Front mech help needed

1964johnr

I purchased a Ribble Granfondo online with shimano 105 set up. Pleased with the bike accept for front mech chain rub issue. I have a compact chain ring set up and can use gears 1 through to six on the big ring with no chain rub issues, but it rubs on gears 7 to 10. On the small ring the chain rubs on the front mech on gears 1 through to 4. When I switch from the big ring to the small ring, when I take it back to the big ring I always get chain rub on the front mech until I fiddle with the barrel adjuster while riding along. I would like some help from someone who can tell me what to do to adjust the front mech so that I can use most of the gears on both rings without getting front mech chain rub. Thanks.

dj58

Are you using the trim function?

Download a copy of the Shimano Dealer Manual DM-GN0001-08 from here http://si.shimano.com/ Go to page 25 and follow the installation and setup instructions.

Take a look at this

http://roadcyclinguk.com/how-to/mainten ... lleur.html

http://www.youtube.com/watch?v=42_tKpE6PhI

Undertones

Bikeradar has a Youtube video on it which I found helpful.

https://www.youtube.com/watch?v=Q-uANcaVBfI

chris_bass

The trim mentioned above shoud help, although probably not for that many gears. If you push the left shifter slightly it will click once, this won't shift the chain to the big chain ring but will adjust the front mech slightly allowing more room for the chain. The same happens if you click the left mech gently it will drop the front mech in slightly.

Cross chaining isn't usually a good idea though but each to their own.

Jules Winnfield

I think I read on here once that just because your bike has 20 gears, it doesn't mean you can use all 20 gears.

morstar

It's also possible you may need to adjust the limit screws. The gearing combinations you describe do mean this is a possibility that the derailleur isn't able to move across far enough to stop chain rub no matter how much trimming you do.

chris_bass

Jules Winnfield wrote:

I think I read on here once that just because your bike has 20 gears, it doesn't mean you can use all 20 gears.

think of it like a guitar, just because you have 6 strings and 24 frets, doesnt mean you have 144 different notes, most can be found in numerous places down the fretboard.

If you are in the big big combination of gears that gearing (or very near to it) can be found elsewhere and won't put sideways forces on the chain.

Dippydog3

What make and model are the derailleurs?

Just read the OP. 105.
Today I set up a 105/Tiagra ten speed with an 11-34 cassette. No chain rub on either end of the scale.

I found it more logical to move the shifter by hand and then wind the limit screw to hold that maximum position that you want, i.e just not touching the chain. I did that for the upper limit (outer screw) on big ring, small cog. For the inner limit screw (small ring, big cog), turning the screw moves the shifter to the just not touching position.

You should be able to set it up so that all the gears are useable. Anything more than very slight "ticking" of the than at the extreme limits, say the last two cogs, is a sign of bad setup.

simon_masterson

Jules Winnfield wrote:

I think I read on here once that just because your bike has 20 gears, it doesn't mean you can use all 20 gears.

Indeed. On older transmissions with fewer sprockets you can get away with it a bit more, and the chains are stouter anyway, but even then some combinations will rub.

With all of this said though, chains wear out anyway, and 50x28 is a nice gear to climb with. As long as you don't do it all the time, I don't think it need be a huge issue.

simon_masterson

Jules Winnfield wrote:

I think I read on here once that just because your bike has 20 gears, it doesn't mean you can use all 20 gears.

Indeed. On older transmissions with fewer sprockets you can get away with it a bit more, and the chains are stouter anyway, but even then some combinations will rub.

With all of this said though, chains wear out anyway, and 50x28 is a nice gear to climb with. As long as you don't do it all the time, I don't think it need be a huge issue.

Dippydog3

Simon Masterson wrote:

Jules Winnfield wrote:

I think I read on here once that just because your bike has 20 gears, it doesn't mean you can use all 20 gears.

Indeed. On older transmissions with fewer sprockets you can get away with it a bit more, and the chains are stouter anyway, but even then some combinations will rub.

With all of this said though, chains wear out anyway, and 50x28 is a nice gear to climb with. As long as you don't do it all the time, I don't think it need be a huge issue.

you can say that again.