Clamp Hub Adaptors for Rear Sprocket

Discussion in 'Motorized Bicycle General Discussion' started by Nehmo, Sep 28, 2017.

  1. Nehmo

    Nehmo Member

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    With a Cranbrook, the rear hub is 1.5 inches in diameter.
    I had the chain jump after very soon after completion of the engine installation. I don't like the uncertainty of centering with the rag-joint sprocket. If it's not centered properly, the chain will go loose-tight on every rotation. Thus, I'd like a more certain system. The jackshaft arrangement using the original pedal chain for drive seems the best, but suppliers want $200 + for them. (I paid $500 for my car, to give you an idea of where I sit on the economic heap). I'm considering a hub clamp.
    Does the typical 9-hole sprocket 44-tooth supplied with the motor kit, fit on a 3-bolt adapter (like the bottom one pictured here)? Or do I need to buy a new sprocket too? [​IMG]
    The hose clamp ones looks lame. It doesn't seem a hose clamp will provide enough gripping power.
    [​IMG]
    I'm considering this MOTORIZED BICYCLE 1.5" CNC THREE POINT HUB ADAPTER from eBay's
    mzpartsmiamimzpartsmiami (6546 ).
     
  2. Chaz

    Chaz Active Member

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    The rag joint works well if installed correctly. Over 5 years on mine with maybe 4 adjustments for parallel in that time. Maybe you need to file out the center hole to make it a little bigger.

    I thought the "hose clamp" adapter was lame too until one of our members clarified the application. It is used with the rubber rag joint donuts. The hose clamp design just makes the installation easier and more accurate.

    If you get the three hole adapter you will need to buy a specific sprocket. Unless you have the equipment and skills to drill the three holes in the stock sprocket.
     
  3. Nehmo

    Nehmo Member

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    I know the arrangement has its fans, but the time it takes to center it alone is enough of a disincentive to use it. Besides, 0.8 adjustments/year is too many. The centering should be accurate.
    Yes, I considered enlarging the center hole on the sprocket, but I was afraid to. I don't have a means (that I can think of) to exactly enlarge the hole in all directions.
    OK, now it makes sense. The vendors of these parts are rather illiterate. There hardly ever is a paragraph explaining a part.
    A simple drill press would be enough, but I don't have one.
    Actually, $40 USD is not ridiculous. But the price issue is relevant when the eventual plan is to change to a jackshaft arrangement. Then the hub clamp is extra parts.
    I also need a new chain tensioner. The original was destroyed in the above-mentioned chain jump.
     
  4. xseler

    xseler Well-Known Member

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    I have the adapter from mzmiami........it's a great piece and I've got lots of miles on it with zero issues!! 5 thumbs up for this product! Seems like I got the sprocket (36t) from them as a package deal.......
     
  5. Chaz

    Chaz Active Member

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    Well, I said the adjustments were for parallel alignment, not centering. The centering was dead on since day one.

    You can enlarge the hole with a round file, or even coarse sandpaper and a lot of patience. The hole doesn't need to be perfectly enlarged. Just large enough for the sprocket to sit flush on your hub. Check out how others have done it with the coaster brake.

    You can get an adapter like exseler and consider it an investment for a future build.

    I gave you the advice above because you don't want to spend unnecessarily. That's all I can do. I give up.
     
  6. Nehmo

    Nehmo Member

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    I didn't mean to criticise your advice, nor do I discount it.

    Maybe the left-right alignment was the problem in my case too. When I put the sprocket on, I saw conflicting advice on which way to dish it. I decided to use with the teeth more inward (or right) because the person giving that advice seemed more authoritative than the other. The 2 sprockets seemed to be on the same plane when I was done. But how can you tell?
    I used a straight edge as best as I could, but, as you know, the sprockets aren't positioned well for that test.

    But I was rather suspicious of the rag joint from the beginning. I never was I00% satisfied with the centering.
    I also may have had too much slack in the chain (which was taken up by the tensioner), and that may have been a problem.

    In any case, I'd like to solve the chain-jump problem permanently. In car engines, sometimes timing chains have much more power going through them, and they stay on for an incredible number of turns.
    Gates makes CarbonDrive cogged belt that I like (pedal side). I tried to buy the setup a few years ago, and their distributor failed me. Maybe they've improved their sales system since then. They require special sprockets, and I wouldn't know what was needed.

    For now, I suppose the solution is a jackshaft kit, and a 3-speed internal rear hub.
    It's a lot of money.
     
  7. indian22

    indian22 Well-Known Member

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    Nehmo I've just gone through both your threads and the advice given is solid so I'll address your stated original problem with the build. Bike threw chain, with included kit tensioner installed. It's a common problem for new comers to motorized bicycling, heck it's common wherever chain & sprocket technology is used, but on a kit bike setup 99% of the problem is due to improper setup/installation of the supplied kit parts. Unless you are really wanting the very real benefits of "shifting" which not only is expensive but also involves "correct" installation and setup, then the (almost) zero cost benefit of setting up the supplied kit parts correctly is the answer to your original problem.

