SOMETHING BORROWED, SOMETHING BLUE
Dec 13, 2021
4 minutes
By Murray Grimwood
Photographs: Murray Grimwood
It came from a lunchtime-coffee discussion. I was noting the thrust I could put into my recumbent bicycle pedals, and the potential that had for wrecking my knees. Dad noted that at top-dead and bottom-dead centres, all our thrust is attempting to bend our bike frames; only halfway down a pedal stroke are we cyclists fully leveraged.
A moment’s pause, then, “What if we started with a right-angle pull?” Quickly he sketched a crankshaft, end on, with a big end — or a pedal — at top dead, and added a two-part linkage to one side, with a fixed pivot furthest away from the crank.
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