Converting a front hub motor to a rear?

[giveahoot]

Excuse me if this is a stupid question, or covered elsewhere, but is this a possiblity with added gears and a longer shaft?

 

[Ypedal]

http://endless-sphere.com/forums/viewtopic.php?f=2&t=2576

Check the pictures in that thread.

The motor side-covers can easily be replaced with " Threaded Collar " covers in order to thread on a freewheel.

However, the axle is pressed into the stator and not easily pressed out without the proper tools.....hydraulic press..

If the axle is long enough, you can replace the motor covers ( I have a pile of them if you want some ) and then thread an axle nut onto the axle as a spacer inside the frame so that the freewheel does not hit the frame..

On rear motors, the axle is milled in a way that it seats against the frame and centers the motor.. front motors do not have this.

Hope that helps.

 

[solarbbq2003]

I had some adapters made to convert front to rear, have some available if interested see pic
well wasn't the original intended use, were made to change thread on my P3 motors to fit a different cluster as thread
on some of the motors was a bit odd, but can use to change front to a rear

 

[RLT]

Good idea Solar.
That's close to what I wanted to do for my WE BD36 hub, but was too lazy and not sure enough of my lathe skills.
If I'd known you had something like that, I'd have bought one from you.

I ended up just bolting a fixed sprocket to the motor cover and using a freewheel on the pedals. Pretty easy to do it that way, although only having a single speed, and the chain always running is less than ideal.

I'll post some photos of it when i get a chance... I thought I had some on this computer, but apparently I don't.

 

[Link]

I wanted to do that to a BD36 too, but I don't have a lathe at all :?.

 

[RLT]

If you meant to put a single fixed sprocket on, you don't need a lathe.

I did use my lathe, but only for layout, to make sure that I had the sprocket bolt holes on a concentric circle.
With careful measuring, all you really need are a drill, a drill bit, the sprocket, sprocket bolts , ~3mm wide bolt spacer rings..... And of course, the freewheel cranks from Cyclone (or more expensive BMX ones) and a freewheel /sprocket to put on them.

The hardest part was getting the motor side plate off.

 

[Link]

O rly?

Hmm, considering that the motor's eventual home will be on a BMX, I think I may yet get to keep the pedals .

 

[RLT]

I finally found the photos of the fixed sprocket to hub motor plate modification. Pretty simple, if less than ideal solution to convert a front hub motor to rear drive. This was on a Wilderness Energy BD36... I assume the process would be the same on just about any brand of hub motor. Of course you need a chainring freewheel for this to work safely.

I'd rather have adapted a freewheel to the motor and left the chainring as is, but this was the easiest , cheapest way to do it.

Trickiest part is getting the layout concentric and drilling the holes accurately.
Hardest part is just getting the side plate off the motor if you don't have a big gear puller. Took me longer to get it off than to do the whole rest of the modification,
plus I kind of mangled my axle a bit in the process (I'm ready for next time though thanks to a good sale at Harbor Freight.).

Got the sprocket and the sprocket bolts from the same Ebay seller for about $10....









I made my own spacers by cutting off pieces of an expansion bolt sleeve that I happened to have laying around that had the right I.D. Easier to buy them of course... I just didn't know in advance I was going to need them, so rather than wait for an order, I used the field expedient.

Will try to get some photos of the freewheel pedal setup and how the whole system works in a few days.

 

[Link]

That's a pretty big chainring. What are you running on the pedals?

 

[RLT]

Thats a 24, Running a 28 on the cranks. I wanted to run a 32 or 36 up front, but they were sold out., so I had to make due by cannibalizing from what I had laying around that would fit.

It works out to about the same gearing I use on a regular bike to climb the steep hills around here, and since I don't plan to do much pedaling if I can avoid it, it should do.
Heck, The main reason I have pedals on this at all is to keep it (sorta) legal under the eBike law. (As long as I can get them to believe that both motors are only 350 watts each, I ought to be OK if I ever get stopped. )

 

[fechter]

If you had a freewheeling front crank it would solve the problem, but those tend to be somewhat expensive. That setup might be useful in a bottom bracket drive.

