Looking for suggestions for a low-ish speed, high-ish torque front hub motor to go with existing 48v kit

[emjay]

Hi folks,

A couple of years ago I did a rear hub drive commuter bike conversion, detailed here:

Q128C 25mph fast hybrid commuter build/ride report

Executive summary: here's a pic of the more-or-less finished bike: 25mph on the flat @ ~600W, 20kg bike weight. Warning: long post comming up :-) This is mostly a brain dump of everything that I did for my recent build in the hope that it will be useful to somebody else considering the...

www.pedelecs.co.uk

I ended up with a 36v rear hub motor running at 48v thanks to the excellent advice from the forum

Now my biking needs have changed! That bike now has no electric parts, and is currently fitted with a follow-me tandem for pulling my wee one around on her bike. This is exhausting as the coupling weighs a ton, so I'm wondering if I could use my existing kit and fit a front hub motor to use with my battery, controller, etc. It would have to be a front motor as the tandem coupling takes up the rear dropout. I would also want something with a lot less speed than I currently have (no plans to pull my kid along at 25mph!!) but preferably more torque for dragging all that weight uphill. The front forks are alu, so I'd be using a beefy brake-bolt-mounted torque arm (I have plenty of spares left from the original build).

Is this idea possible, and if so can anyone recommend a suitable motor?

 

[Benjahmin]

With Ali forks, check that the drop outs are in board on the fork leg. Otherwise the motor may not clear the fork leg (assuming suspension forks). Sometimes brake caliperslarger can foul on motor casing but this is cured by fitting a larger disc and mount adaptor.
Apart from that almost any motor will do. A 36v motor run at 48v will give approx. 30% more torque (helps to drag a heavy lump up hills), but the rpm will also be proportionally higher. So give us the wheel size and preferred modal speed (15mph?) and you'll get more concise information.

 

[emjay]

With Ali forks, check that the drop outs are in board on the fork leg. Otherwise the motor may not clear the fork leg (assuming suspension forks). Sometimes brake caliperslarger can foul on motor casing but this is cured by fitting a larger disc and mount adaptor.
Apart from that almost any motor will do. A 36v motor run at 48v will give approx. 30% more torque (helps to drag a heavy lump up hills), but the rpm will also be proportionally higher. So give us the wheel size and preferred modal speed (15mph?) and you'll get more concise information.

Many thanks for the reply - I should have mentioned this in my post - wheel size is 700c and yes, probably 15mph would be a good target speed. No suspension forks; the bike is a kind of flat bar hybrid.

 

[vfr400]

Most 700c forks aren't strong enough for a high torque front motor. Show us what you've got. Also you'll have problems with traction.

Can't you make an adapter for the coupling? For most, all you need is a plate with two holes or a drilled torque arm.

 

[emjay]

Thanks, I'll get a picture. The issue is that the coupling slots into a custom QR skewer and has to be secured from the outside, exactly where the cable comes out from a hub motor.