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Old 01-14-06, 07:27 PM
  #13  
geebee
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Join Date: Mar 2004
Location: Tasmania, Australia
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Bikes: GT3 trike,Viper chopper, electric assist Viper chopper,Electric moped(Vespa style)

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Hub motors are an elegant solution but they have some limitations. The hub locks you to a single or 2 speed (second winding in the hub) which means low torque at low speeds with direct drive and a predetermined top speed commensurate with enough torque to get moving.
A geared hub sacrifices top end for sheer grunt on hills and takeoff, a motor driving at the bottom bracket or even just using the rear sprockets would allow use of the bikes gear train so heaps of power for climbing and good assist at high speeds.
I have a few hubs, and really steep hills and off road mountain trails show the short comings of the hubs pretty rapidly. I have seen a few outrunner style motors on ebay with highish wattages and relatively low rpm around 900 rpm which would reduce gearing requirements dramatically.
I have concerns about these motors longevity in prolonged operation ie. an hour or 2 continuously everyday, I have 1 hub with thousands of klm on it an it still runs as new.
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