Originally Posted by
Bud Bent
Swapping cassettes is fine. It's shifters and rear deraillers that you have to worry about compatibility if you mix and match. SRAM numbered shifters (X.7, X.9, X.0, etc) are not compatible with Shimano rear deraillers, and vice versa.
Same thing on the road groups. Keep the shifters and derailleurs the same brand, but everything else can mix-n-match.
Chiming in on the chains thing, I've used Shimano, SRAM and KMC. All my bikes (8-speed Sora, 9-speed Ultegra/Dura-Ace mix, 10-speed 105/Ultegra mix, and 10-speed Ultegra) seem to like KMC the best. They seem to shift more smoothly, run a lot quieter and like SRAM, they come with a reusable master link. Better still, they can be half the price, if you know where to shop.