Mag Wheel Hack

[Cannonball3]

Being economically challenged these day finding the extra $$$ to have my bike specific rear mag machined or buying a new set forced
some out of the box thinking. The existing mags hub extends to the brake disc allowing no sprocket alignment. This is what I came up with.
I know about the offset loading, and thats less than ideal, but you never know til you try. Disregard the hardware its just holding the concept together,. The actual chain line will be very close to the small sprocket and a 203mm disc will bolt on the other side. Will increase the primary sprocket hardware to 1/4” gr8.

 

[Cannonball3]

Also wound up with a disc brake spacer for future use.

 

[Chainlube]

Nice, two speeds.

 

[DieselTech]

Being economically challenged these day finding the extra $$$ to have my bike specific rear mag machined or buying a new set forced
some out of the box thinking. The existing mags hub extends to the brake disc allowing no sprocket alignment. This is what I came up with.
I know about the offset loading, and thats less than ideal, but you never know til you try. Disregard the hardware its just holding the concept together,. The actual chain line will be very close to the small sprocket and a 203mm disc will bolt on the other side. Will increase the primary sprocket hardware to 1/4” gr8.

My grubee hd rear spoked wheel is setup like that on my 4 stroke bike, soo far I havent had a issue & got probably close to 800 miles or more on it.

 

[Cannonball3]

Thanks for the comments yall.
Chainlube its not a two speed, would be cool if it was. The first sprocket is just a mount for the second sprocket and the brake disc. Ideally about a 1/2”+ would need to be machined from the disc mounting surface to establish the chain line. The chain line is the second sprocket. The disc mounts directly to the first sprocket. Spacers between the first and second sprocket adjust the chain line. I have in the past had to stack two sprockets outward to get alignment. This is going the other direction. Saves about $100 in machine work that I was quoted.

 

[Chainlube]

Thanks for the comments yall.
Chainlube its not a two speed, would be cool if it was. The first sprocket is just a mount for the second sprocket and the brake disc. Ideally about a 1/2”+ would need to be machined from the disc mounting surface to establish the chain line. The chain line is the second sprocket. The disc mounts directly to the first sprocket. Spacers between the first and second sprocket adjust the chain line. I have in the past had to stack two sprockets outward to get alignment. This is going the other direction. Saves about $100 in machine work that I was quoted.

I know what you're doing, but two speeds would be nice.

Have you ever saw those mini-bike disc brakes that use the rear sprocket as the disc?

 

[Cannonball3]

No but I have seen M/Cs that do. That would solve a lot of issues. There is probably a M/C caliper that is deep enough and wide enough to maybe span the chain. Surely for a 35 chain, maybe a 41?.

 

[Cannonball3]

Here is the final stack up. Had to center cut a 38t. The hardware is NOT final , just holding it together. Also the disc is only a 180, as any one building a rear disc set up knows takes a 203 and a bunch of patience to set the clearances. The CDH frame I am running has very limited clearance around the disc brake mount to compound the problem. Skewer axle going solid.

 

[Cannonball3]

Heres a pic of the secondary sprocket In case there is confusion for some folks about what I am doing here, my wife says I assume a lot, Im a guy right.

 

[Risk Man]

Heres a pic of the secondary sprocket In case there is confusion for some folks about what I am doing here, my wife says I assume a lot, Im a guy right.

This is my CDH mag wheel with the stock hub, typical spacer after the sprocket and then the disc. Was a bit tricky to light up (axle length and spacers on axle) but it worked fine with stock components. This is the latest (but certainly not "greatest") BS berry motor ready bike (Which it was not motor ready, and I replaced the wheels with these)