Chain Tensioner/Guide

Discussion in 'Motorized Bicycle General Discussion' started by JDUBWEB, Jun 25, 2008.

  1. JDUBWEB

    JDUBWEB New Member

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    Hello All. I finally purchased the bike engine kit and have it installed. What a fun project. I got to ride my new motorized bike for about 8 miles before the chain tensioner/guide screw was stripped and useless. Now, I have to find a replacement or better solution. In browsing some of the forums, I see a lot of mods and interesting work around for this. I have been to every hardware store and bike shop in town and cannot find anything that will do.

    Any suggestions

    1) Buy another crap replacement chinese part?
    2) One bike shop offered a guide that is used for tandem bikes. It looks like it "could" work, but the teeth are not too deep. Also, it does not have a groove like the part that came with the kit. I saw one post with someone that had soemthing similar. Could this work?
    3) I have been referred to a metal fabricator to try and provide the stripped bolt that holds the plastic tensioner/guide in place.

    I appreciate any advice or suggestions you have. I appreciate your help.
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Have you tried to press out the bolt that is stripped from the roller? It should come out with light whack.

    How about replacing the roller assembly with a bolt and a skateboard wheel?
     
  3. JDUBWEB

    JDUBWEB New Member

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    Yes, I got the bolt out, it was stripped. That bolt is a proprietary piece that holds it on, but allows it to spin. The local motorcycle shop had a piece that would be similar to the skateboard wheel, but there is no guide on there. How important is the "guide" aspect of the groove in this piece?
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    It's (the groove) not, the chain just runs across the roller, it's not really a guide, but more a way of facilitating chain adjustment on a wheel that already has one chain on it.

    Don't get the chain too tight. 3/4"-1" of play will do it.
     
  5. Norman

    Norman LORD VADER Moderator
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    I drilled out my center bolt( used a metal lathe) that mounts the chain roller and inserted a usa(american) bolt in its place that I can reef on and not strip I think the bolt is a 5/16" dia
    I have a post on this forum showing what I did as well but then again I'm not the best at using the search but if you look for them that I posted you will run into it someday.:confused:
     
  6. deacon

    deacon minor bike philosopher

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    If it were me, and if it is a coaster brake type bike. I would set the bike rear wheel for the motor chain without the tensioner, then put the tensioner on the bike chain with just a bolt and nut to hold the wheel in place. Since the bike chain will get very little use ,all it will do is keep it tight. It won't need to spin.
     
  7. JDUBWEB

    JDUBWEB New Member

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    My sprocket for the engine is on the opposite side of the 7 speed pedal power sprockets. Pedal is on the right and engine sprocket on the left - looking from the rear.
     
  8. misteright1_99

    misteright1_99 New Member

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  9. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    There ya' go.
     
  10. JDUBWEB

    JDUBWEB New Member

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    Thanks. I ordered these parts from TSC and they should arrive next week. Thanks for the advice. You guys are great.
     
  11. jasonh

    jasonh New Member

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    I know this is a little late, but as far as the skateboard wheel, you could probably just turn it on a lathe or something and cut a groove into the wheel for the chain to run through.

    But I like the TSC method better anyway :)
     
  12. misteright1_99

    misteright1_99 New Member

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    If you need any help or have any questions PM me and I'll be glad ro help......
     
  13. MrLarkins

    MrLarkins HS Math Teacher

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    is the chain tensor even necessary? I mean, I might just take mine off and slide the axel back farther into the slot...what are the possible cons of this down the road?
     
  14. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Not much adjustment. That's O.K. if you get lucky and get a chain that doesn't stretch much...good luck there.
     
  15. fuzz

    fuzz New Member

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    easy fix ,stop using the tensoiner , get rid of it . buy a chain break and shorten the chain (^) beer


     
  16. MrLarkins

    MrLarkins HS Math Teacher

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    does the chain ever stop stretching? after how many miles would it be done?
     
  17. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    One bike I had, the chain stretched for 300 miles!!!! The other was less, around a hundred.
     
  18. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Then you may have problems if you are too tight with one chain length, to loose by adding a link...then what? Go find a half link and mess with that, then remove that when the chain gets loose?

    If done properly, the tensioner will last a good long time and make chain adjustments easy.
     
  19. jasonh

    jasonh New Member

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    I guess you could also try just pulling an old junk derailleur from somewhere and use it, assuming it's still got some "spring" in it....
     
  20. Technomancer

    Technomancer New Member

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    My tensioner is junk too.. just lost my chain today.
    ground it up in the spokes and all over the road. it could have been worse. the extra bolt i added held level pretty well though.

    i was lucky enough that my kits junky flat head screw and bolt set up was easy to separate.
    since it just dropped my chain it was loose enough to remove.
    (even after i used thread-locker and tightened it down as much as humanly possible with a flat head on one side.)
    now i just need to replace this with a bolt with a good one and all is well.
    *as i wait for a new chain to arrive*

    almost got this and added a new hole to the frame though:
    http://www.amazon.com/Godspeed-Single-Tensioner-Sealed-Bearing/dp/B003527E3G/ref=pd_sbs_sg_2

    here is what it looks like (mostly) taken apart:
    [​IMG]

    Better: M8 x 45 Bolt with M8 Nylon Locknut (Locktite on install)
    [​IMG]
     
    #20 Technomancer, Apr 18, 2011
    Last edited: Apr 18, 2011

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