I am trying to put together my first bike. I ordered a 750w bafang rear hub that said it was for 175-190 dropout. My bike frame is 190mm. When I put it in the bike frame there is roughly a 7mm gap on both sides. I seen where I can get a 7mm spacer and space the rotor out and also seen 7mm wide axle spacers. I assume torque arms could fill the gap also. Problem is the wire come out of the end of the bolt and the plug is large enough I can’t slip anything on the wire or remove the current nut and bolt... what is the correct way to set this up... thank
175mm hub motor in 190mm dropout
- Thread starter Laltec
- Start date
markz
100 TW
Yeah torque arms could fill the gap, I pulled that move a few times.
ZeroEm
1 MW
Cutting the motor cable it the only way to add washers, TA, spacers. Before you do look at the chain line to see how everything will line up. TA between the motor and dropouts would take a lot of space.
ZeroEm
1 MW
You could open the motor up but it does not unplug and the wires are tight thru the axel. So first ebike I would not go there. You cut and spliced wire before right?
Oh yeah that wouldn’t be a problem … done plenty of soldering also … and have all the equipment to do that also… just something about tearing into something why it new lol. Guess I’ll just machine a couple torque arms for both side and snip the wire after my chain gets her and I can test everything .. thanks
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markz
100 TW
Yeah thats quite the gap, mine were close to begin with maybe at most 4mm space if that, so I used 1/4" flat steel plate as a torque arm to fill the gap. I think the problem I had way back then was the dropout slot was to mangled or maybe there was some inteference issues with having the t.a. normal on the outside. But I do remember have to widen the the dropout, not pinch it like what you have to do.
MadRhino
100 GW
Close the gap with torque plates inside the dropout width of the frame. That is the solid and simple solution. But, if you want washers the connectors could be pulled out of their plastic housing and likely small enough to pass through the nut.
dogman dan
1 PW
You might consider making a U shaped spacer washer, that if thick enough, can also be an effective torque arm for lower power applications. The thickness on each side, or just on one side, depending on the brake disk alignment or the rim alignment you need.
FWIW, on aluminum frames, you can just bolt it down narrower, up to about 5 mm. So two 5 mm spacers.
The U washers could be epoxied to the inside of the frame dropout, helping them stay put, with the open end facing down.
FWIW, on aluminum frames, you can just bolt it down narrower, up to about 5 mm. So two 5 mm spacers.
The U washers could be epoxied to the inside of the frame dropout, helping them stay put, with the open end facing down.
I really like the epoxying the torque arm idea without cutting the wire with just a u shape on the wire side. I will still design it to use a few small bolts as well. Suppose I will draw it up and 3D print it prior for testing before making it out of steel just to make sure there isn’t any surprises .
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