Sprockets Sprocket on disc brake?

[barnhartmotors]

First post!

I currently have a 2-Stroke build that I enjoy on the road, but with the small tire width I think I want to get a build for trail riding.

I'm currently looking at building a Predator 79cc onto a fat bike with a CVT.

Most fat bikes have disc brakes in the rear. How would I mount this sprocket onto the rear wheel with the disc brake? Do I need any special parts?

Please give me good advice, I'm not used to 4 strokes or Fat bikes but I want to learn

Thanks for all the help!

 

[Old Busted Hotness]

While there are sprockets that bolt up to a disc brake hub, they take the place of the disc. What you would want is called a sprotor, which performs both tasks. That's what you want, but it may not be what you can actually buy; last time I looked nobody had any stock. I suspect the chain lube contaminates the disc to the point where the brake is useless, it wouldn't take much.

There's a secondary problem of spacing the sprocket or sprotor far enough from the hub for tire/chain clearance. Fat bikes use ALL the room in the frame for the tire, so spacing the sprocket out far enough may not even be possible.

You'll probably want to use a jackshaft and use the pedal chain to drive it.

 

[Member 30059]

You want what we call a russian sprocket. Its a stainless sprocket that attaches via disc holes but is offset enough to allow a 203mm disc to also be bolted on with it

Sold by this guy:
https://www.ebay.com/usr/reakwell?_trksid=p2047675.l2559

 

[Street Ryderz]

Fat tire bike's require more than normal offset to get the chain alignment correct for the output sprocket on engine and the rear wheel being much wider.The Russian guy's sprocket along with the top hat style adaptors put the sprocket out 35mm from center of the wheel hub for chain alignment to match the engine's mounted position but with fat tire bikes the engine needs to be offset more than normal for proper chain line and clearance.When using a four stroke witch requires a transmission/jack shaft the sprocket if ordering from the Russian is a custom order and back spacing should be measured on your setup to get it right as it's not the same as the 2 stroke guy's use.

 

[FurryOnTheInside]

Which fatbike frame has room in the front triangle for a 79cc Predator and a CVT?

 

[Street Ryderz]

One of my favorites,

There are very few with a bigger 4 stroke,not sure how the op intends to do it but interested!The first picture here is pretty cool second is bought not built still kinda cool neither use a cvt.

 

[Frogslayer]

Without pedals isn't it just a slow rough riding motorcycle lol? That top tube gas tank is sweet!

 

[Street Ryderz]

Without pedals isn't it just a slow rough riding motorcycle lol? That top tube gas tank is sweet!

Agreed there but just food for thought mostly,I like this one also but again no pedals and for me I'd have to register it and it's not worth it to me,still it's a cool build and again more food.LOL

 

[FurryOnTheInside]

Fatbike frames with enough room for a little 66cc two stroke are not common. One with enough room for a 79cc Predator and CVT might have to be built rather than bought.
Affordable, large, steel frames are even more rare. They only make large steel fatbikes for the kind of adventures Mr Iohan Gueorguiev goes on, so the prices are higher than the usual China fayre. Above is the only reasonably priced large steel fatbike I could find (where I am).

I would like to see one of these alloy framed fatbikes in person and see what can be done with it.

The weird forked seat tube could be a problem with a Shift Kit, I think, but then I think I see in some pictures, some of these frames don't have the forked seat tube. They use the forked seat tube to attach the standard cheap front derailleur on the 27 speed bikes.


The frame has possibly enough room for an engine and gearbox. But then does it have the strength? Its China cheap alloy bike shaped object.

 

[darwin]

I've seen it done on a mini chopper. It was neat as all get out. The caliper was used on the front of the sprocket where the chain doesn't ride. All of the bike was custom so the mounting bracket for the caliper was welded right where it needed to be. It looked like factory workmanship. 1st and only time I've ever seen a setup like that for a brake caliper using a chain sprocket for a disc.