Dual independent motors - switching between legal and illegal motors? Legal?!

[alban]

Hi
I saw this idea mooted in a thread somewhere here. Flecc said that theoretically a powerful & 'illegal' hill-climber motor could be added to the front of an ebike in addition to a road-legal motor on the back - as long as there was one battery and a switch. When encountering steep hills off-road it would be poss to engage front motor only. Sounds a good compromise but how feasible for a relative novice to build using a standard conversion kit - and is it really 'legal'? Range isn't that important to me (6miles OK), or top speed, but great hill-climbing is.
It needs to be legal as my leisure journeys are sometimes on the road but off-road requires a lot of help up hills.
There doesn't seem to be a ready-made ebike that fits the bill due to the legal power cut-off point which makes no allowance for weight or health of rider. Thinking of a 20" wheel folding 'mountain bike' with dual suspension to get more mechanical advantage. I presume the added weight would be 3Kgs or so?
Thanks.

 

[flecc]

I don't think I implied it was legal to use an illegal motor on the road! If the switch is easily accessible and under rider control, it's bound to be illegal. I remember posting about having an illegal second motor for off road use, but the switch for that should not be accessible while riding and it would be best inside a box that had to have a cover removed to change over the motor used.

Alternatively, a crank drive bike using the gears for the motor can give the best of both worlds, steep hill ability with full legal speed on the flat, though at the cost of slower climbing.

Basically any illegal motor will always be illegal for on road use, regardless of whether it's for hills.
.

 

[banbury frank]

Hi

Our single motor already is electronically limited to 15 mph and 250 watts Nominal

But if you fit a simple switch to the controller you can switch between low power and high power ( speed 28 MPH + ) 1,500 watts using a 26 inch rim

All our kit are now 48 volt with 10 Ah battery's or 15 Ah battery's

we have fitted a motor in a 20 inch rear wheel It was used on a ice recumbent trike but we used a different winding giving us 12.5 rpm per volt

Rear wheel including motor 7 kilos

Battery 10 ah 4.5 kilos



Frank

 

[alban]

No, Flecc, you didn't imply that an illegal motor was ever legal on the road.
I can see that a quick switch would be viewed with suspicion but yes, one that required a dismount to change so that I could still relatively quickly switch to the road legal one for any road journeys on the route or the hill-climber for steep hills. So the idea of such a switch would in principle be within the realms of legality? (I suppose it's probably not been clearly ruled on).
Crank-drive still requires a fair bit of rider pedal effort from what I've gleaned here.
Thanks

 

[flecc]

With two legal motors I suppose which you use could be legally under your control while riding if the switch was a two way changeover one, switching the current of the single battery to whichever motor you chose, it then being impossible for both to run together.

Clearly your usage could then only be legal, but the legal status of the bike might still be in question. To be legal, technically every e-bike should have a manufacturer's plate in clear view, stating some details like the bike's weight, battery voltage and motor wattage. With two motors fitted the two motor bike would exceed the fitted wattage figure.

However, the fact that e-bikes are almost never fitted with the legally required plate emphasises that it's really only necessary to keep to the main provisions of the law and the chances of trouble are vanishingly small. So two legal motors with a changeover switch should in practice be safe to use with very little chance of challenge. Indeed, one of our members runs a twin hub motor machine and has never had any problems in Norfolk.