Bicycle Mechanics - Chain use?
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Do any of you run a 10 speed chain on a 7 speed drive train? When the chain is on the 39 tooth ring and the 28 tooth gear the inside of the chain hits the front drailleur. I can't adjust the FD enough to remove or reduce the noise. Seems like I read a Sheldon Brown article where he suggested the use of a narrower chain to eliminate/reduce chain FD noise. The drive train is vintage Campy Chorus. Thanks in advance. Lp
You should be able to adjust the FD in farther. If you have too much tension on the cable it can keep the derailleur from adjusting inward.
With no tension on the derailleur cable the chain pins hit the inside of the FD housing. I,m not sure why. Lp
How are your limit screws set? Seems like you are forcing the FD too far out.
12-21-08, 06:59 PM
Limit screws are OK. Lp
"OK"...? Have you tried backing out the low limit screw all the way? If not, try it and see if you get the clearance you need.
I checked the low screw adjustment. Its out and allowing the max amount of travel toward the FD clamp. I am now considering if this is a bottom bracket or crankset issue. When I acquired this bike the original crankset and BB were not installed. The original owner gave me what he thought was the original Chorus crankset and BB which I installed. There were no issues with the generic crankset/BB. This adjustment issue has occured since installation of the oem parts. My question is; if this crankset were Athena or Record would the alignment of the chainrings be the same if they were all double setups? The chainline needs to move toward the chainrings to eliminate the contact with the FD. Thanks in advance ---- Lp
12-22-08, 04:45 PM
If your chainline is off, that could be another cause. Measure from the center of your downtube to the center of the crankset (between the rings for a double or to the middle ring for a triple). A double should be 43.5mm and a triple 45mm. It could be that your chainline is less than the applicable number and the derailler can't get out of the way.
Thanks I'll measure that when I get to the house. Lp
Best I can tell, dead on for 43.5 mm. No FD cable tension and the L screw is out allowing max travel toward the clamp. I must say I am perplexed. LP
12-23-08, 08:33 AM
Well, if it makes you feel any better, I had a similar situation on my LOOK KG386 frame trying to use a 105 9 speed front derailler. I would always get chain rub in the 30-27 combination because the frame got in the way of any more inward travel of the front derailler. The frame was basically my low stop and this was with a 10 speed chain. I am 100% positive that I was using the correct bottom bracket with my crank too (only one choice for an ISIS triple). I eventually switched to a 105 10 speed front derailler (for a different reason) and was pleasantly surprised that it cured the chain rub problem too.
Anyway, back to your problem, if you are using an old style 7 speed chain with proud rivets, a new style 6/7/8 speed chain with flush rivets might just fix the problem. If not, a 9 speed chain would give a little more and a 10 speed a bit more yet. Personally, I'd start with the 8 speed chain as they are dirt cheap (http://www.niagaracycle.com/product_info.php?products_id=20750) and then move on to a 9 speed if that doesn't work (http://www.niagaracycle.com/product_info.php?products_id=2431).
Issue has been resolved. Debri on the shift cable limited the low gear travel. Once I freed the cable I had all of the adjustment I required ---- and then some. All is as it should be. Many thanks. Lp
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