Jan 7, 2003 3:02 PM
|I've noticed that a lot of wheel manufacturers (Hed, Zipp, Bontrager, Mavic, etc.) create aero wheels by reducing the exposed spoke length on the wheel by using deep section carbon fiber rims. These wheels are usually very expensive. Why don't manufacturers simply reduce the spoke lengh by using a light, cheap, replacable plastic fairing around the diameter of a regular rim (like an Open Pro). Wouldn't the wheel be light, cheap and aero? The only such example that would be close is a Mavic Cosmic Carbone. Here, an aluminum rim is used with a plastic fairing, but these wheels are still $1000. They also apparently have carbon somewhere? Does anyone have an answer to these questions?|
|I suspect those are a handful when big trucks pass ...||Humma Hah|
Jan 7, 2003 3:24 PM
|I have not tried a bike with faired wheels, but they look like they would be scary when big trucks or strong sidewinds load the wheel. This would not be so much of a problem on a closed course or track.
As for the rest, one of the most satisfying things that I ever experience on a bike is to pass a bike equipped with, say, a set of Spinergy carbon aero wheels on my cruiser. I believe there are an awful lot of those sold to folks with more money than speed, who think high-zoot toys are a substitute for fitness.
I recently picked up a used Spinergy front wheel at a bicycle flea market to use in a non-cycling project at work. I paid $50 for it, and that seemed about the going rate that day. Most serious riders seem to still prefer honest spokes, are not quite sure they trust carbon, and especially not used carbon wheels when they're not quite sure why they're being retired by the seller.
|because it is too smart?||cyclopathic|
Jan 7, 2003 3:37 PM
|or maybe because Mavic had patented it first?
btw Cosmic Elites have plastic fairing and they are in 300-400$ range. They are not as aero still way better then regular wheels.
|re: Aero Wheels||Woof the dog|
Jan 7, 2003 3:43 PM
|well, the profile of the fairing at the inner edge would be pretty thick, and the deeper you make the fairing, the thicker you'd have to make the fairing. At some point it will have to be as thick as the rim. If you look at carbon rims, they try to make them relatively thin at the inner edge by the spokes. Carbon fiber is probably the lightest material to make the fairing out of. Plastic may not weigh a whole lot if it is the cup you are holding in your hand, but speaking from a personal experience, the weight of the material adds up very quickly once you make the whole fairing out of it that has a lot of surface area. You are probably looking at 200 grams per wheel increase in weight. You could make it very thin, but then it would be fragile and maybe it would even bend in the wind and stuff. You'd need some kind of way to attach that to the rim, and again that means an increase in weight. Also, do you take off the fairing to true the wheel/replace the spokes?
I would say that any relatively modern wheel is a really amazing thing, given how much support it can give with such a little amount of material. The fairing design is probably only for Mavic's use (patent stuff). There is a reason why wheels like that are not popular. It is probably aerodynamics and weight, or maybe stuff like marketing and design ownership rights.
woof the dog.
|re: Aero Wheels||Woof the dog|
Jan 7, 2003 3:49 PM
|what is the weight of the Cosmic carbone wheelset w/out skewers? What about the Elite version?
Need to go check the rna.
|re: Aero Wheels||upandcomer|
Jan 7, 2003 4:06 PM
|I'm not sure what you mean by
"the profile of the fairing at the inner edge would be pretty thick, and the deeper you make the fairing, the thicker you'd have to make the fairing. At some point it will have to be as thick as the rim"
The Cosmic Carbone's fairing are just tapered from the rim towards the center.
I guess my real question is why are these wheels so expensive, aren't they just thin cheap plastic attached to a regular rim? If so, it's a suprise that other wheel manufacturers don't produce similar wheels at lower prices.
|re: Aero Wheels||Woof the dog|
Jan 7, 2003 9:07 PM
|i think this is right. The fairing of the wheel is not as thin of the profile as the real carbon rim, So the deeper is the fairing, the thicker it has to be, or actually you could make the fairing thin, but then the spokes would have to come out of the sides through the holes like in shimano type of wheels.
Jan 7, 2003 10:18 PM
|re: spokes out of the sides||cyclopathic|
Jan 8, 2003 8:10 AM
|that's exectly what Cosmic Elites do. Granted it is only 30mm profile so it isn't big deal offset is only a couple MM and not even noticable, but even with 45mm it won't be as bad as you say.
One of the problems you'd run into you need to use extra long nipples to be able to true wheels.
BTW Cosmic Elites do not weight much over Carbones. Elites are 850/1095 and Carbones 885g/1090g. Carbone front is heavier despite 4 less spokes.
|re: spokes out of the sides||Woof the dog|
Jan 8, 2003 10:27 AM
|well, you could use the hex type of nipple to true it from the outside (take off rim tape and use a special tool, i guess). right?
Jan 8, 2003 11:33 AM
|wouldn't be very convenient though. The other way is to use straight pull spokes and reverse nipples to hub.
I think the major fight is to reduce number of spokes, not to make flaring bigger per say. Doing carbon as part of rim allows to make rim stronger and reduce spoke count.
|Economies of scale||Kerry|
Jan 7, 2003 4:40 PM
|Two factors causing high prices for aero wheels are the poor economies of scale and the marketing factor. Face it, there aren't that many of these wheels sold. Given the number of suppliers out there, you can think of most of them as being hand made, much more hand made than a typical bike wheel. That means costly. Add in the fact that people appear to be willing to pay a serious premium for the aero factor, and you get the formula for high prices. It's not easy to reduce the manufacturing cost, because there's so much labor (not material) cost. The funny thing is that unless you're earning your living with the wheels, the savings in time you'll get are not worth a nickle.|
|re: Aero Wheels||fractured|
Jan 7, 2003 7:21 PM
|Hmm where to start.... Ok first the Cosmic Carbone's fairings are carbon, hence the name carbone.
Second, I'm sure Mavic has patented their wheel
Third, UCI regulations forbid fairings in competition
Fourth, an Open Pro wheel isn't really light, and would gain a lot (more than a Mavic) with a fairing solid enough. Also, wheels used under competition must pass a shatter test. Compare to stock Zipp's at 1200g
Fifth, there are still far more aero wheels, no one in their right mind would claim Mavic to be the best. Spoke count and shape matters as much as the rim, so a standard 32 spoke faired wheel still wouldn't be that aero.
For it's intended purpose, weight isn't a big concern with the Mavics. Time trial bikes are built to be aero, not light.
Hummah, I don't think Spinergy's are looked upon very well at all anyway. Maybe the guy was just resting. A bit of money does not make you automatically fast, maybe he doesn't have time to put in enough miles or wants to play baseball with his son instead. Plus like you said, these wheels sell cheap now, maybe he got them because he liked how they looked.
Jan 8, 2003 6:49 AM
|"Third, UCI regulations forbid fairings in competition"
What are you saying here?
The Carbones have CF fairings but you see them in every major tour.
|re: Aero Wheels||mainframe|
Jan 8, 2003 2:27 PM
|"The funny thing is that unless you're earning your living with the wheels (or any component for that matter), the savings in time you'll get are not worth a nickle." Kerry hits it on the head!|| |