In article
<[email hidden]>,
David said:Quoted message said:On raod bikes, aerodynamics are more important than weight anytime you exceed about 20 km/h.
Most cyclists can do this, but then, most cyclists get no gains from having a more aero wheelset
(or a lighter one).
While I would agree that aerodynamics play a part in speed, that part is actually less significant
to justify the cost of some of the boutique style wheelsets.
Well, speed costs money. I'm not claiming a value proposition here. If I was, we'd all be riding
around on bikes found in dumpsters or at garage sales (er...) because a $10 garage-sale Bianchi (not
a hypothetical example!) is far more bicycle/dollar than virtually anything else (except a free
dumpstered Nishiki).
Virtually no amateur racer could make a financial case for expensive aero wheels, but then, precious
few fishermen can make a case for nice carbon fibre rods. The aesthetics and sensations of owning
and using this gear are enough to justify the purchase. Or, like me, the amateur racer puts a much
larger personal value on finishing position than the prize money.
Quoted message said:Quoted message said:If you are racing, it will depend on your discipline and style whether you should go for aero
wheels or light wheels (light, aero wheels are great, but are either fragile, expensive, or
both). That said, most riders should go aero unless they do a lot of hillclimbs.
Aero wheels are sometimes heavier than the regular boxed rims of the same lacing, spokes and hub
combinations. Most semi-aero rims like the Mavic CXP-33 or the Campy Mexico do squat in providing
any aero advantage other than it looks good. They may offer some aero advantage over regular boxed
rims, but the advantage could well be measured psychologically rather than factually for most
average riders. The only instance that I can think these aero wheels will benefit most is when you
have two same professional racers of almost equal might and their victories can only be measured
not in hours or minutes. They are measured in seconds and every saving seconds the aero wheels can
provide are beneficial to the racer that rides them. Otherwise, don't believe what most ads say
about these aero boutique wheelsets allowing you to perform miracles like Lance Armstrong.
You have to know what you're buying, but there are numerous places where you can go to see wind-
tunnel test results on these wheels. Assuming the rider is smart enough to buy wheels with an actual
aerodynamic advantage, the weight penalty matters very little in actual racing, but an aerodynamic
advantage can be massive if the rider exploits it.
Even in sprint situations, if you're going even reasonably fast, you're likely to gain more from the
reduced aero resistance as you sprint than you would lose in acceleration from the slightly lighter
wheels. The differences are small, but races are won by small differences.
In well-attended time trials, there can be no doubt: over a 40k time trial, a good set of wheels can
make a difference of 1-2 minutes. Ironically, because they spend more time on the course, slower
riders save _more_ minutes than faster riders over the same course when given the same aero
advantage.
That said, optimal body positioning can save you even more time than aero wheels, but both combined
is best of all.
escapevelocity.bc.cattresults.htmlOpen ↗
That's the results of the BC Provincial TT championships, a 37 km TT. I picked this at random
because I knew where the results were.
There were 64 finishers, and I cannot see any two consecutive riders who were separated by more than
a minute in the results, except for the 64th place rider, who was 97s down on 63rd. Less than two
minutes covered the top five, including a dead tie for 4th place.
This seems very consistent with a well-contested TT (for a thinly contested TT, look at the women's
results where four minutes separated first from second. But then, 2s separated second from
third...). In such a case, any rider who does not take the time to optimize their position and use
maximally aero gear is going to give away several minutes and dozens of places.
If there's a hypothetical rider in this listing (say, some XC mountain biker thinking about coming
over to the dark side) with top-10 power but box-section wheels and a mediocre bike position, we
would expect his aero drag problems to move him from 10th to about 47th place. That's using a
relatively conservative (according to the previous page cited) estimate of 6 minutes lost (roughly 5
to poor position, and another 1 for the wheels). The wheels alone would knock him down 7 positions
in the rankings.
Aero matters,
--
Ryan Cousineau, [email hidden] sfu.ca~rcousineOpen ↗ President, Fabrizio Mazzoleni Fan Club
