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8 mile TT - advice on wheels(11 posts)

8 mile TT - advice on wheelsChrisA
Jun 24, 2002 7:38 AM
All things being equal, what is the time or speed advantage of aero-wheels (full disc in the back, bladed or deep dish in the front) versus Mavic Ksyriums in an 8 mile ITT?
re: 8 mile TT - advice on wheelsWayne
Jun 24, 2002 7:47 AM
Go to analyticcyling.com and I think you can figure this out if you know:
1. the drag difference between the wheels
2. weight difference between the wheels
3. elevation change on the course
But my understanding is a wheel like a ksyrium which essentially is a non-aero wheel but reasonably light will always loose out vs. full aero until your traveling under about 12-14mph (i.e. going uphill). So any flat course your better off going aero, if it has significant elevation gain than you have to factor in the weight difference, if it's a hilly circuit you're probably still better off aero since you'll be going fast every place but on the steep uphills.
need more info, technical or straight, hilly or flat? (nm)Pack Meat
Jun 24, 2002 7:47 AM
Assume a flat course.ChrisA
Jun 24, 2002 10:49 AM
I'm looking for an aproximate time advantage of aero wheels over Kysriums. The Mavics are all I have for this TT and I want to know how much time I'm giving up to the competition. Assume I can go 25 mph with the Mavics.
Well since you we're too lazy...Wayne
Jun 24, 2002 11:10 AM
to do it yourself and I'm bored, I went to Analytic cycling and did it for you. I assumed the ksyriums had slightly less drag than a typical box rim and used a tri-spoke/disc as the optimal comparison. Assuming a 400 watt output over 8 miles you loose a whopping, are you ready for this, 5 seconds! Even in the worse case scenario of box rims and going slower (avg. 350 watts) the difference is only around 8 seconds.
Ksyriums or Rolf Vector Comps for mostly flat TT??ChrisA
Jun 24, 2002 11:10 AM
Assuming I can't my hands on some TT wheels, I could steal my wife's Rolf Vector Comps which have bladed spokes and a deeper rim. They're heavier by seem to be more aero. Any thoughts?
See my above analysis...Wayne
Jun 24, 2002 11:13 AM
if taking the extreme limits is only good for about 8 seconds than the differnce between these two is probably about a second or two in favor of the more aero wheels.
link for lots of aero infoDougSloan
Jun 24, 2002 12:36 PM
http://www.sheldonbrown.com/rinard/aero/

Check the Hed wheels site closely for info; the link is messed up, but you can get there by backspacing to the root url

also, this is good: http://www.bicyclesports.com/technical/aerodynamics/watts_drag.html

Doug
Aero vs. WeightCheaves
Jun 26, 2002 8:12 AM
Chris, in a time trial, unless it is SERVERELY hilly, always go for the more aero wheel, in your case that would be the Rolfs. You want a low spoke count and a deep rim. Also, look down at the wheel vertically. On a good tt wheel you should see nothing but the tire and hub. Eight seconds is a lot in a time trial. This past weekend, the four finishers ahead of me were all less than 2 seconds away. If I had gone a whopping eight seconds faster, I would have won.
re: 8 mile TT - advice on wheelsAlanE
Jun 26, 2002 8:31 AM
For what it's worth, I recently bought a CH Aero disc wheel cover and took 30 seconds off my best time in our weekly club time trial (6 mile loop, a few small hills). My regular rear wheel is a Mavic Cosmos 28 spokes. For $60, a lot of bang for the buck.
Buying for just one event makes you a bike geek!!!Canidraftyou
Jun 27, 2002 5:48 AM
Buying for just one event makes you a bike geek!!! I know that pisses some off in here. Use what you got! If you have a semi-aero wheel then use it. If not, dont go and buy a set of wheels because others are. Dont fall into the marketing crap! Sure Aero is better on flat TT or flat road racing. What region do you live in and is flat out of the question for most races in your region. Not even a debate on weight vs Aero. Aero wins everytime.

Peace