Type of chain vrs 750 watts of power ? [Archive] - Bike Forums
EbikeHawaii07-
This is for those who spend the time to make a lighter more efficient system than you can get from any hub motor.First of all on mid drive systems it does not make any sense to gear down a motor to drive bicycle chain to match the pedal cadence to drive through a bike chain and a clunky derailer using a 750 watt motor.With less reduction (about 8 to 1 for a 26" wheel) you would be best off using a 219 or 8mm gocart chain and composite sprockets from 72 to 92 teeth that cost as little as $8. each if you look around.Of course you will need a strong low 2000 rpm torque motor above 1 hp or 750 watts of power to eliminate power robbing multigear reductions that all mid drives on the market offer..Multigeard hubs have a great efficiency because the ratio is low and they spin fairly slow.Not so with 3000 rpm motor reducers.These sprockets and 8mm chain are the most efficient chain/sprocket arrangement you can get for up to 25 HP and 12,000 rpm.
At 750 watts they are much more efficient than bike chain or #25 chain and the 8mm chain won't stretch at all.For 4 years I have only used this arrangemet on my ebikes...You can adjust sprocket ratios rather easily compared to buying another hub motor.
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219 Sprockets are 40% lighter than anything on the market today. Made of Kevlar, these sprockets are stronger, quieter, more durable, and feature less sliding resistance (keeping the sprocket cooler, thereby increasing chain life) than either aluminum or steel sprockets. Specifically made for karts using 219 chain and 6-bolt carriers.