Straight Wheels

Triathlon Forum
1

How true should a wheel be? What is an acceptable tolerence? And how does a slighlty out of true wheel effect your speed over a 40 - 60k course?

Thanks

2

How true should a wheel be? What is an acceptable tolerence? And how does a slighlty out of true wheel effect your speed over a 40 - 60k course?

Thanks

That does interest me, too. My new HED H3 (rear wheel) seems very untrue. When I lift the bike and spin the wheel very fast I can feel that it rotates untrue. It is also noticeable when riding.

regards,
Frank

3

When I build new wheels I will generally get within .015" which is probably comes from the manufacturing process of the rim. A used wheel in my opinion should be within .040" (1mm) at the very worst for racing. You also have to look at how round the wheel is. Just because it may be straight side to side doesn’t mean it is round. You will have to take the tire off and measure high and low spots on the outside of the rim. If the outer edge of the rim is chipped up then you can set a dial indicator on the inside face of the rim. Also check the axle to see if there is any play in it.

For time trialing you don’t use brakes as much so you can get away a slightly out of true wheel. If there is a lot of cornering your braking may be uneven.

For a wheel that is hopping, I would first check for roundness, then check for balance (without a tire). Most of the wheels are slightly lighter on the side with the valve hole. If it is round and balanced, mount the tire and check again. It is possible that the tire and tube are unbalanced or my even have high and low spots.

My 2 cents

jaretj

90% of being smart is knowing what you’re dumb at

4

We touched on this on one of my disc/tri spoke posts earlier in the week. My Hed 3 front has a slight high spot of about 1mm but apparently this is common on wheels like this and I don’t find any problems with it (unless I’m out of the saddle and really honking it with my 190lb ass flexing the front fork).