Best way to secure hub-mounted sprocket?

Discussion in 'General Questions' started by Engineer, Jun 28, 2015.

  1. Engineer

    Engineer New Member

    As you all may already know, the installation for hub-mounted sprockets is pretty straightforward. But seeing as the surfaces of the hub itself and adapter are smooth, I don't see them able to adhere to one another securely, even with substantial tightening. Therefore I'm trying to figure out the best way to secure the sprocket so there isn't any possible slippage between the adapter and hub (or axle) caused from the torque of the motor.

    Since I haven't found much of anything relating to the thesis of this topic through loose research I figure we could all come up with some sort of solution to eliminate the chance of slipping over time.

    Brainstorming / R&D:

    - Metal shim(s)
    - Strip of innertube rubber between hub and adapter to increase grip
    - Scoring the metal of hub and adapter (without ruining the integrity of either)

    What I've listed are just ideas, not suggestions or sure-fire solutions. If you creative lot have tried anything that's worked exceptionally or have thought up a method you think is useful, feel free to share. :D
    Last edited: Jun 28, 2015

  2. Engineer

    Engineer New Member

    I've tried the strip of innertube rubber, it worked only to an extent. After a couple dozen miles it began to tear and somehow slipped from underneath the hub adapter. In conclusion, it failed.
  3. butre

    butre Well-Known Member

    just crank down hard on it, you'll wreck your tool before you damage the threads. I've got around 1500 miles on my hub adapter without failure
  4. The_Aleman

    The_Aleman Active Member

    The clamping force of the adapter is plenty enough to keep it in place, as long as it's the right size for the hub and you've tightened it enough, as butre said.

    Using any kind of shim is unnecessary (and not recommended) and you do not need to score the mating surfaces.
  5. crassius

    crassius Well-Known Member

    green loctite will probably hold it if you never need to take it off again
  6. butre

    butre Well-Known Member

    loctite isn't glue, it only works to fill the space between the threads and provide resistance.
  7. crassius

    crassius Well-Known Member

    don't know if it has changed, but in the 60s I knew an old mechanic that put crank cheeks back together with green & they were close to welded
  8. bikejock

    bikejock Member

    I sandwiched my sprocket so the sprocket is in the middle of the rubber clamps & the hub is through the hole. I had to bend my brake arm further but now I know my sprocket is on perfectly. I also got some lock nuts & better quality bolts because I don't trust using cheap bolts with all metal lock nuts.
    Here's how it looks:


    I had to get creative to make the coaster brake arm fit back on the frame with a bracket I found & some bolts.
    Last edited: Jun 29, 2015
  9. crassius

    crassius Well-Known Member

    Did you use three rubbers? Metal on spokes usually cuts them pretty quickly.
  10. KCvale

    KCvale Motorized Bicycle Vendor

    This topic is about securing a specialty clamshell hub sprocket adapter directly to the hub, not the 'rag joint' sprocket.

    I do however need to point out that this is an example of how NOT to install a kit sprocket.

    The sprocket itself is one side of the mount, nothing goes on the outside of the sprocket.
    Those 'rags' which are actually circles cut out of recycled tire sidewalls, are meant to sandwich your spokes and hold them.
    The metal plates are used to form a circle around the inside 'rag' for the bolts to go through from the sprocket and secure the whole sandwich together.


    By tightening the 9 bolts in a star pattern you bring the outside metal parts together and the rubber forms itself around the spokes.
    I find this a better method if done right that any clamshell hub, it doesn't have grip the hub directly and does provide a bit of 'shock isolation' between the engine and back wheel.

    In short bikejock, having a set a metal rings and a rubber rag joint on the outside of the sprocket does nothing good, the sprocket itself is already one side of the sandwich to begin with.

    Having your sprocket right up against your spokes and only one rag inside will cause your sprocket to not stay true which in turn is going to cause metal to metal wear on your spokes with the wobble, and of course eventual failure.

    If a dust cover is in your way, toss it, just oil that spot regularly.
    If the brake arm don't clear the bolt heads bend it, I find a vice and a big crescent wrench works well for this.

    Not trying to 'rag' on you bikejock, you are a good guy, but that is not a sprocket mount to be proud of bud hehe ;-}
  11. bikejock

    bikejock Member

    Sorry KC, guess I misunderstood the thread.

    Anyways my rear sprocket setup works pretty well. It is plenty secure. Put 17 miles on her & no problems. I had to go down a tire size because that 3 wide was too big for what I wanted to do originally. So now I have a Kenda 24x2.125 in the rear. Looks kinda weird because it has a 26 front wheel.

    I have my sprocket mounted that way because it was difficult getting it to allign right. I was thinking of upgrading to a heavier duty rear sprocket but my set up works just fine for now.
  12. KCvale

    KCvale Motorized Bicycle Vendor

    Heck, ALL of us do that at times bud, no worries ;-}

    Just a Tip...
    When it starts throwing drive chain keep the above tips in mind when you remount the sprocket to hopefully still good spokes.
  13. bikejock

    bikejock Member

    I'm thinking of maybe putting some kind of thin rubber or maybe leather buffer between the sprocket & spokes to prevent wear from as you stated "metal to metal wear." KC, what thoughts on this? My hub wasn't able to reach the hole in the sprocket the traditional way so I'm hoping to use this method because this way I know my sprocket is aligned properly. My spokes are pretty sturdy so I don't see them failing anytime soon. It's actualy a pretty well built bicycle wheel.

    Also, what kind of upgraded sprockets would you recommend? I would like to do away with the stock stuff like the rubber clamps & sprocket.
  14. KCvale

    KCvale Motorized Bicycle Vendor

    The main question is why your sprocket cant get to the hub, like a dust cover or the sprockets hole being tot small but that's ok, it doesn't have to.
    Cup the teeth in.

    The first best step is make sure your sprocket is true to begin with.

    I wasted countless hours when I first started trying to true a non-true sprocket.
    You can't hehe ;-}
    Lay the sprocket cupped down on a dead flat surface and see if it has ANY wobble.
    If it does it will never be right, and even good kits occasionally have one, but a quick glance at the shelf I keep mine on I say I have 20 warped ones.

    As for alternated solution sprockets like clam-shell type mount I have no opinion, never needed to use one so I can't help ya there.
  15. jatgm1

    jatgm1 Member

    ive had my three point manic mechanic clamshell sprocket adapter on for a while, make sure that the points are back in their respective hole through the spokes so that when you hit the gas your not pressing the point against a spoke. and clean off the hub and the adapter THOUROUGHLY with brake cleaner before installation. if you want for good measure lightly use some emery paper to give it some scratches so they can grip eachother. if you tighten it well you will be fine, but the two bolts need to be tightened evenly. so far ive had lots of issues, but after using a manic mechanic adapter, the wheel was never one of them again. other than the tire and tube, but thats just due to thorns. those rag tag adapters that come with the kit are complete garbage. my spokes basically became bent beyond what was safe in a matter of no time, it was like under 20 miles before it was bent to a dangerous degree.