Chain Tensioner chain tensioner? lost 2 chains

Discussion in 'Transmission / Drivetrain' started by noble b, May 25, 2012.

  1. noble b

    noble b Member

    the chain tensioner that comes with these bike kits seems like ****. just went to the store not even 2 miles away and almost lost the 3rd chain because on the supped thing. do i even need this or is there some other alternative i can use?



    The tensioner is needed in most builds. I do have one bike that (after the chain had stretched) I was able to adjust everything with out one. All my others use them.
    I have two with over 1000 miles on the stock tensioners. Like every thing else on these bikes, if you take the time and do it right, it will work.
    A chain jumping off is ether so sloppy loose that it can lift off the teeth or its out of line.
    I would start there. Get behind the bike and sight up the chain it needs to be dead straight. If you use the bigger 415 (I think that's the number) chain you can get away with a LITTLE off set but still not much.
    If all is good there, adjust the chain and spin the wheel. Check that the tension remains the same. If the sproket isn't centered the chain will go tight then loose....tight, loose.....If it's bad enough and you happen to adjust it on the loose spot, when the tight spot comes around it can actualy bend or pull the tensioner over!
    Well that's a place to start. Check that and let us know!
  3. darwin

    darwin Well-Known Member

    Fix it , others have. search.
  4. KCvale

    KCvale Motorized Bicycle Vendor

    Jumping chain is not the tensioner, it's your rear sprocket or wheel.

    All the tensioner does is take up any slack for the chains non-powered return trip to the back sprocket.

    A chain tensioner will NOT bend chain around a wheel.
    Stand at the back of your bike and look at how you mounted your sprocket, it has to line up with the motors sprocket and the most common thing people get wrong with all these DIY builds.

    The only solution is to take your back wheel off and remount that sprocket properly.
    Make sure it is cupped the way that works best for your bike.
    Then verify it has no wobble vertically or horizontally when you spin it.

    Better check your rear wheels bearings as well, if you can move your back wheel back and forth (as in side to side slop) you need to correct that.
    If it happens to be a $100 Huffy chances are it's already toast but worth a look.

    Hope that helps.
  5. wally

    wally Member

    If the sproket isn't centered the chain will go tight then loose....tight, loose... end

    Not quite, my small sprocket is oval :-(! Therefore I can never get it just right. Just right is tightish on the tight spot. I have yet to loose a chain. Mine are aligned straight.


    Yes wally
    as long as it's straight you can get away with some play in fact, I have run some real loose chains but they were aligned properly and always got me home!
  7. KCvale

    KCvale Motorized Bicycle Vendor

    Your motor sprocket is oval? Never seen that but as also mentioned a little loose will work but not a crooked rear sprocket with lateral wobble and the worst of all of course is the 2 sprockets not aligned to begin with.

    My helper and I have down pat.
    A drill with a 10mm socket and 10mm box end wrench.
    We stand the wheel up between our chairs and one works the drill from the outside the other holds the wrench on the inside.

    Also keep in mind you tighten those 9 bolts like a car wheel, in a star pattern, and check the center position as you go to avoid vertical wobble.
    One other tip, if you have the sprocket on just firmed up and the vertical center is off a bit, stand the wheel up with the high side pointing up, lay a piece of chain in the sprocket teeth, and give it whack with a hammer ;-}
  8. noble b

    noble b Member

    thanks all i will be in my garage most of the day trying to fix this thing. i feel lost not able to ride.
  9. KCvale

    KCvale Motorized Bicycle Vendor

    I know the feeling, especially when I tend to ride high end shifters which by the way are harder to build than than a direct drive but you don't have to mess with the rag joint rear sprocket ;-}
  10. noble b

    noble b Member

    alright most of the day spent messing with the chain and a few other things and got it going. lined the chain up well straitened the sprocket as good as i could get it got new bolts for the chain tensioner (a must you cant get enough tork on the Chinese ones). moved the chain tensioner from the back close to the sprocket and the wheel that was close to the bottom to the front closer to the engine and to the top witch i think was the main problem with my chain breaking cause the corner would catch the chain. but thank all cause all of these things needed to be done. and my bike runs again.
  11. KCvale

    KCvale Motorized Bicycle Vendor

    Glad to hear you got it running proper now and you're welcome ;-}