I have a 9 x 3 speed mountain-bike. The derailleur got broken (and was since lost), I'm trying to find a new one. What do I need to go by to ensure I get a good fit? The rear-casette (sprokets) range from 11 to 32 teeth (there are 9 of them). Is this enough information?


It was noted that I also need to know the make of the gear-shifter, the one I have is SRAM


There are not that many firms that produce this type of equipment. The most popular one is shimano, with smaller competitors like SRAM and Campagnolo. SRAM gear is fully compatible with the Shimano one. Camagnolo has its own and is incompatible with Shimano or sram one. Almost all bikes have shimano gear, so I'd suppose you have the shimano stuff.

You need to know how many gears your cogset has and is irrelevant, how many "teeth" the cogset has.

shimano/sram has different quality lines and differnt sizes. What you need to know is basically, how many gears you had before. These systems vary between (1) up to 8 gears, (2) 9 gears, (3) 10 gears ( and (4) 11 gears?). Shimano and other manufacturers tried to pack up more gears as years went, therefore they had to pack more cogwheels in the same amount of space, therefore all these systems have exactly the same width, and therefore they are completely incompatible between each other, i.e., 8 gear thingy will not work with 9 gear cogset and vice versa.

Once you know the number of gears (in your case it is nine), you'll have to choose the quality line. This varies from Acera (cheapes) to XTR (most expensive). Up to XT line, you'll get both the weight and the stability increase. Above XT shimano and the others are trading weight for stability.

If you let me know the price of the bike, I'd give you a suggestion for the gear :)

Have fun!

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  • Hi thanks for a nice answer, I noted my gear-shifter is 9-speed SRAM. The frame is a medium-to-upper range, of Norwegian origin (Nakamura Complite, by Intersport). Any specific suggestions for the derailleur would be welcome :) – Rob Hoff Apr 10 '13 at 14:46
  • If the bike is in the medium--upper range, I'd go for Shimano SLX (costs 40 Euro in Europe) or XT (costs some 55Euro). I would not go lower (Deore, costs 25 Euro) because you'd be using this part a lot (you'd be using it the first thing to make your ride harder or easier). Sram rough equivalents are: X-7 = SLX, X-9 = XT, although people tend to have different feelings. Personnaly, I rode SLX some 5000km then I switched to XT and haven't seen a huge improvement. Frankly I haven't seen a huge improvement from deore to slx either, but I would not recommend deore. – arthur Apr 10 '13 at 19:35
  • @arthur It's always been my understanding that Sram and Shimano cassettes are interchangeable, but you have to run Sram derailleurs with Sram shifters and likewise for Shimano. – jimchristie Apr 11 '13 at 6:11
  • @area5one The frame is irrelevant. The only compatibility issues that you have to worry about are between the number of gears and the brand of the derailleur and shifter. – jimchristie Apr 11 '13 at 6:12
  • @jimirings I have really got personal experience for shimano cassete with sram derailleurs (or vice versa). Friends of mine have tried such combinations. Some people say that's not a problem whatsoever, some strongly disagree. To be on the save side, then sram sounds a better choice – arthur Apr 11 '13 at 7:44

You'll also need to know the manufacturer, so that the shifters will be compatible. Most likely it's Shimano, or SRAM. It should be written somewhere on the shift levers.

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  • Hi, thanks for the comment, I noted the gear-shifter is SRAM – Rob Hoff Apr 10 '13 at 14:47

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