Question: I’m riding a Specialized Roubaix Pro with Ultegra Di2 electronics. I have two wheelsets that I switch back and forth with – one clincher and one tubular. I’ve just installed an 11-speed cassette (Shimano 11-32) on the tubular wheelset, replacing the 10-speed Shimano 11-28. My clincher wheelset has a 10-speed cassette (Sram 11-32), which works well.
My question is, will a Shimano Dura-Ace CN9000 11-speed chain work with both cassettes (10 speed & 11 speed), or will I need to add a cog to the Sram cassette? From: Fred B.
Answer: 11-speed chains work pretty well for 10-speed cassettes, so you have little to worry about there. My concern is that you will have issues with your rear derailleur limits and indexing when switching back and forth between wheelsets.
If I could make a suggestion it would be to install an 11-speed freehub body on your clincher wheelset along with an 11-speed cassette. You may still need to make some tweaks to your rear derailleur indexing and possibly limit adjustment when making the swap, but you’ll have full compatibility. Wheelsets using different rear hubs usually don’t quite match up perfectly with respect to chain line. On one rear wheel the cassette will sit further outboard compared to another rear hub, even when the cassettes are identical.
The pro solution to this problem is to shim out the cassette on the rear wheel (1) where the cassette sits inboard relative to the rear wheel (2) on the other wheelset. This is done by placing shims behind the cassette (on wheel 1) to move it outboard to match the chain line of your other rear wheel (wheel 2). With the shimmed setup you won’t have to make any derailleur adjustments when swapping wheels and you’ll have worry free shifting come race day.
Welcome to our Ask a Mechanic column where our expert mechanics Daniel Slusser and Greg O’Keeffe answer your bike maintenance questions. If you have a question for us, please post it on the Art’s Cyclery Facebook Wall or e-mail Daniel directly at firstname.lastname@example.org.