Say you’re upgrading on a budget and can replace a few parts at a time and still have a perfectly functional set of 9-speed derailleurs. Can you use them with 10-speed shifters and gearing? We got this question from a reader, so we turned it over to the heavy hitters in the mountain bike drivetrain category, SRAM and Shimano. Here’s what they had to say regarding mountain bike drivetrains:
MORGAN @ SRAM: For the rear, no. The cable pull is different for the 10-speed rear derailleurs and the 9-speed rear derailleurs won’t line up properly with the cogs when used with a 10-speed shifter and cassette. A 9-speed front derailleur will work, but it’s not optimized and may result in more chain drops or slower shifting -or no shifting at the extreme ends of the cassette- because the gap between plates is larger than what’s required for a 10-speed chain. The cage is also shorter if you’re viewing it from the side because it doesn’t have to work with as large of a chainring as what’s typically found on a triple.
JOE @ SHIMANO: Not really. Anything with Mega9 on it was designed to work together as a 9-speed system, and anything with DynaSys on it is 10-speed only. The cable pull ratio is different. The 10-speed stuff pulls a lot more cable, and the lever arm on the rear derailleur is much longer. We designed it this way so when you do your shifts from the smallest cog all the way up, the lever feel is the same all the way through the range. Also, the 9-speed was more of a universal system, too, but the DynaSys is an exclusive mountain bike system.
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