No announcement yet.

Compatibility issues going from a 9-speed to a 7-speed?

  • Filter
  • Time
  • Show
Clear All
new posts

    Compatibility issues going from a 9-speed to a 7-speed?


    I'm new to e-bikes and I'm trying to build my own. I'm wondering if there are any compatibility issues going from a 9-speed bike to a 7-speed rear wheel.

    Thank you,

    9 speed chains are a bit narrower than 7/8 speed chains and spacing between rear cogs is closer on 9 speeds so...
    if you want good indexing on the 7 speed setup you might want to replace the rear shifter and chain with proper 7 speed units. I’m thinking the chainrings you have up front probably can be used without a problem.



      9 and 7 speed are entirely different drivelines but that doesn't mean you can't switch, just that everything needs to change - derailleur, chain and shifter for sure, chainring maybe

      OTOH you may be able to limit your 9-speed to only 7 gears using all the existing components - that's super easy enough to try


        Ah i see, perhaps it'd be easier to get a 9-speed even if it is a bit more expensive. Do you guys have any recommendations for any 27.5" 9-speed rear wheel drive motors? Budget is around 450$ for everything else besides the battery.

        I found this one: but the seller seems a bit sketchy from the reviews. Any advice would be appreciated! Thank you!


          If you are doing a DDH rear hub motor you may find room a problem. Mine came with a crappy 7 speed cluster and I couldn’t get it to fit in my triangle with all 7 gears working. Found a nice 6 speed Shimano cluster from l.b.s. And it works pretty well...wish they still made the old 14-28 5 speed units. Some days I only use one gear. When you consider that even a little 500 watt motor can sustain 5times more than a strong human peddler you can see real fine tuning of gearing is a bit unnecessary.


          • AZguy
            AZguy commented
            Editing a comment
            Elite bikers put out >400W... I'm confident I can do more than 100W continuous easily, significantly more in bursts, and I'm old with a missing leg... I've "measured" it in the past by setting the controller into constant speed mode and watching how much the power drops on the batt-man when I go from clown pedaling to pumping...

            I clearly have different needs with gearing too. I've got an 11-46t rear cassette that is optimal for me. I don't use the very lowest or very highest gear every ride, more like every other, but the ones in between are used every time I'm out... I've tried less ratio and they weren't enough however I don't see much advantage to having more... again, for me...

            500W is enough to get around on my mid-drive but even 750W on my rear hub lacks and it's nice to have more than 500W but these days I don't use more than that on about half my rides on the mid-drive and I sure like that there is more available...