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Low Weight VS Aerodynamics(15 posts)

Low Weight VS AerodynamicsVetteRacer
Feb 2, 2002 9:34 PM
I have a set of CXP30 Rims, 32 hole with Record hubs. They weigh 943/1193. Compare that to a set of custom laced normal rims (non aero) and alot can be saved.

But, is it worth it? I know wheels are a big place to loose weight (I could loose over 3# in my current rotation setup). But do the aero rims counter the effect?

This would be for normal road riding, not TT or Tri riding or anything.

I hope this question makes sense.

Thanks
Matt
re: Low Weight VS AerodynamicsMcAndrus
Feb 3, 2002 5:22 AM
Aero rims have the best effect in time trials where you are always in the wind. Are you riding in fast groups or races? If so, then the benefit of aero rims is reduced because you're working within a group and usually on someone else's wheel.

That's why I ride box section rims: a set of Protons and a set of custom wheels with Mavic OP rims. I like the lower weight where it helps me, accelerations and climbing.

http://www.analyticcycling.com has some interesting math on the aero rim vs regular rim question.
re: Low Weight VS Aerodynamicsmerckx56
Feb 3, 2002 8:15 AM
the cxp30s are bombproof and great for training. the heavier weight if the rim will make then accelerate more slowly, but they will hold speed better once you get over 20-22 mph. it's simple inertia. the outside "rolling" weight will be greater than an open pro. they will also be much stiffer, due to the fact that the spokes are shorter and the tension can be jacked up because of the internal eyelets. the cxp30 rim is identical to the rim that mavic uses for it's cosmics (elite, equipe, and expert, from years past). train on the cxp30s and get a pair of lighter wheels for crits or climbing, you'll feel the difference!
re: Low Weight VS AerodynamicsWoof the dog
Feb 3, 2002 10:18 AM
you sure its inertia? they will hold a better speed (at higher speed) due to their more aerodynamic profile, not due to their heavier rim, i think. Someone explain this one to me, cause I am not sure!

thanx a bunch

woofie.
flywheel effectKEN2
Feb 3, 2002 10:30 AM
The greater weight of the aero rim means it stores more kinetic energy. This in turn will make it slower to accelerate and to decelerate. But once you get it up to a given speed, if you coast on the level or down it will slow down at a slower rate than its lighter counterpart (say an Open Pro) because of weight alone; and it will slow down less than the Open Pro because it's more aerodynamic as well. Problems come with a lot of jumps of speed or hills...
oh ok nmWoof the dog
Feb 3, 2002 10:43 AM
re: Low Weight VS AerodynamicsKerry Irons
Feb 3, 2002 5:29 PM
A very good set of aero wheels would save you 0.3 mph at 20 mph, which translates to about 4 minutes saved over 100 miles. Very significant if you're racing TTs, not too significant if you're not or race in a group. Aero rims are heavier and tend to be more cross wind sensitive, and build stronger wheels or require fewer spokes. Your choice.
re: Low Weight VS Aerodynamicsweiwentg
Feb 3, 2002 6:23 PM
what of semi-aero profile rims like the Velocity Aerohead? how much advantage (if any) does that translate into?
re: Low Weight VS AerodynamicsWoof the dog
Feb 3, 2002 8:30 PM
from what i have heard and read on this and other forums, there are almost no benefits to having aerohead vs, open pro or other non-aerodynamic rims. They say you need a 50mm+ rim to make a significant difference. I also agree with what Doug said below there.

Sincerely

Woof.
practical adviceDog
Feb 3, 2002 6:38 PM
Go to http://www.analyticcycling.com and run some numbers.

There is no one right answer, because different wheels will be better for different conditions. Most sources say that over all, you are faster with aero wheels, rather than lighter. Of course, the slower you ride, the less this will be so.

Ideally, get light and aero. Then there is no compromise. Zipp 404 or 303 are good examples.

If someone tells me that such-and-such wheels will save me x mph, I'm skeptical. For one, does it take into account all the terrain types I'm riding, alone or drafting, my power, weight, etc.

Here is some practical advice, though. If you are riding with others, if you are going to get dropped, chances are it's going to be up a hill. There, lighter is better. On the flats, you can suck wheel. If you are getting dropped on the flats, it ain't the wheels. If you are riding alone, it doesn't matter much at all, unless it's for time. If it's for time, go aero.

Doug
crosswindsgtx
Feb 3, 2002 8:44 PM
In my experience, most of these aero rims suck in crosswinds--not fun, especially if you a lighter rider. This may or may not be an issue, depending on where you ride. I think unless you are doing time trials, the disadvantages outweigh the benefits.
truedatWoof the dog
Feb 3, 2002 8:53 PM
true that. I rode my cxp 23's for a year+, when in a group the wind would hit me, I would be all over the road leaning into it vs. everyone else just laughing at me. Dave's speeddreams built with sun venus rims had an even worse effect even though they are not much taller than them stupid cxp23. I can't even imagine riding Zipps, i would be blown off the road in a second. You think eating more doughnuts would do the trick?

Sincerely

Woof, the dog that likes doughnuts(not dognuts!)
yeah, donuts would helpgtx
Feb 3, 2002 10:14 PM
you'd probably hold a better line in crosswinds but then you wouldn't be able to climb. Tradeoffs... ;)
truedatVetteRacer
Feb 3, 2002 11:11 PM
WOW!
Now you got my scared. Mavic CXP30 rims, on a Y-Foil. Hope I dont fly away.

HAHA
Oh well, I will see, can always build another bike (trad frame) sometime.
Thanks for the replys all!

Matt
crosswinds - get 303'sDog
Feb 4, 2002 6:32 AM
if cross winds are a problem, then get the 303's. They don't seem to be too bad, except in the worst winds.

Doug