Chain rubbing on front derailleur when in biggest chainring

SpaceBadger

Hi

I had my bike serviced yesterday and everything is running really smoothly except that when I shifted into the biggest chainring I noticed the chain was now rubbing on the front derailleur.

I used to be able to move this about by twisting the cable end bits by the shifters (sorry, no idea what anything's called :oops: ) but now twisting that makes seemingly no difference to the position of the derailleur.

Is something broken? Or do I need to do something else to move the derailleur? I am crap at fettling so if there is anything I can do please explain it in ultimate numpty terms so I might have a crack at understanding!!

Cheers all
Spacebadger

bobones

The limit screws on the derailleur determine how far the cage will move in either direction. Cable tension will also affect the position of the cage within the bounds set by the limit screws. The angle and height of the derailleur will also have an effect on where chain rub takes place. It can be quite tricky to balance everything optimally if you're not used to fettling so my advice would be to take it back to the shop that serviced the bike and get them to readjust it, but it sounds to me that the limit screw may need tweaked if the barrel adjusters are having no effect. Have a look at the Park Tools site if you want to tackle it yourself.

nferrar

What cog(s) are you on at the back when it's rubbing and what gears are you using (do they have a trim function)?

SpaceBadger

Thanks for the replies.

It seems to be happening in all gear ratios provided I'm in the biggest ring at the front. I will check it out a bit more on the commute home. I'd love to answer the trim function question but honestly I have no idea! It's a Cannondale CAAD8 if that helps!

Thanks so much for the link, I will try to give it a go.