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Jeff's Electric Moped
Jeff Caswell showed his electric assist utility bike for anyone who hadn't already seen it. It is a converted cheapo MTB that weighs a svelte 71 pounds, though he swears it handles nicely with the added weight so low and centered. The motor has an amazingly small Sprague clutch (that many people didn't even notice at first glance) on the end of its shaft so the motor can freewheel when not in use. The advantage of this was readily apparent from the extremely notchy and draggy action when he rolled the bike backwards. Mark wondered if two such clutches could be used as a pseudo-differential on the rear axle of a delta trike. Probably, but some people had concerns about the torque rating of a Sprague clutch, especially in such a small size. Jeff uses a 600 Watt Currie motor, and he modified its usual mounting plate so it would fit on a bottom bracket and be held in place by the BB locking ring. His setup is quieter than a stock Currie drive, probably because it dispenses with their planetary reduction gears, using two very different sized sprockets instead. His headlight is a $10 LED "cabinet light" from Menards that seems to work well and is way cheaper than the typical purpose-built bike light system.
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