At the risk of sending a "me too" post...
I have to agree with John. If you want to convince yourself of the significance of QR compression, try the following experiment next time you are adjusting your hubs (or right now if you have too much free time). Adjust the hub so that the axle turns smoothly and there is not perceptible end play. Stick the wheel (tire removed) in the bike, adjust the QR normally, and clamp it down. Give the wheel a gentle push and observe the motion when it comes to rest. It will probably stop with the heavy part of the rim (the joint) at no particular orientation. It will just stop. Take out the wheel and loosen the hub a bit, so you can feel just a trace of play. The wheel probably still slows down and stops in a random position. As you back off on the adjustment a bit more, the rim will start to come to rest with the joint at the bottom, oscillating back and forth before finally coming to rest. That's about right. There is probably still not any play at the rim. Back the adjustment off again and again until you can just begin to feel play at the rim. Now pop the wheel off one last time and check out how incredibly loose the bearing feels. Yet in the frame, it is just barely loose. I'm not suggesting that you leave it like this, tighten it back up a tad. It is interesting though to see how much play the QR will take up. Note: in the name of science you should be sure to readjust the QR as necessary during the experiment to keep the load consistent (it will tend to tighten as you back off on the cones). I don't know if QR compression works by compressing the axle (as a column) or by forcing the cones against the threads, but it has a big effect.
Just a note: I'm not suggesting that this method of precisely adjusting your hubs has any bearing on performance, or is a worthwhile effort other than as a half-interesting experiment. The amount of energy taken up by a hub bearing, even when a bit misadjusted, is trivial relative to the aerodynamic loads of cycling at even moderate speed.
Tom "sounding too much like the geek that I am" Dalton
> Over the last forty years of working on bicycles I
> have been asked the
> question many, many times. So what is the answer?
> Campy for years has
> always sent their hubs a little loose allowing for
> compression of the quick
> release to bring the hub into perfect adjustment.
> There is also compression
> a factor occurs with less expensive hubs, but the
> manufactures tend to send
> the hub out adjusted with a preload or maybe you
> call it poorly adjusted.
>
> It has always been my experience that most hubs cone
> adjustment should be
> just a little loose to allow for the compressing of
> the locknuts and cones
> for a better adjustment. Some of you may not agree,
> but this is how I have
> been doing it for years with great results. We
> always check the adjustment
> on new bicycle and historically the hubs are tight.
> We could certainly
> increase our repair business if we did not readjust
> to the standard that has
> worked for all these years. Once adjusted we always
> use the leverage of the
> wheel installed on the bicycle to validate the
> adjustment.
>
> John Alden
> Chico, CA
>
>
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