Making freewheel adapter solution

[mr.electric]

I have a 9c motor on my fat bike. Because of the huge tire i have major chainline issues. Until recently I have just used a 7sp freewheel with the 6 larger cogs stripped off since they were unused. The problem with this set up is that the teeth are designed to spill the chain off during shifting unlike the teeth of a single speed freewheel which are taller. In addition the hub motor side cover flexes when I pedal standing up slipping the chain or just pulling the sprocket sideways causing a grinding noise. This will eventually crack the side cover on my 9c motor. The solution , I think, is to make a tube threaded female on one side male on the other to move over the single speed freewheel. This tube would have a bearing set into the end so that the load from pedaling is transferred to the axle and does not flex the side cover. I have extra 9c bearings that fit the axle perfectly. I need two of these parts. Anyone who has cut freewheel thread before could probably make this part. I can pay ahead of time if anyone wants to take this on. I have to measure the od of the 9c side cover bearing to be set into the end of the adapter. The adapter would push out the freewheel 7/8"

 

[e-beach]

Have you every be to Tech Shop San Francisco?

My friend makes his own stuff there with the help of experts. You might like the place. Check it out.

http://techshop.ws/tssf.html

 

[mr.electric]

Good tip. I may head over there. I also considered using an online order machine shop after learning to use the provided software to model the part.

 

[mr.electric]

I figured out a spare bike parts solution. It worked as follows,
Take an extra single speed freewheel and strip off the cog. Screw on the center section of the free wheel to the hub motor. Next screw in a threaded tube that is about 1" long. This is just part of a cartridge bottom bracket you can find laying around if you have a buch of bike stuff. It is called the mounting ring or left cup. Next screw a single speed freewheel to the threads of the left cup. Finally find a bearing that fits inside the left cup and around the hub motor axle shaft and pound it in.
This set up should be strong and gives me a good chain line too.

 

[e-beach]

Nice job! How is it running?

 

[mr.electric]

Still running good. I can stand up pedaling for all I'm worth and the chain just does its job with no complaints.

 

[whereswally606]

nicely done mr electric. love the DIY off the shelf parts solution. thanks for sharing

 

[RocketRon]

Here is my freewheel done by ilia of Ebikes SF