Chain Tensioner Chain Tensioner

Discussion in 'Transmission / Drivetrain' started by Duhawki, Sep 16, 2008.

  1. Duhawki

    Duhawki New Member

    Who makes the best, strongest, most solid chain tensioner?

  2. mralaska

    mralaska Member

  3. jmccrury

    jmccrury Member

    I agree with mralaska. I see no need for the tensioner unless you are wanting to install the chain guard and have it cover all of the chain. I accidentally got rid of mine because I removed too many links from the chain, but it was one the best things I did to my bike too. I like the shim idea, but if your rear wheel can be adjusted, you can also just remove links from the chain and move the rear wheel to the appropriate position.

    mralaska - I thought it was funny that you have the 50cc slant head on a $5 yard sale bike because I also have a 50cc slant head on a $6 Good Will mtn bike.
  4. iron_monkey

    iron_monkey Guest

    You need it so that the chain will not jam in the engine at high speed, which is a very dangerous situation.
    This is unless you are lucky enough that when you shortened the chain to the maximum allowable, it is adequately tight already and the chain wont stretch from then on (unlikely).
    Mine did, alot. It stretched enough to pose a danger, but not enough for me to be able to shorten one more link. Hence the need for tensioner.
  5. mralaska

    mralaska Member

    Removing one link of chain shortens it by one inch. One inch of slack in the chain can be fully absorbed by 1/2 inch of adjustment because every inch you move the tire from the engine is twice that on the chain. A total of 3/8 inch adjustment is all you will ever need to keep a chain properly adjusted. Some bicycles, as noted above, are able to adjust enough by moving the tire. I found it easier to move the engine away from the tire with shims because the tire kept going crooked when I tried to adjust it at the tire.

    The tensioners are a simple concept out of the box and I was even planning on adding a spring loaded tensioner to my bike to take up for chain 'stretch'. However, since adding the shims the chain has not stretched. I made three shims but it was too tight so I only put in two, the bike still will not take that third shim. I went through the first tank of gas with a tensioner, three tanks since then with the shims. When I had the tensioner it was a pain to keep in place and everything had to be perfect or the chain would throw. Since adding the shims the chain runs as smooth as a motorcycle and the chain has not thrown once. I live on the side of a mountain so it gets its share of both stress and speed.

    The tensioners, especially the improved ones, might be desireable for some applications but in no way, shape, or form can I imagine a 'need' for them.
  6. MotorMac

    MotorMac Member

    This forum is terrific,I took my tensioner off completly and removed 2 links from the chain pulled the wheel back and now its tight and quieter too!! thanks guys for your experienced advice! MAC
  7. s_beaudry

    s_beaudry Member

    I have retighened the tensioner 5 or 6 times already, and have also removed one link from the chain as well.

    Just went for a 27 miles ride with her and the chain is still pretty tight on there.

    Not sure if I would run without a tensioner or not, seems kind of risky without one.
  8. Maxx Ported

    Maxx Ported Member

    I never use a tensioner again, I shim the engine forward... If you really want to use one, I found it safer to move it forward. so it CAN't twist into the should explain

    Attached Files:

  9. spyke hyzer

    spyke hyzer New Member

    I've been running my MB without a tensioner from the start. I upgraded to a #41 chain and was able to get a half link for it. I am able to adjust the tension on the chain by adjusting the engine in the frame, I have a Trek mtb and had to fabricate my motormounts from steel plate and muffler clamps. I have about 200 miles with no chain issues and haven't noticed any chain stretch.
  10. s_beaudry

    s_beaudry Member

    I am starting to think that replacing the chain with a good quality #41 would be the first major upgrade that one should do during assembly!
  11. That is one of the first items I replaced with #41 chain and also replaced the carp kit tensioner with a spring return tensioner, so far about 500 trouble free miles, and havent adjusted the chain once...........
  12. mralaska

    mralaska Member

    Sometimes I wonder if some of the 'stretch' some people are seeing is actually the stock tensioner failing on them. Personally I have about 250 miles on my stock 415 chain and seen no change in tension since using the shims. Granted, I do have the smaller engine, but I am working it pretty hard hauling my 230lb (okay, maybe 240lb) butt up and down the side of a mountain every day.

