Chattery noise advice please

[screenman]

Sometimes when in the big/big cog combination the chain will rub the front mech causing a chattering (I know its a no no but in the real world this combo does get used), on 105 and above there is a trim facility that moves the front mech inboard by about 3mm to reduce/stop this from happening?

I must live in the real world then, as I never ride big big or the other way around, why would you?

 

[fossyant]

There is a big overlap of gears, especially if you are running dinner plate sprockets. Don't use the last 2 or 3 gears. It's not good for the chain for a start, and can start to shift. If I 'try' and use 7 and 8 (on my 8 Speed Dura Ace stuff) the shifting pins on the big ring will try and upshift the chain to the big ring - you can hear them catch due to the angle of the chain (running 53T so the chain ring is bigger). Same happens on my MTB. You can get away with it if you don't have the shift pins and ramps.

Best get into shifting to the bigger chain ring earlier