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If you've had the misfortune to drop a battery you'll know how readily the case cracks, particularly at the edges. The cracks can be often be healed with a clean tipped soldering iron, gently "welding" the parts together. These joins will lack strength though, so if a large part of an edge is cracked, it needs to be strengthened. An effective way to do this is with an outdoor grade of Duct Tape, a.k.a. Gaffer tape. I've got one battery repaired like this years ago still working perfectly ok. To view some images of cracked and repaired casings, use this link to my Torq website.
A couple of years ago, after a long period of trouble-free use, our 4-spd Nexus hub worked loose. When I accelerated hard, it twisted in the drop-outs, smashing the anti-rotation washers and bending the frame drop-outs. Thereafter, the hub would slip at the slightest thing, despite all sorts on mods. In the end, I made these metal plates with the anti-rotation washer pinned to the inside via the four little holes. Torque is transfered into the frame through the rack mount and an extra small bolt. It's worked so well that I lost one of the axle nuts the other day and didn't notice!
This item has been kindly contributed by David Henshaw, editor of A to B magazine:
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9.8.2009
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General Repairs
Old Type Unit Sprocket
The motor chain drive sprocket wears rather more than the bike's sprockets due to it's small size, and the indication of excess wear is usually chain jumping over the teeth when under power. Replacements can be very expensive, but a temporary repair can be effected by reversing it on it's splined shaft. This then presents the unworn tooth faces for drive thrust onto the chain. Because the splined centre is stepped with a flange, it's not possible to replace the retaining circlip if this is done, but the sprocket is held in place by the chainline straight after the chainwheel. This might not work well with a bike converted to derailleur gears as has been done on occasion, due to the changing chainline.
See the spares page for the latest position on replacement motor sprocket supplies.
The motor chain drive sprocket wears rather more than the bike's sprockets due to it's small size, and the indication of excess wear is usually chain jumping over the teeth when under power. Replacements can be very expensive, but a temporary repair can be effected by reversing it on it's splined shaft. This then presents the unworn tooth faces for drive thrust onto the chain. Because the splined centre is stepped with a flange, it's not possible to replace the retaining circlip if this is done, but the sprocket is held in place by the chainline straight after the chainwheel. This might not work well with a bike converted to derailleur gears as has been done on occasion, due to the changing chainline.
See the spares page for the latest position on replacement motor sprocket supplies.