Shimano 105 Front Derailleur Problem

robert-sb

I have had my Cannondale with Shimano 105 groupset since March. The front derailleur changes onto the big chainring no problem but when I try and change back down to the small chainring it is very temperamental. On occasion it jumps back across but more often than not it won't and I have to try and give it a knock with my heel. Any ideas what could be causing this ?

Paul E

wind in the low limit screw so it moves more towards the frame, this will give it a bit more kick.

I had a problem where the chain was dropping off the large chain ring but not enough and would rest on the small chainring but not mesh into the teeth, one quarter of a turn to move it closer to the frame away form the chain and bingo

Monty Dog

It's probably either a 'sticky' cable or dirt build-up.
Spray from the front wheel causes muck to build up under the bottom bracket stopping the cable from releasing - give the cable a good clean and relube if necessary.
For the latter get yourself a toothbrush and some soapy water / bike cleaner and give the mech a good clean, getting rid of any trapped muck. Spray some WD40 or GT85 on the mech and manipulate it by hand if not springing freely.
Smacking it with your foot will proably knock it out of alignment, making matters worse.

robert-sb

Thanks both for the replies - will have a look tonight.

I figured that using my foot wasn't the best solution but I had tried simply spraying lube on it and when you are about to climb and need the small ring you don't have a lot of choice !