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The more aero wheel on back or front?...(6 posts)

The more aero wheel on back or front?...TFerguson
Dec 9, 2003 8:34 AM
Track bike. Say I have a 30mm deep rim and a 50mm deep rim. I would think that the 50 would do the most good on the front, but the reason I ask is that you only see disk wheels on the back. Is that just because any side wind is just too hard to handle with a disk on front?

Thanks,
TF
Front wheel provides steeringjw25
Dec 9, 2003 9:34 AM
so having a large sail up there would be dangerous. With an enclosed track, I suppose you could run a front disk, but they'll probably be heavier than a deep-section wheel, and might not ride as nicely. There may be rules as well - I could see the draft of a passing rider affecting the front wheel to some extent, and with riders so close together, a small wobble may put most of the race out.
On an outdoor track, no way. On the road, definitely not. Rear disks can be handled, as they push the frame from side to side, but up front, winds swing the fork. Heck, even 58mm Zipps are affected by winds, though not nearly as badly.
For your example, though, I'd run the 50mm up front. The rear wheel is seeing "dirty" air already, since it's passed the front wheel, fork, frame, and your churning legs, so an aero rear makes less difference than an aero front.
FRONT!MShaw
Dec 9, 2003 9:42 AM
The back wheel's already in some pretty nasty air...

Discs on the front are only a good idea when there's no wind. Makes for some interesting steering. Indoor velodromes are about the only place you're going to see front discs any more.

BTW I have the pair of wheels you're talking about. I have a pair of 404s that I race and a 340 rear that I train on. When I put the 340 rear wheel on, I can tell it isn't as fast as the 404 rear wheel. I can tell even more when I put on a regular front wheel for training, but you didn't ask that question.

I've owned a disc. I really like them, BUT they're harder to accelerate. Once you get them moving its more like linear resistance vs. the exponential resistance of a spoked wheel. Its hard to describe. I would like another disc. The one I want is the Accel 675g disc or the Araya disc that weighs about the same but costs 4X as much. Mmmmm, discs that weigh less than a regular wheel.... Mmmmmmm.

Mike
FRONT!swvegg
Dec 11, 2003 1:54 PM
I was under the impression that the Accel disc is 675g without the hub.
To answer the question - 50 on the frontbimini
Dec 9, 2003 10:35 AM
The air is cleaner and the longer airfoil will do more good in the clean air. At track speeds you need the deep section. In an indoor track situation a disk does not improve things much over a good deep section wheel. The numbers of a H3 wheel as compared to a disk are close to the same in a pure head wind.

The rear disk become an important factor in a cross wind. In a strong cross wind the disk starts to act like a sail and the sail effect can become greater that the drag meaning the wheel and wind is contributing energy not taking it away.

I lost an argument due to this in the racing section awhile back when the question was asked if you could afford one wheel which is better, a deep section front or disk back. I thought it was the front but someone else claimed a rear disk. When I looked at the numbers with a 15 degree and 30 degree relative airflow angle (rarely do you have pure head wind on the road)the rear disk won.

You are correct about handling issues of front disks in the wind. A disk has better numbers but that does not help if you crash and burn.
Thanks all. TFTFerguson
Dec 9, 2003 2:22 PM