Sprockets Sprocket on disc brake rotor hub axle thing

lukecanna

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Sep 25, 2017
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Melbourne, Australia
Hi,
So on my most recent build the real wheel had a disc brake so once I took it off I was able to drill some holes through my sprocket and mount the sprocket directly to the old rotor hub. even used the old rotor mounting hardware, seemed alright
this was much easier and I was 100% sure my sprocket was straight.
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Offset.
As gary55 already showed, the sprocket needs to be a bit inboard of the rotor mount, even on single speed 110mm OLD hubs, to get it lined up directly behind the engine sprocket. On a 135mm multi speed hub like mine (and yours?) the offset is considerably more.
Although I have been experimenting with a nine speed chain that is more flexible (requiring narrow sprockets), having perfect or very nearly perfect alignment makes it much easier to keep the chain on and running smoothly and efficiently!
You do not want to experience the chain coming off and slipping between rear sprocket and your spokes when you are riding at speed!
 
View media item 61331
View media item 61334
Offset.
As gary55 already showed, the sprocket needs to be a bit inboard of the rotor mount, even on single speed 110mm OLD hubs, to get it lined up directly behind the engine sprocket. On a 135mm multi speed hub like mine (and yours?) the offset is considerably more.
Although I have been experimenting with a nine speed chain that is more flexible (requiring narrow sprockets), having perfect or very nearly perfect alignment makes it much easier to keep the chain on and running smoothly and efficiently!
You do not want to experience the chain coming off and slipping between rear sprocket and your spokes when you are riding at speed!
Thanks furry, I like your stack but the issue with mine is it is a stupid quick release and moving it around anymore will cause issues with the frame
 
@gary55 what the hell man, making me blush over here haha! It's a nice sprocket stack but jeesh, too much! :seenoevil:
I have to say, we all made the Night Fur(r)y. All the forum members and the love of bikes we all share is the reason for every bit of everything I have ever achieved in this hobby! I would not have been able to build any motorised bike at all without the help of everyone in our forum community who selflessly contributed their skills and experience to the forum, writing posts and helping each other out over the last ten years! :giggle:

@lukecanna can you explain more please, help me understand what exactly is the problem with your QR and frame? Your hub looks pretty identical to mine from the picture. :unsure: I am not suggesting that you need a sprocket stack, only that, by some means, the sprocket needs to be well inboard of where the rotor would be/ where the outer adapter plate (spider) is on my hub.
I am expecting you will find that the chain runs very smoothly and is easy to control if the sprocket is close to the spokes, at least half an inch but probably 17.5mm inboard (right) of where it is now, about where my second largest sprocket is. That's similar to where the rag joint doughnut from the kit would have positioned it.
Edit, I forgot the sprocket is dished, and I don't recall exactly what the dish is, so I'm guessing that the magic number would be like 16mm or 17mm if you flip the sprocket over. You must measure everything to be sure of the best offset for your bike. :geek:

There are always many times we have to backtrack when building something novel but we must not be discouraged. New ideas aren't that straightforward but everything is possible with a little help from the forum community. :giggle:
I am sure that any issues can be solved. We can build anything! :LOL:
 
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This is what happens when someone seriously knows their sh*t about bikes and then motorizes one. Mechanical art work.
Damn right!
I look for certain people to respond to certain questions and he is (one of) the bike guy(s).
 
Aw, man. All the love in here :cry:

Oh yeah and don't forget to subtract the thickness of the sprocket from that 17.5mm (or whatever you find is best after checking the dimensions) as well as accounting for any sprocket dish.

There is an adapter in various offsets (MBRebel?) but I think that only fits the sprockets they make with the right hole pattern (meaning that idk if you can drill out new holes for it, much depends on whether those would need to overlap the present holes I think).
So it would cost quite a bit more than the way gary55 showed using two of the kit sprockets and some nuts n bolts. I like his method very much indeed. I think the use of a drilled ring instead of separate spacers for each bolt might add some extra rigidity to that when used to span a larger offset that you'll need for a 135mm OLD hub. :)
 
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