    A straight "chain line" from engine output sprocket to rear axle sprocket is essential and this is achieved during setup by making certain the engine is secured straight in the frame as well as properly secured to the frame. That done the sprocket is attached to the rear wheel. I haven't used a kit rag joint setup since I discovered the sprocket hub adaptors maybe 6 years ago, but using what you have will also work with narrow tires/wheels. I like to mount the sprocket with teeth as far away from the spokes as possible, to help the chain clear the rear tire.

    Once both the rag joint/wheel & motor to frame are properly installed I loosely mount the rear wheel & center it. Then fit both pedal chain & drive chain for length. I usually don't get in a hurry to break the chains to length, but use a zip tie to hold them in place on the sprockets, while I check out the chain lines, just eyeball at this point for straight & by putting pressure on each chain with the hand to act as a tensioner check the chain to tie clearance as well. Chain rub on either side will eat a sidewall in no time.

    The chain should be checked at the motor sprocket for correct seating, the rollers feeding smoothly and rollers completely settled down in the sprocket. If this is not the case the sprocket needs to be removed and both sides lightly thinned on both sides until the chain seats properly. I use an 80 grit flapper disc in an angle grinder for the thinning operation. Don't alter the height of the tips of the sprocket just the inside and outside of the sprocket and no lower than where the chain touches the sprocket. Very little material need be removed maybe 1/64" or so total. Chain will now run smooth as glass.

    Chain length now needs to be addressed, both chains 'cause if they are flapping around they gonna rub And come off as well. 1/2" to 3/4" total deflection at mid chain is what I shoot for on both chains, this is where a quality tensioner comes in handy. I like the spring loaded tensioner that mount's on the motor cases best, as they absorb any minor inconsistency in the sprocket mounting concentric's. They can't get into the spokes either, like the kit units are prone to do when poorly fitted or maintained & that is a big safety concern.

    I like the side to side adjustment of the 3 hole sprocket to hub adapter, it's a quality design that's so simple to install. Concentric and adjustable horizontally to help setup a straight chain line and or fit larger tire and wheels with chain clearance. If you run a coaster brake setup with the 3 hole sprocket make sure the sprocket has a very large center hole to clear the required modified brake arm lever as well. Well worth the money.

    Of course all the above just brings us back to good installation and fitting the rear wheel with proper spacing has to be mentioned, having some axle spacers on hand is a part of this centering, truing & securing the wheel, while keeping chain lines straight and clearing both tires and chain stays and retaining proper chain tension on on both peal and motor drive sides.

    You may be. well aware of all this information, Nemoh, but others may benefit from my poor (yet lengthy) explanations.

    We can run but not hide from good installation practice. It's foundational. Best of luck. Rick C.
     
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  8. Chaz

    Chaz Active Member

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    Great information, Rick, and well written. I really like the idea of thinning the sprocket teeth. I have read about it on this forum before (possibly from you) but completely forgot about it. I haven't had a need to do it but will probably do it on a future build just to make it smoother and avoid problems.

    Nehmo I would try the tooth thinning which might be just the ticket for your bike.

    good luck
     
  9. indian22

    indian22 Well-Known Member

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    Thanks Chaz most of what I touched on has been addressed in posts by others on our various forums, but thought I'd gather these thoughts into one post. New kit builder's are often disappointed in their builds and certain aspects of kit components & I'm sensitive to this. Instructions are minimal at best and even Youtube videos are often lacking in any detailed information concerning the absolute minimum of basic knowledge to build a safe, working bike, let alone one that is enjoyable to ride. I identify with any builder that wants to understand why as well as how, but would caution new moto bike builders to get the first bike built & much riding & maintenance time invested before twisting off into adding more complex elements to their builds...especially if money, tools and mechanical experience is limited. I fear many motor bicycling enthusiasts are lost to the hobby before they understand how much fun it is to motor around on a dependable motor bike because they are left to do the first one their own way. I'm a mostly retired machine shop owner and many time certified welder who has built, modified and restored literally dozens of motorcycles, rods and custom cars over the last 60 years. Even so I spent a year researching how to correctly build a motorized bike with a China Girl before purchasing my first kit and still made some basic errors in that build which cost more dollars in parts and time than was necessary. It is still my favorite bike & has many hundreds of hours of riding time on her, but bears little resemblance to the original build, each part on the frame has been changed out several times as I tested and tried new things, but the basics described earlier once learned still remain. I'd hope to spare others that cost or perhaps even injury, but of course each builder is free to strike out on their own & perhaps it will work out just fine... Rick C.
     
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