 

[RLT]

I do have a front freewheel crank. The Cyclone ones are reasonably priced:
http://www.cyclone-usa.com/store.php?crn=203

 

[lawsonuw]

I wanted to do that to a BD36 too, but I don't have a lathe at all :?.

This mod could likely be done with a spacer ring that fits between the cover's short bearing boss and the inside of the sprocket. And a set of transfer-punches to get a good starting dimple for a drill and drill press. If someone finds a roll of tape with an internal diameter that matches the cover's bearing boss outer diameter you'd be good to go.

Marty

 

[Mad_Q]

I had some adapters made to convert front to rear, have some available if interested see pic
well wasn't the original intended use, were made to change thread on my P3 motors to fit a different cluster as thread
on some of the motors was a bit odd, but can use to change front to a rear

do you still have this adapter available?

 

[Chalo]

What's so bad about using a front motor in the front, compared to ruining your stuff and inventing new cuss words?

 

[Mad_Q]

What's so bad about using a front motor in the front, compared to ruining your stuff and inventing new cuss words?

trust me, im tempted to keep it simple but this is for a fat tire bike a sidecar attached for my daughter and i live in the desert, dirt / sand roads... im very afraid a front hub wont have traction to pull us... so i have two options, buy a kit and have it relaced into my wheel or find a fat tire kit, cant find an affordable rear one...

 

[Chalo]

What's so bad about using a front motor in the front, compared to ruining your stuff and inventing new cuss words?

trust me, im tempted to keep it simple but this is for a fat tire bike a sidecar attached for my daughter and i live in the desert, dirt / sand roads... im very afraid a front hub wont have traction to pull us... so i have two options, buy a kit and have it relaced into my wheel or find a fat tire kit, cant find an affordable rear one...

You have a better option. Try an Xtracycle Free Radical or the like instead of a sidecar. That puts your body weight much more over the front wheel for traction, and allows you to pass through bike path bollards and other restrictions. It's probably cheaper and more capable than what you're talking about, too.

Xtracycle has a new, more badasser frame extender in the works, but it will be a little while before you can buy one.

 

[Mad_Q]

What's so bad about using a front motor in the front, compared to ruining your stuff and inventing new cuss words?

trust me, im tempted to keep it simple but this is for a fat tire bike a sidecar attached for my daughter and i live in the desert, dirt / sand roads... im very afraid a front hub wont have traction to pull us... so i have two options, buy a kit and have it relaced into my wheel or find a fat tire kit, cant find an affordable rear one...

You have a better option. Try an Xtracycle Free Radical or the like instead of a sidecar. That puts your body weight much more over the front wheel for traction, and allows you to pass through bike path bollards and other restrictions. It's probably cheaper and more capable than what you're talking about, too.

Xtracycle has a new, more badasser frame extender in the works, but it will be a little while before you can buy one.

here's what i have:

https://www.youtube.com/watch?v=kMeGysReVbg

 

[Chalo]

If you're using one of those, and pulling your kid, you have no business using more torque than you can stick to the ground through the front wheel.

 

[dogman dan]

Machining a new axle for a motor will just cost more than getting a rear motor, with an axle long enough for your fat bike.

You may not need new everything, just a new motor.

 

[Roginator4000]

I had some adapters made to convert front to rear, have some available if interested see pic
well wasn't the original intended use, were made to change thread on my P3 motors to fit a different cluster as thread
on some of the motors was a bit odd, but can use to change front to a rear

@solarbbq2003, longshot since you posted in 2008, but do you have any of these left? Or has anyone else seen something similar? My wife has a 1970's bike with 110mm rear dropouts.

 

[amberwolf]

some other threads on the topic
https://endless-sphere.com/forums/search.php?keywords=convert*+front+rear&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

including how to diy it:
https://www.endless-sphere.com/forums/viewtopic.php?p=551146#p551146

 

[Roginator4000]

Amazing. Thanks. I was thinking of cutting a hub! Glad to see it's worked!