Electric assist.



  • The hub (or cassette) you have, and the range it provides is going to be a factor in the motor's ability to assist you. If the low range on your hub is different than someone else's, your results are going to be different than his would be.

    My Nexus-8 has a low GI range of about 12" so it has a fair ability to climb even with out the motor.

    As has been suggested, though, you are going to be a lot better served using a gear sensor with any motor, with that hub. The reason being, the SA generally requires you to reduce the load when you shift, to ensure it shifts correctly. (Just as an external gearing would be. There are types for each, IGH and External. Make sure you order the right one for your gear setup!)

    With a motor, that isn't going to unload unless you pause pedaling during your shifting. (Or tap the brakes, or some other method to interrupt the motor's output during the shift.) With the shift sensor, it reads the cable movement and treats it the same as a light tap on the brake handle would. (Lights the light, but doesn't apply the brake.) When the light lights up, it interrupts the motor for about 1/2 second to enable the hub to shift completely.

    If you buy the motor through Luna, they have motors with this sensor connector already installed. (Ask for this, though. They might have some that don't have the connector. Read the descriptions!) Any other branded Bafang is not going to have it unless the description specifically states it's there. Without this "third brake" connector, you need to buy a brake "Y" cable as I suggested above. I think I bought my "Y" from EM3V, but Luna has them now, I believe.

    It may even be possible to use another "Y" for supplying power to a working brake light. I've been toying with this idea for a while now, but can't seem to find a relay that has a 5V trigger voltage but handles 12V on the output side. (I've blown a few relays...) :(

    @PapaSkisNTrikes I hope your motor system works as you want it to. A lot of LBS's don't know much (or anything) about mid-drive motors other than some of the much bigger ones, in the 3KW range... There just doesn't seem to be a lot of market for many of the LBS's, or they are "purists" and not interested in the e-bike revolution that is happening now.

    Bafang motors are made in China and marketed mainly to Asia and Europe. They are picking up a lot more traction in the US, but there aren't a lot of US distributors. There were a lot of teething problems with US buyers early on. Companies like Luna went out on a limb and got a lot of these teething problems resolved. In other words, the Chinese company listened to the US market, and the results are the BBSHD motor.

    Luna Cycles has a direct factory pipeline from China. As a result, they have asked (and gotten) a few modifications that aren't available from other avenues. The third "brake" connector (actually they call it a shift sensor connector, but it is really nothing more than a brake signal.) is one of these modifications they have gotten. Another mod they asked for was the higher capacity MOSFETs all of the newer motors ship with. Luna even sells just the controller to modify an older motor to the better FETS for about $100.

    These guys sell a lot of these motors, know their stuff, and are a US based company, even though the motors are Chinese manufactured. I cannot praise them enough!

    If you are even remotely handy with tools, total time to mod a bike to electric could be done in a couple of hours. Maybe a bit more if you have to mount things like the dedicated brake handles, route the cabling cleanly, Put on cable extensions, etc. About the same amount of time to do this for a trike, unless you are doing a special build. (Like I did.)
  • I'm starting to think that buying the IGH version of the Rover was a mistake - too much stuff expects an external gear set. Maybe I should just switch to external.
  • I really like using the Nexus internal BUT, as you say, you have to work around it.
  • Externals also require you to unload a bit when you shift. And for that reason there is a gear shift sensor just for externals. (Second paragraph in my reply above mentioned them, too.)

    The only real advantage I can see for externals is, you can tailor make your gearing. IGH's have a lot of advantages, IMO.
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