Converting a gravel-bike


100 µW
Jan 20, 2024
Not sure what this means
Looking for help on converting a gravel bike into an ebike. I've only ever owned prebuild bikes and don't have electrical background.
This is the bike I'm looking to convert: Serious Gravix |

I'd preferably use a rear-hub motor, mainly because the cogs/chain of my middrive fat-bike seem to wear rather quickly and I don't want to be changing those. But realistically, I think in the two years I've had my current bike I've changed them once and they're not ebike specced parts. Therefore, middrives are not out of the question.

I've been looking at some kits but can't really see any hub-drives that would fit or perhaps I'm just not getting it. The rear fork dropout is 142mm on that bike as far as I understand and e.g. this kit E-Bike Conversion Kit 36V 350W Rear Motor Kit for Cassette with 36V13Ah Battery and Charger states 138mm. I don't know if the 4mm is important? Also, the bike has 11s cassette but I let myself understand that the mountainbike-type cassettes which I think the bike has, are as wide as 10s cassettes whereas roadbike 11s cassettes would be wider and not fit the wheel.

Since I had a hard time finding hub-kits, I've also been looking at this: Bafang 48V750W/500W bbs02 kit and 48V14.5AH Panasonic downtube battery with 5V USB BBS, ebike batteries, Bafang M620, Bafang M600, Bafang M500, Bafang M510, KT controller with but I suppose that motor lacks torque sensor which a midengine should have I think.

I'd rather not shop around multiple places and would like to either be able to get all necessary parts from a single place or a complete kit to my liking.

What I think I want:
-Must be shippable from EU.
-48v 350w or 500w motor
-battery that works in cold weather, subzero in celcius scale but not arctic - I'll run a fatbike when the snow sets in
-no throttle
-if middrive, the front chainring needs to be like 52t

Please give suggestions.
I don't know of any hub motor that will fit these round 142mm axles on newer bikes, except this one:
All-Axle Hub Motor - Grin Products - Product Info

Your main problem will not be axle width, but square axles ( most hubs ) won't work in a thru axle. Axle diameter is also different.
Ah, I didn't consider that at all. Thanks for the heads up.
I've also looked at the tongsheng motors which do have torque sensor as far as I can see, but all the kits that are sold with the motor include a horrible display and I'm not quite sure what would work with the motor/battery if I were to get the parts separately.
There are some long threads about the TSDZ2 system that include display compatibility posts over the years.

Note that some of the threads are about the open-source-firmware versions of that unit, and stuff about those doesn't apply to the OEM-firmware versions, so be sure which one you are getting before following thread/post advice.

There are also newer versions of a TSDZ-like system by a new company, not much is yet known about those as they're still changing things about it as they ship them, but there are also threads about these, toseven or to7motor, etc.

For any middrive, make sure that they're designed to fit the specific BB shell your bike has, and that they'll clear all the tubes and stays of your bike. And that you can live with the wide pedal stance (q-factor).