Chain tube issues.

My rambler GT has about 500 miles and the top chain guide tube has worn through. The chain is now eating the bottom of the seat frame and the seat bolt. Anyone else having trouble? Looks like the force of pedaling is pulling the tube up against the seat bottom. When slack it drops about a quarter inch. Time to go back to idlers I guess.

Comments

  • Wow!  I've never heard of that happening. Sounds like someone missed adding the little connectors that keep it near the boom.  I have two on the top and one on the bottom on my Rover under the seat and they used a cable tie to connect it to the cross bar in the front.
  • Aha! It just has one locator near the back.
  • I think it is a combo of the missing locator and that on the bottom of the seat bracket the doubler has a point that causes a pressure point as the tube moves up...under pedaling stress. Now I need a new tube and to modify the seat frame a bit.
  • Can I get a picture of your tube routing and clamps?
  • Go to the videos and find "Assembling your Rambler part 4 of 5" at about 3:40 it begins the instructions for mounting the tube.
  • Did you see what you needed in the video?
  • I'm not really able to visualize the damage from your description. Can you loosen the tube clamp and rotate (twist) the tube 180 degrees, putting the damaged area down?  That may work in the short term, while being an easy enough fix that won't require breaking the chain.

    If that doesn't work, try removing and flipping the tube, making the end that was facing the front point to the rear instead. That should move the damaged area away from the pressure point.

    I agree with jamesr about t-cycle, their chain tubes are very inexpensive. You can get 2ft with flared ends for less than $10.

    Something else that may help is if you can move the seat back and bring in the boom. That will lower the front crankset a little.

    That said, there's definitely something wrong with your setup. This shouldn't have happened at all, let alone in only 500 miles. The edges on the tubes on my rover are only slightly buzzed, and I have at least 4 times that mileage. I'm not quite sure what you mean by doubler, are you talking about the seat frame tubing that comes down and goes into the seat bracket? 

    I'd also strongly suggest checking the chain for burrs or sharp points that may be shredding things.

    I'd check out the videos and compare them to your trike to make sure nothing is seriously out of wack. Part 5, at ~10 minutes and 20 sec in, has a good close up of the seat clamp area.

    - PaulNM


  • I have a similar problem. When on the large chainring and pushing hard, there is an angle bracket on the bottom of the seat frame that is directly in the chain path. My temporary solution is a 3 x 3/4 x 1/4 inch piece of wood ziptied between the seat frame boss and the chain tube. It keeps that V made by that bracket from cutting through the tube as the chain slaps up there. Ultimately I'll put an idler near there.
  • edited September 1
    swpaskett wrote: »
    ... It keeps that V made by that bracket from cutting through the tube as the chain slaps up there. ...

    Chain slap means the chain is too loose. Loosen the rear wheel nuts, pull the wheel backwards until the chain is taunt, then tighten the wheel bolts uniformly & snug.

  • I pulled the boom out on mine as was suggested here. Did it to my wife's
    Rover as well. Axle is all the way forward in dropout. We have internal
    hubs.
  • chainslap is normal occurrence with a derailleur driveline whenever shifting, more pronounced switching rings on the front derailleur - tis why chainkeepers are mounted on powerside idlers. a properly mounted section of chaintube is better than a keeper for limiting chain ripple.

    ripple also happens with slack chain with an igh - unsmooth pedal strokes can cause the chain to hop the rear wheel sprocket, wear down the teeth as well. a tube will limit the ripple on a too loose chain and help compensate for axle-slip as well as protect the frame from being sawed by the chain.

    axle all the way forward into the dropout solves axle-slip as well as keeping the rear wheel aligned with the frame.
  • Well, you guys make me sorry I used the term "slap." This is not a chainslap issue, it is interference with the normal chainpath caused by a portion of the seat mounting bracket. TT has a solution that costs about $10 and consists of a short arm and a chain tube clamp. The arm screws onto the seat clamp and the clamp attaches to the other end of the arm, holding the chain tube below the seat bracket. If you have the same trouble, order a "chain tube bracket arm" and a chain tube clamp. End of story. This appears to be standard on the Traveler and should be on Rambler, too, IMO. But for $10 I'm not really up for that fight.
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