Bicycle crank modification

Henry, a pensioner, is a keen cyclist who will ride 50 – 60 miles in a day. Years ago, a motorcycle accident left his right leg and ankle deformed. His ankle is out of line with the centre of his foot and so the inner side of his anklebone tends to contact the bicycle crank arm on each revolution of the pedals resulting in pain by the end of a ride.

The engineer made an extension piece in aluminium alloy with an M22 external thread at one end and an internal pedal spindle thread through it. The crank arm internal thread was then enlarged to M22 so the extension piece could be screwed into it and secured with engineering adhesive. The pedal spindle screwed in as normal. Care had to be exercised to ensure that the new threads were true to the original axis.

Henry is absolutely delighted with the modification and is now able to ride long distances without the pain of his right ankle constantly striking the bicycle crank arm.