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I am trying to refurbish an old trekking bike from the early/mid 1990s. Current components of 3x7 drivetrain are as follows:

  • crank: Shimano Exage FC-M320 46-36-26
  • chain: unknown
  • cassette: 7-speed 28-11 Shimano (specific model unknown)
  • rear derailleur: Shimano Altus (silvery cage, max. 28T, specific model unknown)
  • front derailleur: unknown (Shimano-like model)
  • shifters/triggers: Shimano Twist Shifters (specific model unknown)

As component availability is problematic (due to the pandemic and the older 3x7 speed components), I am considering mixing SRAM and Shimano components. SRAM cassettes are generally considered being compatible with the Shimano ones. However, this does not seem to apply for the older 7-speed models. Therefore, I decided to use a Shimano CS-HG41 cassette instead of changing the complete rear wheel hub to a more modern one.

As the rear derailleur should be replaced as well and I want to transition from twist shifters to "finger shifters" (like the more modern ones), I looked for suitable Shimano 3x7 shifters which do not seem to be rarely available. SRAM ones seem to have a better availability and I decided to go with either the X.3 or the X.4 models. In addition, a X.3 or X.4 rear derailleur is also available. Unfortunately, no 3 speed SRAM cranks seem to be available and I would either keep my old Exage FC-M320 or go with an Acera FC-M361.

There does not seem to be many information about the SRAM/Shimano compatibility for these rather old 3x7 setups available online and I was not able to clarify the component compatibility completely. I tried to get some hints from my local bike mechanic who was not sure as well and suggested to stay within one manufacturer (either Shimano or SRAM). However, this does not seem to be possible due to parts availability.

Would the following parts be compatible with each other?

  • crank: existing Shimano Exage FC-M320 46-36-26 or new part Acera FC-M361 42-32-22
  • chain: Shimano CN-HG40
  • cassette: Shimano CS-HG41 28-11
  • rear derailleur: SRAM X.3 7-speed
  • shifters/triggers: SRAM X.3 3x7

Does anyone have compatibility information about these older 3x7 setups?

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    Why do you not use the chance to upgrade to 3x8 or even 3x9 where part availability should be better?
    – Michael
    Feb 5 at 13:42
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    For 3x8 or 3x9 a new rear wheel hub would be required which is also hard to get these days and all the spokes need to be re-done as well.
    – albert
    Feb 5 at 13:43
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    If the rims are steel upgrading to alloy wheels might be good and not too expensive idea with 8-9-10-11 hubs as a bonus. With existing 90s alloy rims check the brake track thickness anyway!
    – Carel
    Feb 5 at 15:45
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    Yes, your proposed combination will work. Someone else is welcome to explain why.
    – Noise
    Feb 5 at 16:01

1 Answer 1

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SRAM rear shifters are not compatible with Shimano rear derailleurs in almost all cases. A Shimano shifter is incompatible with SRAM rear derailleurs. The reason for the incompatibility has to do with the amount of cable pulled by the shifter not matching the derailleur's actuation ratio, which is the amount of movement per mm of cable pull. Because you are using SRAM X3 shifters with an X3 derailleur there is no issue here.

The SRAM-Shimano incompatibility does not extend to the front drive train where it's common to see a Shimano front derailleur in a set-up that's otherwise SRAM. This is marketed as a "mountain mix" of components. Front derailleur actuation ratios are not commonly published, but for the purpose of this answer, suffice it to say that the SRAM front shifter should work just fine with your front derailleur. Obviously it needs to be a three speed shifter for the triple front chain wheel.

Likewise, the Shimano crankset and rear cassette will be fine in this system. Spacing between cogs of a Shimano cassette and a SRAM cassette are the same. SRAM cassettes up to 10 speed mountain, use the Shimano-style, HG (HyperGlide), splined freehub interface as Shimano and other cassette makers. With the advent of 10 speed, SRAM began to use their own proprietary freehub body, termed XD, on which only an XD cassette can be mounted. To note: SRAM continues to make 10, 11 and even 12 speed cassettes that will fit on HG freehubs and these, too, are compatible within Shimano drivetrains. (There are issues relating to the width of the HG freehub body and use of spacers placed on the hub body prior to mounting the cassette that need resolved before one can definitely state a certain cassette will work on a certain freehub). One thing you'll want to note about your rear wheel's freehub is whether there is currently a spacer placed before the cassette. If present, you'll want to keep that there to use the new 7 speed cassette. If there is not a spacer present now, it's because you have a 7 speed freehub body, which obviously works for a 7 speed cassette. You will not be able to mount a higher (8, 9, 10) speed cassette on a 7 speed freehub however.

Most all brands of chains up through 10 speed are compatible in either a SRAM or Shimano drivetrain. One must pay attention to the "speed" of the chain and use the one that matches the speed of the rear drivetrain (cassette). As we increase the number of cassette cogs, chains have narrowed their outside diameter to fit in the narrowing inter-cog spaces. Six, 7 and 8 speed chains are all the same width, and, technically, one could use a narrower chain (in your case a 9 speed chain) with good results as long as it's a one speed difference. More than that runs the risk of poor shifting and impossibly jammed chains should derailment occur.

I don't know where you're located, but there is not a scarcity of 7 speed parts in online market places. eBay and others have many offerings, and if you live in an area where bicycle coops exist (or where there is a used part market), 7, 8 and 9 speed components are the most prevalent.

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    Note that SRAM practically invented itself by making Shimano-compatible parts in the 7 and 8 speed era. For example, you can find millions of bikes that pair the SRAM MRX Comp 7 and 8 speed right shifters with Shimano rear derailleurs. Mar 11 at 17:00
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    @Nathan Knutson that's a great point. I struggle with how to explain that early SRAM products were compatible with Shimano parts. I choose to ignore the fact to reduce confusion (my own included). When I do include something, it typically addresses the front drive and marketing term, "mountain mix" to describe a drivetrain with SRAM and Shimano parts.
    – Jeff
    Mar 12 at 6:22

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