Tensioner Pulley Too Narrow- Mtbr.com
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  1. #1
    JP3
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    Tensioner Pulley Too Narrow

    I just bought one of these [DMR STS tesioners]:

    http://www.dmrbikes.com/?Section=pro...s&itemid=CDSTS

    In addition, I bought a KMC Z710 KOOL BMX BIKE SILVER/BLACK 1/8" CHAIN.

    I did not read the fine print on the tensioner that states that it is "Designed to run with a geared chain..." In short, the chain is too wide to fit into the pulley.

    Questions:
    Is it possible to buy a wider pulley? If so, where and what kind?

  2. #2
    Retro Grouch
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    Quote Originally Posted by JP3
    I just bought one of these [DMR STS tesioners]:

    http://www.dmrbikes.com/?Section=pro...s&itemid=CDSTS

    In addition, I bought a KMC Z710 KOOL BMX BIKE SILVER/BLACK 1/8" CHAIN.

    I did not read the fine print on the tensioner that states that it is "Designed to run with a geared chain..." In short, the chain is too wide to fit into the pulley.

    Questions:
    Is it possible to buy a wider pulley? If so, where and what kind?
    This has been a common problem with tensioners. Today you do have some 1/8 chain choices. Rennen and Surly have redesigned their tensioners for 1/8" chains and the Sette (Pricepoint;modeled after the Rennen) is the least expensive. As far as buying a different roller, I'm guessing not. The price of an individual roller would probably exceed buying a complete part.
    Just one more rep and I get the toaster!

  3. #3
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    You could simply put on a cheap geared chain. Either way your probably going to be buying either a new tensioner or chain.
    Big Foot Blue KHS XC704r

  4. #4
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    That's weird it won't work. I run a 1/8" chain and rear cog but have a 3/32" front chain ring with no problem. I always thought a 3/32" chain won't work with 1/8" gears, but the other way is fine. Did you try it out on the bike?

    If it's a matter of the chain hitting the sides of the pulley, you may be able to put a washer on both sides of the pulley and widen the cage a bit. Never tried it, but it might work.
    "Doing the right thing" is like water. It's good for all living things,and flows without thinking about where it's going.

  5. #5
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    I am now using that tensioner and it seems to work great so far. My 8-speed Sram chain fits nicely in the pulley

  6. #6
    Retro Grouch
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    Quote Originally Posted by mountainflow
    That's weird it won't work. I run a 1/8" chain and rear cog but have a 3/32" front chain ring with no problem. I always thought a 3/32" chain won't work with 1/8" gears, but the other way is fine. Did you try it out on the bike?

    If it's a matter of the chain hitting the sides of the pulley, you may be able to put a washer on both sides of the pulley and widen the cage a bit. Never tried it, but it might work.
    The tensioner JP3 is using does not utilize a standrad derailluer pulley, it uses a grooved acrylic wheel and the groove is not wide enough to accept an 1/8" chain.
    Just one more rep and I get the toaster!

  7. #7
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    Quote Originally Posted by aka brad
    The tensioner JP3 is using does not utilize a standrad derailluer pulley, it uses a grooved acrylic wheel and the groove is not wide enough to accept an 1/8" chain.
    OK, I see. Well if the OP is running standard 8/9 speed cog and chainrings with a 1/8" chain, then a new chain is probably the easiest. If he's running 1/8" all around then he needs a new tensioner. Maybe he can return it?
    "Doing the right thing" is like water. It's good for all living things,and flows without thinking about where it's going.

  8. #8
    JP3
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    Thanks!

    New Chain on the way!

  9. #9
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    I am in the same situation with a 1/8 chain that is slightly wider than the grove in the rubbber roller. I replaced the roller with a jockey wheel from an old derailleur and reset the tension.So far so good.

  10. #10
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    the Surly Singleator works with 3/32 chains and 1/8" chains. i had one but the spring died after a few rides. i was not impressed.

  11. #11
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    I have run jocky wheels on tensioners in the past.An easy modification.

  12. #12
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    I have the DMR STS tensioner and it also wouldn't accept the wide KMC 410-HX chain. Luckily I had double chainring chain guide which had a wider polymer pulley that was swapped for the stock narrow DMR one, works like a charm now.

    As others have suggested the idea of using a derailleur pulley is a good advice and I don't see why it also wouldn't work with the right adjustment.

  13. #13
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    im having the same issue with this tensioner. im using the sram pc-1 chain. it is really tight but it does work. im hoping that it will eventually just wear it self a groove into the pully and loosen up. i may pull the pulley off and try to grind some material away to speed up the process because it does add some unwanted resistance.

  14. #14
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    well my pulley is fixed. nothing that a dremel cut off wheel cant fix

  15. #15
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    Dammit, this just happened to me as well. No mention on the Jensen website that it doesn't accept a 1/8 chain. Guess I'll be writing a review and heading to REI for a new chain or seeing if the Dremel is a possibility to widen the roller.

  16. #16
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    Dltd
    Last edited by 1SPDBING; 03-15-2014 at 06:05 PM.

  17. #17
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    It was a lot easier to buy a new chain. Maybe when ai get around to upgrading my rear cog I'll upgrade to a better pulley as well and make use of the 1/8 chain then.

  18. #18
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    I use bearings covered with PVC pipe.

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