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Old 01-10-11, 12:04 PM   #1
dogbitteneear
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chain keeps coming off front gear ring

I need some info on how to correct this problem.

I have a long wheel based recumbent(tour easy clone). this problem is of a recent
origin. The chain when its lon the large ring slips off to the ring guard.

My question is:

1. Is the chain stretched or

2. Is the chain being twisted by its length( It is a total of 2 1/2 chains).

any help would be appreciated.
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Old 01-10-11, 01:16 PM   #2
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I am not very knowledgeable on recumbents, but it sounds like it is probably a front derailleur problem - if the derailleur is in alignment, the chain should not be falling off the large ring under normal riding conditions. Front derailleurs can be really tricky to adjust if you're not familiar with it, but it basically comes down to the limit screw (which limits how far out the cage can go), the clamp height of the deralleur, and the angle in relation to the rings. Bring it down to a shop, or check out http://www.parktool.com/blog/repair-...ur-adjustments for some hints on how to adjust.

(The FD might not be the issue - again, I am not very familiar with recumbents. However, it does sound like what the problem is).
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Old 01-10-11, 01:46 PM   #3
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First look for a bent tooth on the big ring.

If the chain falls to the outside, it would help to slightly bevel the left side of the chainring's teeth.
To do this, hold a file against the tips of the ring at a ~45-degree angle while rotating the cranks backward.
I've solved many a chain-throw problem on unusual setups using this method, even using a rock (as a file) when I needed to fix the problem while out riding. It's quick and easy to adjust the tooth profile enough to encourage the chain to go to one side of the teeth or the other.

I am assuming that normal adjustments have been performed already. One thing often overlooked is the foreward-pointing tab on the outer cage plate of the front derailer. Especially on older models, this should be bent in as far as clearance allows in order to control any tendency to overshift to the outside of the big ring. The derailer must first be set to the right height, typicallt about 2mm above the tips of the teeth when in the big ring.
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Old 01-10-11, 03:40 PM   #4
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P.S. I forgot to mention that I did change out the front gearring. that may have something to do with that.
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Old 01-10-11, 04:20 PM   #5
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Quote:
Originally Posted by dogbitteneear View Post
P.S. I forgot to mention that I did change out the front gearring. that may have something to do with that.
Are there the same amount of teeth? If not, they will change the derailleur height in comparison to the ring and screw with the alignment...
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Old 01-11-11, 02:30 AM   #6
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The ring guard should be preventing this from happening. If you've changed to a different size chainring, then maybe the ring guard needs to be changed to match, or it may be possible to modify the current ring guard in some way so that it does it's job better (after checking the FD adjustment, as mentioned above).
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Old 01-11-11, 01:47 PM   #7
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Quote:
Originally Posted by Chris_W View Post
The ring guard should be preventing this from happening. If you've changed to a different size chainring, then maybe the ring guard needs to be changed to match, or it may be possible to modify the current ring guard in some way so that it does it's job better (after checking the FD adjustment, as mentioned above).
Read.

He said slips off TO the chainguard, not slips off it. This is a front derailleur high limit screw adjustment problem.
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