Motorized Bike Rear Mag Wheel Install w/ Disc Brakes

Vendedda

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Joined
Jun 16, 2020
Messages
68
I posted a few days ago that my standard bike rim walls kept forming cracks and splitting apart, and I'm now needing to buy and install my 3rd wheel in just over a year.

You guys informed me it's the brake pads chewing through the wall, and suggested I upgrade to Mag wheels with disc brakes.

So... I just got my new Mag wheel and disc brake, and I'm having a hard time finding any detailed instructions or videos online for how to convert to this new setup. Hopefully this post can be used as reference for others having the same trouble.

Now that I have the wheel, I can not see how the heck the rear sprocket is supposed to be mounted on the wheel. Supposedly the Mag wheel I purchased is made for motorized bikes, but of course, it does not come with instructions.

Do I need some sort of adapter for the sprocket?

Any help is appreciated, and I'm sure others would find the answers useful as well.
 

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Street Ryderz

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Oct 14, 2016
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4,231
Yup got the bracket already.

It's an early 2000's mountain bike. Here are some pics for reference. I'll also post an after pic, assuming install goes okay. Here is a pic of the (now pretty large) crack that formed in the wall of my rim due to the brake pads, thus the reason I hope to switch to disc. Fortunately, this is a double wall rim, so it's been holding together. Otherwise it would probably be useless by now.
You've got some issues there as Wan37 said there are no mounting brackets for disc brakes, and that frame will not allow a large enough rotor to be used and still clear the gear because the stay angles inwards too sharply. The front you could make or buy a bracket adapter.
 

Vendedda

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Joined
Jun 16, 2020
Messages
68
You've got some issues there as Wan37 said there are no mounting brackets for disc brakes, and that frame will not allow a large enough rotor to be used and still clear the gear because the stay angles inwards too sharply. The front you could make or buy a bracket adapter
Yes I'm aware this set setup may not work on my frame. I'm going to see if I can make it work, and will update the results this weekend.
 

wan37

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Joined
Oct 12, 2011
Messages
1,315
I’ve heard along time back they have bent and broke in half . So I just don’t use them. I have been on and off here since 2011. I’ve really heard and learned a lot here. Just trying to tell what I’ve heard.
 

Cisco

Active Member
Joined
Jun 9, 2021
Messages
356
I've been looking at different arched tensioner kits, and some include a couple different length shoulder bolts for the pully. A video demo showed that the idler pully can float on the bolt, but that looked like it came very close to the spokes. Also, some kits look better than others (higher quality hardware). What kit do you have?
 

Vendedda

Member
Joined
Jun 16, 2020
Messages
68
@Vendedda, I really like the chain tensioner. Is that the Navarme Arch Idler Pully Chain Tensioner? I see it on Amazon for about 30 bucks.
I love this tensioner. Just found it a few months ago, and it solved all problems I was having in that area, and can be adjusted in several different ways to fit perfectly 👍
 

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Vendedda

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Jun 16, 2020
Messages
68
I've been looking at different arched tensioner kits, and some include a couple different length shoulder bolts for the pully. A video demo showed that the idler pully can float on the bolt, but that looked like it came very close to the spokes. Also, some kits look better than others (higher quality hardware). What kit do you have?
I've been very happy with both these kits and the quality of the parts, especially for the price. As far as I can tell, more expensive kits doesn't necessarily mean better quality. Both are fast with good acceleration and torque. I weigh around 200lbs and I can pretty easily hit 35mph or faster with these. I haven't put a ton of miles on either, so time will tell how they hold up.
 

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Vendedda

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Joined
Jun 16, 2020
Messages
68
UPDATE:

So I did a preliminary install just to see how the parts I have will fit, and it's not looking good. I don't think I'll be able to do disc brakes on the rear.

The bracket I bought to mount the caliper doesn't seem to fit on my bike properly. There are other designs that might work better.

I can't see how this caliper would fit anyway, as it is too bulky to fit between the rotor and sprocket.

I do really like how the Mag looks on my bike though, and want another for the front. Maybe I can get disc brakes to work on the front wheel.

If you guys have any suggestions that might help me get disc brakes going on the rear, I would appreciate any advice. I'm going to check and see if I can find some other parts that might work better, if not, I'm going to forget about putting disc on the rear.
 

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