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When to use heavy aero wheels(12 posts)

When to use heavy aero wheelsbimini
Aug 25, 2003 10:40 AM
I just bought a used set of campy shamals on ebay. I have started racing this year and was wondering which races I should use these in. I also have a nice set of open pros and a set of reflex training wheels.

My wife would have killed me if I spent several hundred on HEDs or any other carbon aero wheel. So if figure the shamals would help, besides I am not a light weight anyway at 180# and 6'-0". Dropping a pound or 2 off the waistline is cheaper than dropping a pound or 2 on the wheels.

I know I will use them in TT and probably on road races. There are no mountains here in Iowa, just rollers and some long steep rollers.

I plan on running my first crit next week. I assume I would be better off with the open pros with all the acceleration out of the corners. What is the groups thoughts here. Are heavy aeros of any help? My thoughts are they my help catch back up if/when I get dropped. I have caught back up in road races before by getting my position way down and pedaling like H#ll on the down hill after being dropped on the uphill.

I also race frequently at a 1/2 miler paved oval series. (3-15 lap straight races, point races, slow man out, etc) I have done okay (a 2nd and a couple of 3rd). I ussally have no problem hanging on and have even led more than one successful break, but I am weak on the sprints (my best max was 35 on this flat track). I assume I should stick with the open pros on these races (or would the aeros help in making the breaks)

Your thoughts are appreciated.
re: When to use heavy aero wheelsasgelle
Aug 25, 2003 11:21 AM
Use the shamals in the crit and on the oval. The aero advantage will more than offset any weight penalty. This can be checked at www.analyticcycling.com Assume some fixed power, then calculate speed for the weight/drag of the two wheels.
I'd think notfiltersweep
Aug 25, 2003 12:34 PM
A crit is about acceleration which is about rotational mass... the Shamals are pigs. Use the OPs or whatever you have that is lighter. You need to deal with speed changes. You won't be catching much wind if you stay in the pack, and if you fall off the back, you are screwed anyway.

Use the Shamals for a TT, but that is about it.
Not a matter of opinionasgelle
Aug 25, 2003 1:19 PM
It's not a matter of opinion. You can run the numbers yourself at www.analyticcycling.com and see that acceleration effects are an order of magnitude less and rotational inertia is 2 orders lower than other factors. The reduction in drag from being in the pack is order 25% but even doubling that to 50% leaves a factor of five between acceleration and all others.

If you don't want to work it out yourself, Kraig Willett has an excellent article at

http://www.bike.com/template.asp?date=8%2F1%2F2001&lsectionnumber=6
Not a matter of opinionfiltersweep
Aug 25, 2003 2:37 PM
Interesting- I ran the crit corner model and the aero wheel setup came out ahead by 0.01 s or 0.18 m after 100 m following a corner.

I'm still not convinced I buy it all for pack riding... never mind the fact that it would be easy to build very heavy cheap aero wheels, yet the closest thing to them are Cosmic Carbones these days...
Not a matter of opinionBigFreddy
Aug 25, 2003 6:50 PM
asgelle is right, I've won more races on a set of Ventos than any other set I have. Crits are NOT about acceleration (unless you don't how to corner) they are about speed. Shamals are fast wheels.
Thanks Allbimini
Aug 26, 2003 4:57 AM
Seems I should flip a coin. I still think the shamals will help me (a heavy guy @180) on the Road races. I just can't hang on to the lighter guys up the long hills when they are surging. My only chance is to catch back up on the down side.

I am still not sure what to do about the crit this weekend. My goal is to hang with the lead group, not to win. I will not do any pulling since this race usally has a good turnout with a strong field. I am very smooth in the corners when alone but I have not raced a crit before. Chances are I will loose speed in the corners until I get comfortable with the pack dynamics in the crit (Cat4,5). The OPs are a wheels set I have used a lot and am comfortable with and can corner fast on when I am out farting around. I will probably go with those. If I am too nervious the race could turn into a Time Trial for me so the Shamals my help then:)

The oval series is over for this year, but next year I will give the shamals a try there. With 5 races in an evening I can always switch wheels if I am not happy. Since I am not the strongest sprinter I my try breaking more. On the points races I have seen guys carry their speed after the first sprint and put a 1/4 to 1/2 lap on the field and carry that trough to the end of the race.
Thanks AllMShaw
Aug 26, 2003 9:48 AM
Try this: put the Shamal on the front, and the Open Pro on the back. That way you aren't trying to accelerate both heavy rims.

Since it is more important to have aero in the front, it may be the best of both worlds.

Mike
Thanks Allasgelle
Aug 26, 2003 11:00 AM
Yes it's true that the aero benefit is greater for the front wheel than the rear (and obviously the weight penalty is the same front or back), but even in the rear, the aero benefit overcomes the weight penalty ( www.analyticcycling.com, www.bike.com/template.asp?date=8%2F1%2F2001&lsectionnumber=6 )
so the question still is why would one not use aero wheels if possible. Again, remember that accleration effects are 1/10 aero drag + rolling resistance + other losses.
There's another factor you guys seem to have forgotten.shirt
Aug 26, 2003 3:41 PM
Stiffness.

I don't know anything about the relative stiffness of the Shamals, but I know that a well-built set of standard tubular crit wheels can be very stiff. My barely-aero wheels are two year-old Xaeros, and they're about as stiff as a waterlogged pretzel. They're actually disconcerting in a sprint, and I'm never comfortable pedaling my heart out into them in the final 150m. I don't know how much power I'm actually losing in those wheels, but whatever it is, that combined with the poor "feel," is a limiter.

I know you can make the argument that if I arrive into the sprint fresher because of aero wheels, it will matter less. However, I think if you're hiding in the bunch the way you're supposed to, the aero wheel won't be enough to offset the comfort and ability I feel my super-stiff tubies give me.

/shirt

ps: Yeah, I know the answer is to spend millions of dollars on super stiff, super aero, carbon this, carbon that wheels, but it's not an option for me (and probably many.)
Hiding in the packasgelle
Aug 26, 2003 4:36 PM
I think if you're hiding in the bunch the way you're supposed to, the aero wheel won't be enough to offset the comfort and ability I feel my super-stiff tubies give me.

see Willett's article at:
http://www.bike.com/template.asp?date=8%2F1%2F2001&lsectionnumber=6

He has power data from a rider sitting in in a 1-2 Crit as well as the analyticcycling.com model. It's surprising but the benefit from aero wheels is significant (1.3%) even for a rider sitting in.

ps: Yeah, I know the answer is to spend millions of dollars on super stiff, super aero, carbon this, carbon that wheels, but it's not an option for me (and probably many.)

I've never mentioned spending millions of dollars or carbon rims. In fact the question was which of the wheels the OP already owns would be better suited for him. But I would say that by focusing on getting the deepest profile rims possible and not worrying too much about weight, it's possible to build up a set of fast wheels from component parts for much less than the boutique wheels sold complete from the manufacturers.
My CosmicsMShaw
Aug 27, 2003 9:22 AM
Between the highly tensioned spokes and the deep rims, my Cosmics are about the stiffest thing I've ever ridden. Since Shamals are about the same style wheel, I can only assume that they ride similarly.

I've heard that the Xaeros are noodles. Good for triathletes, not so good for crits.

I've also had really good feelings from my Ritchey Pro wheels. Fairly aero, fairly light, not very expensive (crashes happen in crits, after all...)

Mike