Having difficulties...please help

Discussion in 'Frame Mounted Engines' started by Fletch, Oct 1, 2010.

  1. Fletch

    Fletch Member

    Hi,

    I'm really having some issues with the wheel/sprocket/chain/alignment and I've read quite a few threads and tried the usual fixes with no luck so far and I'm really getting discouraged because I really want to get this bike up and running.

    Here's the quick summary so far (I can post pictures later if need be):

    *initial issues with **** coaster break. bent the arm and added washers per Spookytooth instructions. Opened up hub and figured out how the coaster works. Got past that.

    *Had bike running for 2 minutes when chain tensioner was pulled into wheel and took out 2 spokes.

    *Fixed spokes, read up on tensioners... determined sprocket wasn't true and was pulling. I had trued it pretty well I thought. There is left to right movement of the chain on the tension wheel, and you can see as the sprocket rotates where the teeth start to go out of alignment with chain.

    *Re-trued the sprocket as best I could (for hours), up and down (centering) and left to right wobble. Not perfect but as close as I could get.

    *Same problem with chain left to right movement and jumping while just pushing the bike. Noticed that there was about 3-4mm up and down movement of sprocket despite centering it (measuring) and adjusting it before tightening bolts.

    *I read that sharpening the teeth can help keep chain from jumping so I got careless and impatient - bust out the Dremel and start grinding away at teeth. End up ruining the sprocket.

    *My conclusion/observation is that the angle of the wheel sprocket just doesn't match the angle of the engine sprocket well enough. The bottom of the chain is slightly off-centered with the top as you look down on it.

    So now my dilemma or question is how to fix this? I can't just change the angle of the wheel obviously, it needs to be straight. There doesn't appear to be any way to move the engine left or right because of the mounts. the engine looks like it is mounted perfectly BTW.

    I've tried adding the extra 3 metal mounting brackets for the sprocket to push it out some from the wheel, but that doesn't change the angle.

    I'm thinking about ordering one of those pineapple sprocket mounts from spooky so I don't have to mess with sprocket truing at all and i can be certain that isn't the problem, but i really don't think it is.

    I decided to try not using a tensioner at all after bending it so it lined up and seeing I was having the same problem. Unfortunately my wheel slides in at an angle and not horizontally so I can't just pull it back to add tension. Even without a tensioner I still want the chain to be aligned.

    Sorry for the long post... I just want to be sure I've communicated what I've tried already. Thanks in advance to anyone willing to help me, and I have the worlds sharpest sprocket/ninja star now as a 'thank you gift' ;)
     
    Last edited: Oct 1, 2010

  2. Al.Fisherman

    Al.Fisherman Active Member

    Some pictures of what you are working on might help. I have run into a warped sprocket, but have never had sprocket mounting issues as you are having. Then again I enlarge the sprocket center hole to fit the dust cap ensuring a true fit.
     
  3. Fletch

    Fletch Member


    Thanks for the reply. I have to order a new sprocket and I'm going to go with the pineapple mount that spooky sells as well. Hopefully I won't run into the same problem. I will post pictures if I do though.

    I realize now that the bike chain that came with the kit has jumped off for others because it is narrower and less forgiving than the wider chains. Also it could have been bent (the chain).

    Just need to troubleshoot it but I'll get there!
     
  4. GearNut

    GearNut Active Member

    I ditched the whole factory rubber-n-spoke sandwich mount and went directly to a Creative Engineering/ Manic Mechanic sprocket mount from Pirate Cycles.
    http://www.piratecycles1.com/spadandspcb.html

    It fits perfectly and works very, very well.
     
  5. the chainline is critical to success
     
  6. ibdennyak

    ibdennyak Guest

    Trying to picture what you are describing. Sounds like your sprocket is wobbling too much........ooooor your tensioner is following the angle of the stay. Sometimes I could solve the chain jumping problem by twisting the mounting bracket with a large crescent wrench to follow the chain line better. Your stays usually run at an angle to the chain. When you mentioned the chain riding back and forth is what reminded me of that.

    By the way...if you slot a piece of stock and mount it between the chain stay and seat stay, and use this to mount your tensioner it won't go into your spokes.....lots safer.
     
  7. Fletch

    Fletch Member

    I really like the MM mount and wish it was in stock. I've read that it takes a while to get because Jim? is really backed up. I decided to keep the pineapple mount from ST and see how that works because I can't stand the rubber sandwich. Only issue now is that I have no sprocket! I ordered a 40 tooth from ST and the mounting wholes were different- 6 holes drilled very close to the center hole. I have no idea what mount that would even fit on/work with. I don't have a drill press and don't want to mess up another sprocket so I sent it back. Hopefully they will get me one soon because it's all I need now and I'm really anxious to run this bike!

    I tried bending the chain tensioner, but it isn't exact and it seems to cause the wheel to rub against it no matter how I bend it because it ends up slightly curved. I definitely want to make a spring tensioner with the parts from Harbor Freight.

    Lance- I agree completely and that is why this is frustrating. Hopefully the new sprocket/mount will solve the issue. I'm hoping it was just a bad sprocket, and mainly that it's not a problem with the wheel of some sort. It's a cheap coaster break hub, and I will NEVER buy a coaster break again. I wish there was an easy way to make it a non-coaster freewheel. I tried the 'fix' where you close the gap in the break, but it wasn't good at all.

    I drilled the tension mount into the frame with self tapping screws, so it won't go into the wheel again. The question now is can I get it bent/angled right? It is tricky because bending the mount changes the angle of the tension wheel too, so getting that wheel true and in good position without bending it so that it rubs and slows/stops is the challenge.
     
  8. GearNut

    GearNut Active Member


    You can make the coaster brake hub act like a freewheel hub just by removing the two brake shoes that are inside the hub. When comparing the operation to a traditional freewheel, you will have more free spin before it reengages when resuming pedaling after back pedalling, but it is not terrible.
     
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