Add a cassette to Nexus IGH

Pretty apparent I don't know what I'm talking about but is it possible to add a 2 or 3 cog cassette to a Rover with Nexus 8?
I'm still studying appropriate chain wheel for BBSHD equipped Rover tandem. Performance varies depending on whether my stoker/wife is pedaling or cruising (which is allowed ) or whether she is on board at all. Gear changes at the back end of the chain could help. I've done no math on this :-)


  • edited March 10
    yes, as far as cassete addition goes if in diy mode. this would involve converting the driveline to a mechanical mid-drive configuration: crank-turner up front feeding a mid-mount derailler and gear cluster which in turn feeds the rear igh.

    if just interested in changing out the nexus sprocket for lower gearing, cheap and easy enough to do or have done. sheldon brown gear-inch calculator takes care of the math for both gear-inches and mph expectations.

    depends on the nature of your desires. dropping the 32-tooth chainring in favor of a 30-toother suggests you are more concerned with low-end than high-end performance? if so, more practical to install a larger sprocket on the nexus ($8) then go the chainring route. this will lower your max speed.

    if you desire lower gearing while maintaining current top speed, might be easiest using the nexus-11 although it does not seem to have the same bulletproof regard as the nexus-8. this would increase your presumed current gear range of 18-57 gear inches to 18-75 g.i.

    to get honest hill climbing with the nexus-11, a 20-tooth nexus sprocket would give you a range of 15-60 g.i.
  • Thanks for the explantion. I too am learning. I have a Rover i8 that soon will be a tandem, and was thinking about adding more gearing for more speed.
    I have a lot a learn
  • still in the learning mode, meself. pretty much a tryit kinda thing with or without electric assist.

    smaller the sprocket on the nexus, faster you go. 16-tooth is smallest readily available. that leaves the front sprocket, if you have the knees, to gain speed from a mechanical perspective. no post on the rover for mounting a triple chainring but same gearing range can be had with the nexus plus patterson, efneo, or schlumpf single sprockets up front.

    with electric assist, given motor winding and controller setup, voltage controls the max speed. one thing to check is whether the leads from your battery get warm - if so, voltage drop is robbing your motor of power. depending, etc, bigger chain ring up front should have you going faster.

    excellent electric motor education at - wealth of information there. great customer support as well - justin set my heart at ease in an email today saying 24 volts should work fine on the 9-continent geared wheel i just ordered for the delta.

    had such a deal - 20% off on sealed lead acid batteries, free shipping. question answered was if the 9c controller, with its 36-volt+ controller would work with my intentions. yeah, he said, if 9c has maintained spec. the chart he sent shows 120 mile range at 15 mph for the 55 amp-hour deep-cycle monsters due in.
  • JamesR, I'm reading you carefully and appreciate it. I've been from 32T stock, to 42T on Bafang BBSHD, back to 30T Mini from Luna that has offset to fit BBSHD. Since I want to pedal for exercise and use the assist for steeper hills (my stoker has health issues and may or may not be pedaling at the time), I'd really like multiple ranges ahead of the Nexus. I'm told I can't use multiple chain rings on BBSHD so I wonder if I could do 16/20 cassette driving Nexus. Dreaming?
  • Hope to take the tandem to shop Monday for some tinkering and will pose some of this to head tech there.
    If shifting at front or rear is not possible, I may settle for mid 30's tooth chain wheel. I have NOT reprogrammed BBSHD ... maybe that's next.
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