SpeedsIn the early 1990s, the industry moved to 8-speed clusters with 130 mm spacing. 8-speeds were available in both freewheel and cassette hubs. As with the move from 4- to 5-speed, and from 5-speed to 6-speed, this required adding spacers to the right-hand end of the axle to keep the chain from rubbing on the frame.

In reality, the fancier parts aren't always the most suitable, in the same way that a Ferrari, while it is a great racecar, isn't at all as good for daily transportation as a Toyota -- there are practical issues of cost, reliability, serviceability and durability. With bicycle components, the performance gain with higher-end models is often minuscule. Remember, you account for 80 percent of the weight even if you are riding a rather heavy bicycle!All recent freewheels and threaded hubs, regardless of where made, use ISO threading. The older British and Italian standards use the same thread pitch but a very slightly different thread diameter, and are generally interchangeable. However, for strong riders and on tandems, it is best not to mix and match -- freewheels sometimes do strip the threads of aluminium hubs. A French freewheel may start to thread onto an ISO/British/Italian hub but will soon bind. An ISO/British/Italian freewheel will skim the top of the threads of a French hub and will slip forward if an attempt is made to use it. Do not force a freewheel -- you will ruin the hub. From 2004 through 2007, Shimano used aluminum bodies for the Dura-Ace 10-speed model. To avoid this problem, Shimano changed the spline pattern, making the aluminum spline ridges significantly taller for better support. The downside of this is that those hubs will accept only Shimano Dura-Ace, Ultegra and 105 10-speed cassettes. you don't need to buy the spacer, because you can use the spacer that came between the original flat 13 and the 14.) An additional complication is that "road" front derailer cages are shaped to fit well with a 52-53 tooth big chainring, while most current "mountain" front cages are shaped to fit with a 42-44 tooth big ring.

Except with 11 speeds, cog spacing is different enough from Shimano's that Shimano derailers and shifters may not work well with Campagnolo cassettes, and vice versa. It is possible to fudge compatibility in some cases where cog-to-cog spacing is similar. When discussing cassettes, the terms "Road" and "Mountain" are marketing terms, not technical ones. Old Chainrings, New ChainsThere is a lot of confusion about the compatibility of narrow 9- and 10-speed chains with older cranksets. Shimano says you should replace the inner chainring(s) with specially designated 9- or 10-speed ones, but then they're all too eager to sell you stuff, whether you need it or not. Rebuild the freewheel, so you can clean all the internal parts thoroughly. See our article on freewheel rebuilding.Campagnolo/Shimano 8-speed cassettes have different spacing , so you can't generally get good indexing using a Campagnolo 8-speed wheel with a Shimano shift system or vice versa. Shimano wants you to use one of its standard combinations, and offers a wide-enough choice to suit the needs of most cyclists, but you don't have to if you don't want to!