LHD for a motor for £0

Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
I've made the often repeated mistake of starting another project without finishing the last one. It's not the first and is unlikely to be the last time I do that. This one is for a trike with electric assist. I have an electric scooter with a 600w 24v system that is going to donate said system to my next trike. I therefore need a means of driving the rear wheel. A LHD sprocket seems the best method to avoid driving the motor when pedalling. Flip flop hubs are available and LHD sprockets but I wanted to avoid buying those and relacing the wheel so here goes:-

Firstly take an old steel rear hub and cut it down to this on the drive side with it's freewheel thread.


It's useful if it was a 36 spoke one because next you align a disc rotor and drill through. The 6 holes almost align with 6 on the hub.



Screw a regular RHD freewheel onto the hub (wrong way on so it works when used on the left the left) and take a right hand threaded bottom bracket cup - one of these:-



And screw it into the freewheel until it buts upto the hub like this:-



Next screw on the locking ring that came with that cup and grind the top off the cup down to the ring.



It will go from looking like the left to looking like the right.



With the freewheel on the hub and the ground down cap all assembled you now need to weld the hub to the cap on the inside. By welding them assembled you ensure that the bits are perfectly aligned - even the threads. You should now have a hub that looks like this:-



The freewheel will now go back on with enough threads left over for the locking ring to go back on.



I intend to use two small tack welds on the locking ring to prevent the freewheel unscrewing as it'll try to do that against the ring rather than self tighten to the hub as in it's intended use. I thought about using two locking rings but decided against as I've seen that system not work satisfactorily. I also didn't want to glue the freewheel on as I'd never get any bolts in or out of the flange due to clearance. The assembly can be bolted to a disc brake mount either with or without the disc then the locking ring tacked to prevent loosening. It's not going to need to come off regularly so having to kiss the tacks with a flap disc isn't any major issue. Depending on axle nuts etc you may need to bore through the assembly to allow it to pass over them.

You now have a LHD for a motor that is perfectly aligned and wobble free.
 
Joined
May 31, 2013
Messages
2,297
Location
South Benfleet, Essex, England, UK
And there was I thinking you would buy a "ready-made" ;)
 
Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
Alas that I had known they even exist! A fixed sprocket at the wheel involves less splaying of the rear frame so may be a better option and RHD freewheel at the motor end is self-tightening. However given the smallest regular freewheel is 13T I'd need a 28T, or so, fixed one at the wheel for my application and the only ones I can find at anywhere near that size use non cycle std chain so I'd have another cost there. With the freewheel at the wheel end I can use a 20T one and a 9t fixed at the motor. Both are easy to obtain.
 
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