Originally Posted by
carpediemracing
Several questions, all pertaining to 500m TT:
1. The Analytic Cycling site - is it really far off in predicting performance or even performance changes. Changing weight by 10 kg seems to have a minor effect but changing peak power duration just by a second has a massive effect.
2. For Nationals (USA) I assume that the UCI jig is used to measure the bike. Related to that if I have a custom built frame (it'd be a Tsunami or similar welded aluminum), would it be legal to race? It's definitely not on the UCI list. If not then I'd need to source a custom frame from a build that is UCI approved?
3. Related to that - are 24" wheels legal, if used as a pair? I see that 550mm is the minimum tire height and 24" tubular/road wheels are about 560?mm. However I don't see any pictures or mentions of any competitor using a 24" wheel. Nor 650c for that matter. (Related to that it seems there are no 24" rear wheels out there, and very few 650c rear wheels).
4. Related to that, would there be a measurable benefit to using a 24" or even 650c wheel for the 500m? I figure it would accelerate a bit quicker, and it seems like the most important thing is to get up to speed quickly - it takes a long time to accelerate, so reducing that time would be beneficial. I figured if there was an advantage then someone would be selling them but I don't see any out there.
5. Another wheel related question - is a front disc (700c) a hinderance in the 500m? For indoors I imagine it's okay, but even a 24" disc (I had one a long time ago) is pretty wiggly in any kind of wind.
6. 'm having a hard time seeing if there's an advantage to either sprint bars or aero bars for the 500m. I'm not a super powerful rider compared to some others so I assume that the aero bars would help maintain speed, but I've watched a gazillion 500m clips and it seems to go either way. I know personally that I saw a big pick up in speed with aero bars but that was in a normal time trial, not a 35-40 second effort.
7. For saddles I'm using an ISM now, so I'd either be right on the BB line (sprint bars) or 5 cm back (aero bars). I think those are the rules, unless I'm missing something.
8. Final related to that, if I was using 700c wheels and aero bars I'd have to raise the base bar quite high to clear the front tire, but for a 650c or 24" wheel I could leave the base bar height at the same height as my drops. For sprint bars it seems that they can be below the top of the tire by a decent amount so I'm okay. Running a 650c or 24" wheel would eliminate that measurement concern.
1.) weight should have very, very little impact (almost nil) on a flat track. Peak power for another second however... likely means you are accelerating (standing start is where you'll hit peak power) considerably faster, which will have an impact.
2.) The last few years they have been pretty lax with the jig. That said... you should at the bare minimum contact them and get the head comm's opinion. Quite a few bikes without a uci sticker get used... but it can change on the whim of an official.
3.) To my knowledge, so long as front/back are the same size, you're good
4.) *rough guideline* it comes out a wash. People thought similarly in regards to aerodynamics... smaller leading edge *should* be more aero (vs a 700c wheel) but to compensate you have a longer head tube, again basically a wash.
5.) ride discs when you can. Indoors in a TT, that's always.
6.) when aerobars are legal, you should use them (assuming you have an optimized position, etc etc)
7.) you get to choose one exemption, no questions asked (they don't measure you on the bike, just the bike) - with aerobars it's either a.) at least -5cm saddle to bb and up to 80cm reach, or b.)at most 0cm saddle to bb and up to 75cm reach. There is an extra 5cm reach available to people over 6ft (I can't remember exactly how tall you have to be, again, check out the uci technical guide)
8.) run what you have... again assuming it checks out ok.