Currie Electrodrive kit, 7 speed hub required?

[akathatman]

The advice given on fitting these outboard Currie kits is that they require a 26" or 29" wheel with 36 spokes and a 7 speed freewheel hub.
Does anyone know why a 7 speed hub is specified and a 5 or 6 speed hub would be unsuitable? The completed wheel with kit requires a 140mm spacing between the lugs and I was wondering if having fewer gears would reduce this closer to the 135mm spacing on the donor bike.

 

[Deleted member 4366]

I gues that they're worried about spacing because their kit is installed referencing the LH side. I guess that as long as you apply aappropriate spacers so that the drive is neithe squashed noor flopping about it should be OK, then you have to adjust the spokes to get the rim central.

Why are you interested in a Currie kit when there's loads of cheap hub-motor kits that'll be loads better?

 

[flecc]

7 speed is the maximum for width, but you can have anything from single gear to 6 gears instead.

As d8veh says, you would be much better off with one of today's hub motors, very much more reliable, quieter and more efficient than the ancient Currie design, which stresses and can break rear wheel spokes with its crude drive adaptor.

 

[akathatman]

Thank you both for clearing that up. This has been more of a cheap, fun project for me than a serious attempt to build an efficient ebike. I wanted to prove to myself that I would find regular use for a bike before committing to a better and more expensive option and it has served this purpose well. I have to say that although very old tech this 400w version of the motor is torquey and quite a capable hill climber. I've been careful not to engage the motor until reaching walking speed and avoid the sudden stress applied to the spokes caused by starting from zero...so far so good.

 

[flecc]

They are indeed capable, indeed the original 900 watt one decades ago was lethal, at least until it burnt out, which wasn't very long!

The current more sensible one is certainly one quick and low cost way of sampling e-biking with an existing bike.