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Surprising difference in "feel" from wheel change(5 posts)

Surprising difference in "feel" from wheel changeJohnG
Jul 1, 2001 7:33 PM

I recently finished my MasterX build and had been using a set of CC built open pros on it. The bike was surprising stiff and dare I even say harsh.... :( I had rationalized that this ride quality 'snafu' was due to the "fact" that I was a bit light for the frame (MasterX is recommended for riders >165#) and that I had ultra light tires (Veloflex pave's) and the Star fork on the bike. This fork looks like a monster designed for Godzilla. ;)

Anyhooo..... I had built a set of velocity aerohead wheels (with Revo's) for another bike and out of curiosity I threw them on the Cnago. WOW...... what a difference!! With the same Pave tires (at the same pressure) the bike feels like a completely different animal. It's MUCH smoother and "quieter" .... in fact my right shift lever is no longer rattling like it did with the open pro's. Hmmmm..... I remember when I built these wheels that the aerohead II's were very squishy when doing a rim flex test. Also, I can't say the wheels feel unduly flexi, as I didn't notice any squirmy feeling when doing a short acceleration. I've got a steep hill I'll attach tomorrow but I'm hopeful that they won't sap me. ;)

OK, TIFN.... has anyone else had this kind of response from a wheel change??? Oh, the open pros have rather high spoke tension and when I built my wheels I didn't crank them up as much. I'm pretty confident the aerohead build is OK as I've got about 500 miles on the rear and it's held a great 'true' through some ugly urban riding. I've also got Brandt's book and read through much of his theory. I actually don't agree with some of his conclusions but heck... that's another story.

Comments from wheel experts would be appreciated.
Thanks JohnG
re: Surprising difference in "feel" from wheel changeJofa
Jul 2, 2001 9:07 AM
Spoke tension has no effect on wheel stiffness; spoke elongation is a function of its material characteristics. It's been shown experimentally repeatedly that the flexion of a rim in use is so little that it couldn't be 'felt' over the much greater distortion of a tyre.

Its all there in Brandt's book, with which you say you disagree... but the experiments and data regarding this are all there as well, so I don't quite see what there is to disagree with.

I'm quite convinced that any perceived difference in the ride quality of wheels or for that matter frames, as long as they are all of roughly equivalent design, is imagined: but this may be seen as a testomonial to our keenly imaginative natures, and that is only a good thing. If you prefer riding on your newer wheels then that is enough reason to ride them, in my opinion.
star fork with master?ColnagoFE
Jul 6, 2001 10:12 AM
did you spend the extra cash for the star? Usually the Force or the Flash fork come standard w/ it.
star fork with master?JohnG
Jul 6, 2001 1:36 PM
I got a VERY good price on the "upgrade". However, I'm wondering if the Star fork is more than I bargained for. It's built like the preverbial! The good part is that the bike is less than 18.5# which makes climbing fun.

I've done about 400 miles on the new wheels and there is a definate difference between them an my open pros. The good part is that I can increase my tire pressure back to 105 front 115 rear now without my teeth getting jarred loose.

Oh, my right brake lever no longer rattles.... but hey, wheels, or spokes, or tension don't make any difference right. ;)

to make slightly clearer...Jofa
Jul 7, 2001 7:35 AM
Various spokes of different cross-sections will stretch by different amounts under a given load. My point is that this variation is negligible, at most 100th that of tyre deflection.

A given spoke will lengthen by a consistent amount under a consistent load, regardless of the tension it is currently under; that is, a load which will cause a spoke to lengthen, say, 0.2mm from nearly slack, will also lengthen it 0.2mm when the spoke is highly tensioned. Therefore the spoke tension is irrelevant to overall wheel rigidity, as long as the tension isn't so low that unloaded spokes go slack.

This is all eminently testable, and the results are consistent and available. Sheldon Brown probably has the data on his site somewhere, as do Wheelsmith (I think), if you don't like Jobst's version.

I don't mean to upset anybody, but you did ask.