e-kit Install - Centering my new wheel with hub motor

[scooter2012]

I have an Ice Trice with 20" wheels and 140mm drop outs (ICE told me that the space is 135 but I think it measures 140mm). I have purchased a BMC 4T which has been built onto a new 20" rear wheel. I took off my old wheel and installed the new one but find the wheel is quite off-center. The freewheel side is 1/2 inches closer to the forks than the other side. It's an aluminum frame so adding a bunch of spacers to increase the distance between the wheel and frame on that side is out.

It looks like the hub motor casing has a stub on the non-freewqheel side that sticks out about 1/2 inch which creates the extra space between the wheel and true frame on that side. I don't think that it would be possible to cut it.
Any ideas? Thanks!!

 

[Drunkskunk]

pics of the problem would belp, but it sounds like you're describing a normal motor to me. The motor its self won't sit centered, there is more room on one side for gears, as with any external geared rear hub, motored or not.

Do you mean the tire isn't centered in the frame? If thats the case, its a matter of truing the spokes to align the tire to the bike frame's center.

 

[scooter2012]

It's the wheel/tire that is off center. It's 3/4" away from the frame on the non-freewheel side and 1/4 on the freewheel side.

 

[Drunkskunk]

That is cured by loosening the spokes on the freewheel side, and tightening them up on the disk brake side. Do you know how to true a wheel?

 

[scooter2012]

It's a new wheel, made for a bmc v4 hub motor. Does truing a wheel really change the wheel location a 1/2"? It's only 20" and the hub motor takes up about 8".

 

[rkosiorek]

most certainly you can better center your wheel by adjusting the spokes. for 1/2" though you may need shorter spokes on one side and longer ones on the other.

rear wheels are often built off center of the hub in order to be centered in the frame. this is referred to as "DISH". and to make life even more exciting on many bikes, especially those for 8 or 9 speed hubs the frame is off center to make room for the wide gear cluster. so if i build a wheel that is centered on it's axle flats it will most certainly look to be off center in the frame. and to make life harder, there is no accepted standard for how large this offset is. it is different for 3spd, 5spd, 7sp and 8,9spd bikes.

so yes, it is very normal for that nice new supposed to be perfect rear wheel, not to fit perfectly centered in your bike frame. either accept it and work to adjust the fit for your particular bike, or do your best to get a refund. you would be disappointed with an exchange. it likely will look just as bad as what you already have.

rick

 

[scooter2012]

Thank you for your thoughtful reply. We decided we could live with the off centered situation so we put it on and tried to go through the gears. All ok except in low gear the derailleur bumps up against the tire and spokes. maybe adjusting the screw will solve that.
Lynn

 

[d8veh]

I've had to dish every motor wheel tha I've installes.Some wew a long way off centre.

Get yourself a spoke key. Start at the valve and loosen the nipples 1/2 turn as you go round one side and then go round again tightening the nipples 1/2 turn on the other side. You'll probably have to go round three or 4 times. The rim normally stays pretty true, but you might have to adjust a little afterwards or get a bike shop to do the final truing if you're not sure how.

 

[John in CR]

Lynn,
You want the wheel centered for optimum handling. Changing the amount of "dish" is common because as Rick said the Chinaman who laced the wheel doesn't know what bike you have. It's a simple matter that you need to learn now or have to pay someone to do it very soon, because it's typical that the spokes will need attention in the first 100 miles or so anyway. Changing the amount of dish is even easier than truing the wheel, because you simply loosen the spokes going to the flange on the motor on the side you want to move the tire away from all by say 1/2 turn, and you tighten the spokes going to the motor flange on the side you want to draw the wheel toward all by the same amount. The valve stem is a good marker as a start and finish point.

It's easy. Don't be afraid to try. Learning this kind of new stuff really gives you ownership of your vehicle and an increased sense of independence for your transportation.

Note that the Sheldon Brown website is a great resource for everything bike related, pedal bikes, not electrics.

Welcome to the revolution!

John

 

[dogman dan]

Loosen spokes a turn on one side and tighten a turn on the other to get some dish going to help. 1/2 is a lot, and might require different length spokes to get it all with dishing.

If you have enough axle length, then use some spacer washers to get the tire centered. Then make deraliur adjustments to get your gears to work right.

 

[shock]

My ebike geared kit dishing was seriously off center like this also, and I ended up removing all the spokes on one flange and reinstalling them in the opposite side of the flange in order to dish the wheel out to center. In the end all of the spoke ends pointed the same way, hope this makes sense. Below is a simple diagram of how the spokes looked in cross section.

Normal

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Redux

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