff...I would like to hear more about how to have an efficient drivetrain and what is an excellent, good and fair drive train loss. I think I'm seeing about 10 watts of loss in my drivetrain and that's what I've heard others report.<BR/><BR/>In your article you said; "an efficient drivetrain so power is not "lost" between the cranks and the rear wheel."Harryhttps://www.blogger.com/profile/08708384358277359276noreply@blogger.comtag:blogger.com,1999:blog-35788819.post-40285679061535229622009-03-16T15:11:00.000+11:002009-03-16T15:11:00.000+11:00There are two methods I use:The regression method ...There are two methods I use:<BR/>The regression method and the Chung method. Chung method can be done fairly easily from simply riding a course with a known elevation profile and not much wind about.<BR/><BR/>See this post for details:<BR/>http://alex-cycle.blogspot.com/2008/03/funky-things-with-power-meter-77.html<BR/><BR/>No need for special software, it's just some home brew Excel spreadsheets which do the maths for you. I created a couple of versions for each of SRM and Powertap data files. They are located at the wattage forum on google groups.Alex Simmonshttps://www.blogger.com/profile/00698332397074026424noreply@blogger.comtag:blogger.com,1999:blog-35788819.post-12423437702971211522009-03-16T11:31:00.000+11:002009-03-16T11:31:00.000+11:00how do you go about calculating the CDA number out...how do you go about calculating the CDA number out of it. I don't want to know the math, because its way over my head, but given that you have power, elevation, wind, air pressure, etc, obviously it can be calculated. So did your number come from a proprietary software or what? I do a lot of TT's and would like to be able to get an average number on a given day. Thanks.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-35788819.post-61153639944045636742009-03-10T15:43:00.000+11:002009-03-10T15:43:00.000+11:00I would be interested in the difference a time tri...I would be interested in the difference a time trial bike makes as I have just bought one and really want to get better at time trialling....havent got your fancy power stuff, I have polar but dont use the power much. love looking at your graph...interesting and you certainly have some interesting reading about power etc. I did ITT on the weekend 30km and it was all about when to power upand when to conserve....Judithhttps://www.blogger.com/profile/16800437606008658030noreply@blogger.com