My primary rear wheel works great on both of my road bikes. It has a 10 speed IRD 11-34 cassette. Bike A has a Deore XT RD paired to DA 7800 shifters. Bike B has a Rival Mid-cage RD.
The problem is when I try and use my backup wheel. It has a ten speed SRAM PG1050 11-32 cassette. It doesn't shift right on either bike. I suspect that the distance from the hub to the cassette is different on the two wheels. Can I use spacers to adjust that distance on the backup wheel (I don't want to touch the primary wheel or the RDs since they work perfect now)? Or is there some other way to adjust the distance? If I use spacers, is there some way to measure something to get the right distance or is it just a matter of trial and error to find the right spacer?
Cliff, First I'd swap cassettes and see if the back up cassette works without RD adjustment on the primary wheel. If it does I'd swap them back and measure from the chainstay to the 11T sprocket on both wheels to determine how thick the spacer needs to be. Are the rear hubs different brands?
RoboCheme: I would expect to need to make minor derailleur adjustments when swapping wheels even with the same make and model of hub and cassette, due to manufacturing tolerances. In addition the "B" screw will possibly need readjustment due to the differing size of the large cogs, which a spacer would not take care of. The adjustments are simple enough and should only take a few moments. I don't think it would be worth the trouble to try and match them up with spacers.