Brake lever as Chain tensioner or Pizza Cutter

Discussion in 'Motorized Bicycle General Discussion' started by Technocyclist, Jan 10, 2009.

  1. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    Hi Guys and Gals,

    I have the shifter kit, and noticed that the chain on the left side can sometimes touch the crankcase at the lower part where a bolt goes through. So I needed a chain tensioner that would not affect the alignment of the jackshaft. I have an old shifter which I removed because I'm now using an internal gear hub. I also have brake levers. So I disassembled one of the sprockets on my old shifter and tried fitting it into one my old brake levers. And viola!!! instant chain tensioner. It fits so perfectly together... Oh yeah, it does look like a pizza cutter... who knows... maybe you can also use it to cut pizzas...laff

    I used 2 pieces of 3.5" Hose Clamps to mount it. Now, the chain rolls sooooooooo smoooooth. Oh yeah!!!

    I also inserted nylon tubing into the hose clamps so it would not ruin the paint on my seat tube.

    I also inserted 4 washers or spacers to align the sprocket with the chain.

    With this tensioner it will also enable you to install bigger sprockets on the jackshaft for more torque...

    BTW, better ask Paul or Ghost of SBP before installing. It may void your warranty...

    I think this chain tensioner can be used in many ways and not only on the shifter kit.

    So? what you think? Chain tensioner or Pizza Cutter? or both?
     

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    #1 Technocyclist, Jan 10, 2009
    Last edited: Jan 10, 2009
  2. Spunout

    Spunout MB Builder Extraordinaire

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    nice work!

    its amazing what a guy can drum up, when he has to do some thinkin'.
     
  3. old motorbike

    old motorbike New Member

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    Great work... ingenious.
     
  4. unraw

    unraw New Member

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    never thought of that. Good idea!
     
  5. TexasDav

    TexasDav New Member

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    Wow I just love how the minds work on this forum, talk about thinking outside the box, I don't think you could put the people here in a box to begin with. They are too much free thinkers to fit into the regular population that is probly why we ride what we do instead of something already made for us like a scooter or motorcycle.
     
  6. Spunout

    Spunout MB Builder Extraordinaire

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    excellent point.
     
  7. TigerToothBikes.com

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    I think you're absolutely right. Many would scoff at us and call us crazy. Others would take one look and say "can't be arsed" or "might as well buy one". But it never ceases to amaze me how chaps here come up with simple yet clever solutions to sometimes quite complex problems.
    Some of the builds i have seen have been not only beautiful but also superbly engineered (sure you get the "death traps" now and then.bf.).

    Excellent work!
     
  8. jasonh

    jasonh New Member

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    Very cool idea.

    I wonder....my right side chain on my shift kit is always loose (didn't bother to order their tensioner...oops), I wonder if I can rig up something like this for that chain...
     
  9. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Technocyclist - Very ingenious, but your left chain should not be so slack in the first place. I'm wondering if you have an interesting variant engine or an alignment problem. Can you post or send more pictures of your installation?

    JasonH - A proper movement tensioner and retainer is preferred to a contact tensioner. The roller and contact will rob (a small amount of) power.
     
  10. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    Ok, so I have been using this chain tensioner for a week and it was'nt so stable as I thought. The sprocket tends to move sideways, so the side of the chain still touches crankcase. So to solve this sideways movement, I put a larger washer, a drawer washer to be exact. The larger washer rests on the bottom engine mount preventing the sideways movement. Going to test again... I also upgraded the jockey pulley sprocket to bigger ones with sealed ball bearings.

    Pablo,

    I found that the chain was loose at 15 links, so I tried installing a motorcycle chain with 15 links, but it was too tight. So I tried removing a half link - I am using halflink chains, could that be that the problem? -anyways, so I removed a half link, but it was also too tight. I also tried 16 link motorcycle chain, but it was too loose...

    Here are some additional pics...
     

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  11. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Thanks for the pictures. Yes there is enough difference in chains to make the link count only apply to the 415 chain. Why can't you just use the 415 chain? Also, you can ever so slightly slot the left plate to pull it rearward, of course making sure everything stays very well aligned.

    Did your engine come with those studs?
     
    #11 Pablo, Jan 18, 2009
    Last edited: Jan 18, 2009
  12. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    I upgraded the bolts to studs, also on the right side, so I can easily remove the clutch cover. I did try 415 chain, but it was too tight. I could'nt put the master link to connect the chain. And 415 chains are very heavy... :) I already slotted the left plate, but still won't fit. Also, I was afraid that the jackshaft might get misaligned.
     
    #12 Technocyclist, Jan 18, 2009
    Last edited: Jan 18, 2009
  13. fm2200

    fm2200 New Member

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    my experience with with motorcycles and the rpms they produce leads to believe that although your idea is very creative it would probably need almost daily lubrication because of its intended use on a multi-speed bicycle, the wear a tear is probably 5 times greater on your gas bike. Let us know how long it endures the everyday use you give it.
     
  14. Spunout

    Spunout MB Builder Extraordinaire

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    i wonder if it would help, to use an already-stretched chain
     
  15. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    I can tell you that our supplied bike chain simply does not stretch that much.
     
  16. fm2200

    fm2200 New Member

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    when chains are too tight, get a half link or two that will give you more chain (one half link will probably be just right)
     
  17. fm2200

    fm2200 New Member

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    can you reposition the jack shaft by sliding it upward and getting a longer chain for transfer side or is that not possible. Another thing I would consider just cut that piece out altogether it looks as though Its only function is to hold that cover on. This problem your having is giving me second thoughts on getting one of those jack shafts.
     
  18. Technocyclist

    Technocyclist Motorized Bicycle Senior Technologist

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    I guess the best option is to reposition the jack shaft a little bit higher. This would also mean that I would have to disassemble the whole thing, and re-align everything again. It would be just a lot easier to install this chain guide or tensioner. That's just plain laziness...I guess when I first installed it I did not foresee this problem before and just aligned the jackshaft without considering that the chain would sometimes hit the crankcase.

    Also, I did'nt use the supplied chain, because I thought BMX half link chains would be better.

    Don't get me wrong about the shifter kit. It's the best thing that ever happened to the motorized bicycles. Even with all these problems, it's all worth it... :) Given all the benefits it offers... .shft.

    Nothing is perfect in this world and we learn to cope up with these small imperfections. Maybe Pablo will come up with a better version of the shifter kit in the near future.
     
    #18 Technocyclist, Jan 19, 2009
    Last edited: Jan 19, 2009
  19. Ghost0

    Ghost0 New Member

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    Of the almost 300 kits out in the market not one person has had any issue using the standard engine kit supplied 415 chain. Whenever a new assembly is put together everything should be a little tight. This allows for some break in. If you start loose it will only get worse. Honestly, the few issues we do have are directly related to the customer incorrectly installing the kit or altering it in some adverse way. All I can say is if the kit is installed exactly to the instructions there will be very few if any problems. We have even replaced parts for customers that have made mistakes during installation. Customer satisfaction is #1 on SBP priority list.
     
  20. jasonh

    jasonh New Member

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    I would honestly just ditch the half-link chain for the left side and go with a normal 415 or #41 chain. I'm willing to bet you'll be fine with 15 links with that. And really, it's such a small piece, I don't think the weight is a big deal.

    I am using a well-worn stock kit chain, and it's a little loose, but probably only what would be expected - certainly not enough for it to rub like that. If you still had the issue with a stock kit chain, then I'd say you might have one of those cases where your motor is a bit different from the rest...

    Ghost0 - wow, 300? Nice job :)
     

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