9 speed cassette, spacing question

[mtb_frk]

So I have two wheelsets, ksyriums sl, on one I have a ultegra cassette, and the other I have a dura ace, both are 9 speed. I have a 2mm spacer on each of them that is installed up against the hub body. When I swap the wheelsets I have to adjust my front and rear der., in the front the chain rubs on the inside plate of the der. and the rear it doesnt shift smoothly.
Anyone have any thoughts on why? I have other wheelsets that I swap in and out and havent had this problem, just with this one wheelset.

[AndrewS]

No idea, but a suggestion:

Swap the cassettes between the wheels and keep track of which needs what adjustment. That will either show you where the problem lies, or actually fix it.

Why do you switch between identical wheelsets? Cross tires?

[mtb_frk]

Yeah they are on my cross bike good guess.
Good idea. I am pretty sure the one that needs adjusting was on a different wheelset last year with no problems. I don't remember for sure because I turned that set into ss wheels back in the summer sometime.

[Ken Robb]

I don't know what normal production tolerance standards are for these products but they call all fall within spec and still require some fine tuning when swapped. There is a chance that swapping the cassettes to the other wheels might bring about a better match of tolerances i.e. you may now have a cassette that is near the upper limit matched with a wheel that is also toward the big end of the acceptable range. If your other cassette is near the lower limit swapping it with Mr. Big may get both sets into a Big meets Small marriage and everyone is happy. That's how I used to fiddle a bunch of Army Colt 1911A1 auto pistols to get some pretty good accuracy from most of them. Some were so loose there was nothing I could do to get them to shoot tight groups but THOSE suckers NEVER jammed even with sandy ammo. :beer:

[palincss]

There's only so tight a group has to be with the .45ACP to be "good enough to do the job."

[dave thompson]

There's only so tight a group has to be with the .45ACP to be "good enough to do the job."
...center of mass.....

[AndrewS]

That's what I was thinking, Ken, but I thought I'd leave off explanations about tolerance stacking.


It sounds like you guys are having a Firingline.com reunion.

[eddief]

if the cassettes both had the same range of cogs. Seems to me a bigger big cog could have an slight effect on chainline as it relates to front d and would of course have an effect on the rear d tension...that could require slight adjusting.

[AndrewS]

if the cassettes both had the same range of cogs. Seems to me a bigger big cog could have an slight effect on chainline as it relates to front d and would of course have an effect on the rear d tension...that could require slight adjusting.
No, different cog sizes should effect neither - especially not shift cable tension.

I suppose bad chainline might become more obvious with different cog combinations, but it would already have to be bad. And chainline, in the age of hollow BBs and freehubs, is almost never wrong.

[Ken Robb]

That's what I was thinking, Ken, but I thought I'd leave off explanations about tolerance stacking.


It sounds like you guys are having a Firingline.com reunion.

Steve Palincsar and I were in Ordnance Officer Candidate School for the Army at Aberdeen Proving Grounds at the same time (different companies) in 1967 so he "gets it". Thompson learned it all from his Marine son. :)

[oliver1850]

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