Are there any kits that fit a 110mm rear hub drop out?

[Bumtreq]

Hi guys,

I decided to keep my Raleigh Twenty as is and work on my 24” bmx. I’ve looked at mid engine builds with the same bike; but it looks like a nightmare for chain alignment and quite a bit of grinding to make it fit. Decided I’d opt for a rear hub kit.

The problem I’m having now is finding a kit that will fit a 110mm drop out? Do they exist? Am I going to have to try and manually bend it to 135mm?

Here’s the bike:

http://imgur.com/a/OHk4JI2

Cheers
B

 

[Bumtreq]

I’m thinking of manually widening the drop outs to 135 as per this YouTube video. I suppose this will mess with the chain alignment?

 

[Nealh]

Rear hub motors are 135mm or 142mm for ones like the Xiongda.

 

[Jonah]

Rear hub motors are 135mm or 142mm for ones like the Xiongda.

The Aikema 85SX is listed as 100mm, not sure if that’s the same measure since it was a snug fit in my 140mm dropouts.

 

[Woosh]

Aikema 85SX: 100mm is the motor casing diameter, dropout 135mm.

 

[Kwozzymodo]

Have you thought about a front-hub conversion?

 

[Bumtreq]

I’ve looked at front hub, but haven’t heard great things. I might give a 135mm kit a shot, widen the rear dropouts 12.5mm each side. They aren’t super expensive on alibaba, so if it doesn’t work out, I’ll go a front hub.

The sellers are recommending a 48v 13ah hailong battery. Any good? I need to travel about 9miles round trip, but I’m a heavy rider.

 

[Sturmey]

I’ve looked at front hub, but haven’t heard great things. I might give a 135mm kit a shot, widen the rear dropouts 12.5mm each side. They aren’t super expensive on alibaba, so if it doesn’t work out, I’ll go a front hub.

The sellers are recommending a 48v 13ah hailong battery. Any good? I need to travel about 9miles round trip, but I’m a heavy rider.

You wont be fitting a rear disc or a wide freewheel, so its may be possible to fit the torque anti-rotation washers on outside of dropouts (with the tab facing inwards) instead of inside., saving about 8mm of width. Depending on the kit and your dropouts , it may be also possible to save another few mm.
But, one thing I would be concerned about is the frequent need to open axle nuts to adjust the chain. And of course, you will need to get the chainline right.

 

[Kwozzymodo]

12.5mm on each side of the frame is a substantial movement. Is the fame up to it?

 

[Bumtreq]

12.5mm on each side of the frame is a substantial movement. Is the fame up to it?

Not sure. Don’t see any other option at the moment. I’ll play around with the kit to see if I can make room. I only need one sprocket, so maybe I can make it work with less movement.

 

[Sturmey]

....maybe I can make it work with less movement.

Sheldon Brown has a useful article below. I am assuming you have a steel frame. Watch out for cracks forming where the two seat stays are bridged and similarly at chainstays. Some chainstays have a weak spot at dimple behind chainwheel. Some recommend clamping at weak spots. (point 3 in article),
The 2X4 method allows individual adjustment of each side (which may be useful), as threaded bar can push out one (weakest) side more. Some motor kit have axle threaded further inwards so you might get away with 120 -125 mm spacing when fitting torque washers on outside. You may have to reduce the wheel dish (adjust spokes).
There is a few tricks that can be done to get chainline right.

Bicycle Frame/Hub Spacing

A bicycle frame and fork should match the wheels that are to be used in it. Older bicycles used narrower spacing, but older frames can often be spread out to match more modern wheels.

www.sheldonbrown.com

 

[Bumtreq]

Sheldon Brown has a useful article below. I am assuming you have a steel frame. Watch out for cracks forming where the two seat stays are bridged and similarly at chainstays. Some chainstays have a weak spot at dimple behind chainwheel. Some recommend clamping at weak spots. (point 3 in article),
The 2X4 method allows individual adjustment of each side (which may be useful), as threaded bar can push out one (weakest) side more. Some motor kit have axle threaded further inwards so you might get away with 120 -125 mm spacing when fitting torque washers on outside. You may have to reduce the wheel dish (adjust spokes).
There is a few tricks that can be done to get chainline right.

Bicycle Frame/Hub Spacing

A bicycle frame and fork should match the wheels that are to be used in it. Older bicycles used narrower spacing, but older frames can often be spread out to match more modern wheels.

www.sheldonbrown.com

This is really helpful. Thank you.

 

[Bumtreq]

Can anyone recommend a torque arm set that might work with a bmx? All the ones I’ve seen appear to require a second fixing that the bmx doesn’t have...

 

[Sturmey]

Can anyone recommend a torque arm set that might work with a bmx? All the ones I’ve seen appear to require a second fixing that the bmx doesn’t have...

Do you need torque arms? The 250/350W kits normally come with 2 special washers that both grip the axle and grip the frame. I have fitted a rear hub to a horizontal steel frame and found it easier than alloy frame as dropout slot was long and no need to file, except to clean some of paint off to get the 10mm. Its better if wheel is pushed well up into slot. As chain wears, its necessary to move wheel back. This could be a disadvantage but it is possible to fit a chain tensioner.