Motor & wheel size?

[Tinker]

I've just discovered that a local breakers yard has a number of e bike motors, they all come off bikes that have been damaged in rear-end shunts when being carried on the back of caravans/cars etc (I'm in a popular tourist area).Most are still in the rim and undamaged, these ones are mainly rear-wheel it appears that the front rims get damaged/bent far easier and they strip the motors out of the rim.
My question: Apart from the amount of spoke holes is there a difference between say an 8-Fun in a 20" wheel & a 700c wheel?
Very few of the motors I've seen are actually marked in English, often I can only make out a voltage, apparently he reckons on getting around 20 a year & gives them to a 'Mate' who knocks them out at car-boots 'up London'

 

[Deleted member 4366]

Some versions have different speed windings, but most new ones are around 201rpm 36v or about 18mph ,so get a couple, build them into wheels, and if one is better than the other, keep it and sell the other one on Ebay.
You have to decide what speed you want to go. A 24v one at 36v will do about 28mph, but have not so much pulling power, so better for a light-weight rider and bike. If you want to put one in 20" wheels, then you want a 24v version to run at 36v to be sure you get enough speed. You can run a motor at more or less any voltage: What's stamped on it has no real meaning. It only gives an idea about the speed it will go at that voltage, so a high speed 36v motor can be identical to a low speed 24v one, or another example, a 24v motor in a 26" wheel can be the same motor in a 16" wheel run at 36v and the bikes would go the same speed although the 16" wheeled bike wiould climb much better because the motor will be spinning faster.

In summary, if you want one for 26" wheel look out for a black and silver (my favourite) 36v Bafang for 18 mph; If you want 20", or high speed, get a 24v one. All this assuming no RPM stamped on the motor.

 

[jerrysimon]

Nice find.

Jerry

 

[Tinker]

Thanks for the replies, i'm tempted to get one to stick on my 20" folders front wheel to match the existing 36v 250watt rear wheel & try a 2 wheel drive for myself.
Hopefully I can swap an old tractor battery for a motor

 

[jackhandy]

Must call in to Henry's scrap yard later this week ........

 

[Deleted member 4366]

Don't forget that you need a 24v one for 20" wheels

 

[Tinker]

Don't forget that you need a 24v one for 20" wheels

It's got 36v 250watt rear wheel, what happens if I use the same?

 

[Deleted member 4366]

A normal 201rpm 36v motor in a 20" wheel will give about 13mph - maybe 15mph with a fully charged battery. It won't make much power above 12mph.

 

[neptune]

This is a classic case of useful things being melted down for scrap. Even with the current high scrap prices, I doubt if a scrap motor wheel is worth £10 as scrap. Even if only the motor is re-usable, an enthusiast would gladly pay £20 to £30. The problem is that scrap yards are not so approachable as they once were, what with the need to show ID, and health and safety regulations. If a bike is bent and crunched in an accident, it may be possible to save the motor and most of the electrics, plus tyres etc. What a waste.

 

[Scimitar]

I fully agree. It burns me to see perfectly useable parts going into the scrap bin like that.