mid-drive physical specs?

red

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Hello, I am new to ebikes; got a million questions. I am in the USA. Dollars count here, so I am thinking I might build up a thrift-store bike. I would like a mid-drive set-up with freewheel. I can see the mid-drive will replace the usual pedal crank. After the pedal crank is gone, I will be left with an empty hole in the frame. These frame openings will be different sizes on different bikes. How wide (long) should that frame tube be (between the pedals), where the mid-drive fits? What inside diameter should this frame tube be? By what names do you call these frame dimensions? Will the mid-drive use any threads now in the frame tube, or does it mount with adapters? I would guess that some mid-drive kits will fit more stray bikes than others, so any recommendations? TIA.
 

HumanPerson

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68-73mm width for a normal bike.
73-100mm width for fat tire bikes.
120mm extra fat bikes.

Now you might not want to do a bbshd install but here is a vid of an instasll of one:


Most times the motors spindle will just slide right into the bicycles bottom bracket, other times there are some things needed but i have not encountered that as of yet.

BBSHD mid drives are pretty bullet proof but they are cadence sensors not torque sensors so they have a ramp up and ramp down,
as where the torque sensor motors dont ramp down as the cadence sensor motors do.

Welcome to our humble home by the way, red :cool:
 

red

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HumanPerson,

Thanks for the specs, that will be helpful. I'm guessing that pedal shaft is thin enough to fit through most frame tubes. The install seems easy enough, but those special tools will be needed. I should get them anyway, so no problem there.

I would hope to have two chainrings at the front, though. This place is high desert; we just had 30+ days of 100 degrees F (38 degrees C) this summer. It would be easy to overheat any motor here.
Thanks again.
 
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