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difficulty with front derailleur adjustment
Posted: 23 May 2015, 9:17pm
by Vitara
I'm having problems trying to adjust my front derailleur. It's 10 speed tiagra, was running fine. Recently changed the change and cassette and ridden 500 miles with no problems. After a 3 day trip last weekend, which included riding along a sandy promenade (not sure if this is significant) I started getting some chain rubbing. Have given everything a good clean, and attempted adjustment today which didn't help, so went through full FD setup and adjustment using my Haynes manual. Problem now seems even worse. Chain rubs against the mech at either end of the gear range; i.e. small front big back and big front small back.
No sure if I'm doing something wrong or have missed something. Also wondering if worn chain rings &/or stretched cable might be a factor.
Re: difficulty with front derailleur adjustment
Posted: 23 May 2015, 9:38pm
by MikeF
Vitara wrote:Chain rubs against the mech at either end of the gear range; i.e. small front big back and big front small back.
So is it rubbing on the outer side of the cage with the big chainring and the inner side of the cage on the small ring or what? Has the clamp twisted on the seat tube ie is the cage parallel to the chainrings?
Re: difficulty with front derailleur adjustment
Posted: 23 May 2015, 9:52pm
by Vitara
Mick, I think you may have nailed it. Although it looks parrallel I did transport the bike in the back of an estate car with a second bike after our weekend & I guess it would only need to have twisted a small amount anticlockwise to cause the problems I'm getting. Will head out to the garage in a minute and take another look.
Re: difficulty with front derailleur adjustment
Posted: 24 May 2015, 7:33pm
by recordacefromnew
Vitara wrote:Chain rubs against the mech at either end of the gear range; i.e. small front big back and big front small back.
Twisting the front mech would likely manifest just one, not both the above phenomena.
If I were you I would check:
1) mech is parallel to large ring when viewed from top, and outer cage clearing large ring by no more than 2mm when viewed from side.
2) inner cage clearing chain by no more than 1mm when chain is on small front large back, if less either the cable tension is too high or the L limit screw needs to be turned anticlockwise or both - to avoid cable tension being wrong set L limit screw to achieve the 1mm clearance with the cable slack, then take up cable slack by increasing cable tension so that the adjuster can JUST start to move the mech
3) cage clearing chain by no more than 1mm when chain is on large front small back, if less (given cable tension should be correct after step 2) H limit screw needs to be turned anticlockwise