70mm wheel on 1.75 inch hub motored wheel


New Member
Local time
4:35 AM
Jan 24, 2008
I got an awesome set of birthday presents from my family and coworkers --

An Electra Amsterdam and a BD36 E-bike kit. Needless to say, it's been an amazing birthday.

The only problem is the BD36 kit uses a 1.75 inch tire width while the Amsterdam's uses 700x40c city tires. Any advice on how best to use this kit with this bike?

I could put a standard tire on the BD36, but I'm worried it would be too wide and rub against the fenders. I've contacted Wilderness Energy to see if I can exchange it for hub motor attached to a different width wheel, so hopefully that will pan out.

I'm assuming my last resort would be to have the hub motor respoked onto the 700cc rims? I'm relatively new to bike maintenance so I'd probably want to get that done at a shop.

Anyone else had a similar situation?


edit: I didn't have the tire specs right -- new to this bike thing.
Last edited:
Tire Size

Hello Knarx - you need to find out the rim width of the BD36 with a pair of calipers or simply a ruler. Once you have that dimension, go to http://www.sheldonbrown.com/tire-sizing.html and skip to the "Width Considerations" section. You will then know what size tires you can safely use on the BD36 rim. Keep in mind 1.75 Inch(s) = 44.45 Millimetre(s), so it sounds like you're only off by 4 mm. I would try using the smaller tire on the BD36. Good luck. -- John
Another option would be to take both wheels to a bike shop, and have the proper rim put on the BD-36 hubmotor.

This guy can sell you a set of spokes to convert your hubmotor to 700mm. Be sure to tell him which hub you are using.
So update on this project. I was planning to have the bd36 hub respoked for a 700c rim, but unfortunately the motor is too wide for my front fork. I'm going to put the kit on a secondary dedicated e-bike for now and keep my Amsterdam stock.

Thanks for all the help.
In the hopes of beating a dead horse to submission, does anyone know of a good electric hub motor that would fit a fork with narrower dimensions (i.e. 3.5 inches)?

The Crystallite motors seems to be much smaller, but I'm not necessarily looking for something that expensive.
Not all frames take kindly to this, but some NON-Suspension forks.. can be spread with the help of spacers/washers inside the forks as long as the motor axle is long enough to allow it.

Otherwise.. your plan B is an option ! hehe