Sprockets Rear Sprocket Hub Questions

Discussion in 'Transmission / Drivetrain' started by Anhevius, Aug 4, 2014.

  1. Anhevius

    Anhevius New Member

    I am looking at running an HT motor for my first build. (I don't want to get too deep into costs before I've got a good grounding in this.)

    One of the things I am leery of is the sprocket clamshelled onto the spokes. That just screams cheap and dangerous to me.

    I have seen several hubs with mounting for sprockets, but they're all showing for four-cycle engines (freewheel design). Is there a good option for the HT engines out there? I've found one so far through a link on this forum, though that's the only place I've seen it mentioned. Has anyone used it?


    I freely admit that this is all new to me. I'm used to working on vehicles, primarily older ones.

  2. butre

    butre Well-Known Member

    check out either the sickbikeparts shift kit or a manic mechanic sprocket adapter. you're right about the rag joint mount being cheap and dangerous.
  3. Anhevius

    Anhevius New Member

    I'm looking at the sickbikeparts shift kit...and I'm lost.

    What it LOOKS like from the pictures is that it's designed for a bike with a single front sprocket and a rear only shifting system.

    Or does it fully eliminate the front shifting assembly to replace it with the single sprocket? The 'manual' and product description are rather vague.
  4. crassius

    crassius Well-Known Member

    I've always and only used the rag joint. After the first 3 or 4 to get used to how they work, I've never again had any problems with them.
  5. Anhevius

    Anhevius New Member

    Unfortunately, I am not sure that I will have the time or resources to get used to the rag joint, since I am planning on running a business utilizing the MB. I think for a first build, the wheel I linked is a good compromise between cost and effectiveness.

    For my second build (spare bike) I will test the rag joint out.

    What kind of effect have you seen with take-off using it? Do you need to moderate thrust, or is a simple gradual increase in throttle enough to keep it from tearing spokes? Also, what size spokes and wheel are you using? The gross majority of the 26" bikes in my area that fall within my budget utilize 12ga spoke wire, which is why I am so leery of utilizing the rag joint as an initial method for my primary.

    What advice can you give me if I do end up using it? Would placing hard rubber block spacers between the spokes to off-set the applied torque be an effective deterrent for spoke snap, or even filling in the entire area with hardened rubber and drilling through it for the mounting bolts?
  6. crassius

    crassius Well-Known Member

    as with all these that don't use the centrifugal clutch, one needs to gently engage the clutch while pedaling the bike from a stop (even while the engine is running)

    heavier spokes are not needed unless one is brutal with the clutch

    one must find the time or resources to get used to a whole bunch o' things if reliability is expected
  7. Anhevius

    Anhevius New Member

    Oh, I fully admit there will be a learning curve with learning how best everything works. I'm just trying to eliminate the most costly portions of such.

    Though now I am wishing I was still in the US. I had access to fabrication equipment there and could build my own hub, or modify one to suit.

    I did have a thought though. I'm going to see about welding a brass washer to the original hub on my bike, with the sprocket welded to it. Using a mig welder on two to three should still give me a good bead and set, and would provide a solid support for the sprocket until I can invest in a more expensive system. Though I'll have to look at the various models available and see how their hubs are built. I'll need to find one with a good steel body, aluminum is too soft for that kind of welding work.
  8. crassius

    crassius Well-Known Member

    you still need a way to true that rear sprocket
  9. Anhevius

    Anhevius New Member

    That isn't really that hard, if you know what you're doing. The easiest way if you go with the welding idea is to get a brass washer with an ID that makes it snug onto the wheel hub, and an OD that sits flush inside the opening on the sprocket. Weld the washer to the sprocket first, then with it loose put the wheel on the bike and mark out the location where the chain lines up properly. (I like to use a spot of epoxy to set it and spin the wheel to ensure it's lined up), tack weld it in a few spots to get it secure, test again to ensure it's stayed true, and then finish the welding, grind the weld smooth and coat with clear nail polish to prevent any oxidation issues (after it's cooled completely! Burning nail polish smells horrid.)

    The main thing is taking your time and not getting too anxious to do the job. This comes from years a mechanic for a demolition company. My most common work was converting equipment with blown motors to accept a Cummins 5.9 Diesel. Far cheaper than buying new motors (Less than 5k for a brand new long block vs over 50k for a short block), and most of the work was with mounting the motor so that it lined up with the take-off for the hydraulics. Same basic principle. Mount engine with either a direct gear from the flywheel, or a chain-drive system using horrible geometry that makes you wonder if the designer was on drugs.

    I will most likely buy the pre-built wheel, and do the welded sprocket to the stock one, to test how it works. It might and it might not. The metal might be too soft or thin to take a proper weld that will last. I'd love for the welding option to be fully viable, since it would mean a much lower cost and time frame for building more bikes. Shipping to Australia from the US is absolute murder on the wallet if you want it faster than 'eventually'.