Dual hub e-bikes

[Wayners]

Can't find any information here on having two hub motors?
I read they are popular but not much information online.
250w both front and back. Maybe even two 350w. Did find a guy on YouTube with dual 350w over volted and looked brilliant running off one battery.

Anyone built one? Guess you could say there is no advantage and not legal, but two wheel drive. Hum?

 

[Woosh]

I think saneagle owned one.
Personally, I wouldn't trust such an arrangement.
If the front motor pulls more than the rear motor, you can create an unexpected rotation and you don't want your handlebars to do that.

edit:
even if the front wheel pulls less than the rear wheel, if the front wheel plane and the rear wheel plane don't coincide, they create a force causing the bike to steer in a way you may not expect. So the bike is OK until you make a slight movement with the handlebars.

 

[Az.]

Can't find any information here on having two hub motors?

What would be the purpose of such ebike?

You will drain battery much faster.

 

[WheezyRider]

It's been done. Trouble is the legal motor limit is 250W. So unless you can find two 125W motors you are all too obviously breaking the law.

 

[Az.]

I don't see a point of doing it really.
I suggest you finish installing kit you have, buy a good helmet and enjoy what you have for some time. No need to overcomplicate things.

 

[Wayners]

I don't see a point of doing it really.
I suggest you finish installing kit you have, buy a good helmet and enjoy what you have for some time. No need to overcomplicate things.

Yes. That's the plan.
Just asking questions and doing lot's off reading online.
Finding it all very interesting.

 

[Sturmey]

The dual hub setup works great on hills. I have used an additional front xf07 front as a sort of booster motor with a yose 350 rear for steep hills. No steering problems. The xf07 when idle has practically no friction.
Its technically a very good and robust solution for steep hills. (imo) Its a pity its not legal.

 

[portals]

Given the losses using 2 motors wouldn't you just be better off with a more powerful rear hub to get up these hills given 2 motors wattage exceeds legal limit anyway?

 

[Sturmey]

Given the losses using 2 motors wouldn't you just be better off with a more powerful rear hub to get up these hills given 2 motors wattage exceeds legal limit anyway?

The losses with two smaller motors are not necessarily greater. But you are probably right in that if a single suitable hub motor that could supply the same torque as the two smaller motors was readily/easily available, then this would be a better option and would be less conspicuous. Can you recommend me a reliable 80nm rear hub for 135mm dropouts?

 

[guerney]

The dual hub setup works great on hills. I have used an additional front xf07 front as a sort of booster motor with a yose 350 rear for steep hills. No steering problems. The xf07 when idle has practically no friction.
Its technically a very good and robust solution for steep hills. (imo) Its a pity its not legal.

Did you use one or two batteries? While the second motor system isn't powered, the bike is simply carrying luggage, and therefore legal until you power the second 250w hub?

 

[soundwave]

 

[Wayners]

This is what I watched

 

[Az.]

Its technically a very good and robust solution for steep hills.

What kind of steep hills? Off road?

 

[sjpt]

I think saneagle owned one.
Personally, I wouldn't trust such an arrangement.
If the front motor pulls more than the rear motor, you can create an unexpected rotation and you don't want your handlebars to do that.

edit:
even if the front wheel pulls less than the rear wheel, if the front wheel plane and the rear wheel plane don't coincide, they create a force causing the bike to steer in a way you may not expect. So the bike is OK until you make a slight movement with the handlebars.

Does all of that apply to front hub ebikes? The front motor is likely to pull more than the rear motor (rider).

Despite the disadvantages of front hub I've found it very effective on our tandem, and the two wheel drive aspect has often saved us from slipping on wet grass slight uphills. Of course, the tandem has better weight distribution between the wheels than a solo.

It's been done. Trouble is the legal motor limit is 250W. So unless you can find two 125W motors you are all too obviously breaking the law.

I think that two motors breaks the law even if they add up t0 250w or less.

 

[Sturmey]

What kind of steep hills? Off road?

On road. The local cycling club put up a sign which claims its 15.7% max climb using 'strava' as shown on my avatar. Cyclotravel's (which I think uses the ordnance surveys 10 meter contour lines and may not be as accurate on short stretches) is as shown in photo below which roughly tallies with strava.
This hill is between where I live and an local adjacent village.

 

[AndyBike]

They only pick Guy Martin to present these things because they know he's got a lot of form for falling off. A good crash = good viewing.

 

[flecc]

Guess you could say there is no advantage and not legal, but two wheel drive. Hum?

Any ordinary bicycle with a front hub motor added is two wheel drive.
.

 

[Wayners]

Any ordinary bicycle with a front hub motor added is two wheel drive.
.

Yeah. I was thinking that. People add 400w with legs I read somewhere

 

[Az.]

On road.

So far my 250W front hub managed to climb all hills (off road is a complete different story).

In case of any problems I guess I would rather choose single more powerful motor rather than dual hub solution.

 

[saneagle]

The losses with two smaller motors are not necessarily greater. But you are probably right in that if a single suitable hub motor that could supply the same torque as the two smaller motors was readily/easily available, then this would be a better option and would be less conspicuous. Can you recommend me a reliable 80nm rear hub for 135mm dropouts?

Two small motors are slightly more efficient than a single small one, and about the same as a single big one. Don't ask me why, but that's the result of the test I did over a couple of hilly rides, when I did lots of experimentation with two motors before deciding that one more powerful motor is better than two with less power because of other reasons, like expense and complicated installation. Basically, there are no tangible advantages to using two motors other than better grip on slippery surfaces.