    I do like that spring loaded tensioner, though, and will probably pick one up next time I get a chance just to have it on hand in case I am feeling lazy if my chain does start to stretch/wear.

    I think we can all agree that the stock tensioner will not work without, at the very least, some tweaking. At the bare minimum you will need to wrap something around the chain stay or bolt it on or do something to keep the tensioner from rotating. My first batch of bent and broken spokes was within 5 minutes of my initial install because I did not have the tensioner seated firmly enough. Even after a few modifications and getting everything lined up perfect I never felt I was able to trust it.
  13. jmccrury

    jmccrury Member

    I have actually thought the same thing about the stretching that people have mentioned on here. From reading the posts, I expected to have to adjust the chain after 20-30mi, but I have gone almost 200mi so far without any change in the tension either. I am also using the stock 415 chain that came with the kit.
  14. LabDude661

    LabDude661 New Member

    I just went to the shim idea on mine and ditched the tensioner alltogether. The chain tensioner is completly unneccecary. If you make your shims small enough, you basically have an infinite level of tensions that you can get through a combination of adding/removing shims, and removing chain links. Those stupid stock tensioners have got to be the most pointedly dangerous part of the in-box kit. mralaska has got it in my opinion. Getting rid of the tensioner smoothed my ride, removed a dangerous spoke tangle hazard, and most importantly simplified the entire opperation. Anytime you can engineer a solid metal solution to a problem, it's going to be the better mouse trap. Oh and I'm using the stock chain. I'll let everyone know if it stretches.
  15. bluegoatwoods

    bluegoatwoods Well-Known Member

    I got rid of my chain tensioner almost immediately and I haven't regretted it. One single-speed, coaster brake type and the other a multi-speed derailleur type. Neither one has given me any trouble. Every now and then the chain throws. I put it back on the sprocket and ride away. dirty hands the only trouble. When it becomes a bit too frequent, then I tighten by pushing the wheel back a bit.

    I'm a bit reluctant to actually advise doing it because a thrown chain does have the potential to be dangerous. But the stock tensioners are no good at all. And my bike has been ridden many miles almost every day since April with no real problems.
  16. mralaska

    mralaska Member

    I would really think about putting some shims in if I were you! A strap of 3/8" aluminum from the hardware bin and a couple minutes with a hacksaw you can make that chain rock solid unless you have clearance issues with the engine itself and have no room to adjust it, in which case a spring loaded tensioner might set you right up.

    For the sake of new or prospective builders reading this thread, I want to make it absolutely clear that while I advocate removing the tensioner, I do NOT advocate simply removing it and doing nothing to take up the slack. A chain not lined up and properly tensioned is not a desireable situation and does carry the potential of both human and mechanical risk.
  17. bluegoatwoods

    bluegoatwoods Well-Known Member

    As a matter of fact, reading this post has made me think a bit about it. Maybe shims, maybe some other way of getting more precise chain tension.

    I probably better not think about it too long.
  18. MyrmidonJuan

    MyrmidonJuan New Member

    If I can adjust my rear wheel, will I be better to take out excess links and adjust the rear wheel as needed...opposed to having a tensioner and/or shims. The slot where the nuts and bolts go into the frame looks like this /o/..the o is the bolt that can be adjusted at an angle. On a tangent, can someone explain these shims to me?
  19. mralaska

    mralaska Member

    Removing one link makes your chain one inch shorter, so if your rear wheel has three eighths inch adjustment it has the ability to compensate within one link worth of adjustment. (Moving the rear wheel three eighths inch takes up three quarter inch of slack)

    I am not sure I understand your bolt diagram. On my bike the rear wheel is a pain to adjust because of the derailer. I have lost track of how many tanks of gas I have been through but I have only tinkered with the adjustment once since inserting the shims. Follow this link for shim pictures:
  20. Junster

    Junster Member

    Thanks for the shim tip. I have "it only goes in one place" drop outs on my frame. The stock tensioner sucked from day 1. Now that things have settled in I was able to shorten my chain enough to remove the tensioner and just one shim did the fit. I feel alot safer and it reduced the vibrations too. Thanks again, I'm too old to be biting the pavement.