Chain rubbing

bad_moose

I've been riding on and off for a couple of years now but I really got back into it at the start of the year. Had my Felt Z100 stolen and bought a new Giant Defy 5 to replace it. Now the Giant is a really good bike and I'm loving riding it, but the chain has an annoying habit of rubbing on the front derailleur. I've sat down for hours and tried to adjust it, but whatever I do it rubs. If I adjust it so it doesn't rub in the bigger gears, it rubs as soon as I change down to the smaller ones, and if I then adjust it so that it doesn't rub on them, it rubs on the bigger ones again as soon as I change up. It's really frustrating because the rest of the bike is perfect, it's dead silent until this chain rubbing starts. :x

What's the issue? I'm fairly sure it's not that I'm crap at adjusting the cable because I'm perfectly able to do it on my run-around bike and the rest of my families bikes. Is it the actual angle of the derailleur on the frame? Do I just need to rotate it a bit so it's more in line with the chain? Any help appreciated, thanks!

andrewjoseph

Do your shifters have a trim function?

bad_moose

Err I'm not too sure. How would I go about checking if they do?

chaymck

Does it rub when you are cross chaining? I.e chain on large on the front and back? Or small-small?

trooperk

A trim function is the front shifter has 2 positions ( 2 clicks) before it drops the chain on to the smaller ring, so you can choose where you want the chain depending what gear you in at the back wheel.
If the bikes is new allow time for cable stretch as I’m having to adjust my every day.
Also read this.http://techdocs.shimano.com/media/techdocs/content/cycle/SI/TIAGRA/FD-4500/SI_5K70A_En_v1_m56577569830606969.pdf

TommyB61

I had a similar problem which I fixed yesterday using the Park Tools website. Might work for you:

http://www.parktool.com/blog/repair-help/front-derailleur-adjustments

hairy_boy

When adjusting the front derailleur make sure you are setting things up based on not cross chaining.

As a rough rule of thumb:

When on the large front ring you should be using the smaller 7 (out of 9) cogs on the back.

When on the small front ring you should be using the larger 7 (out of 9) cogs on the back.

After setting up correctly if you get any chain rubbing on the front derailleur its telling you that you are in the wrong combination of gears !

I have found it nigh on impossible with any of my road or mtb bikes to adjust so you get no front derailleur chain rubbing in cross chaining large-large and small-small gear combinations - the gears are simply not designed to be used in those combos.

bad_moose

Hey guys!

Definitely not cable stretch because the bike isn't that new. I realised that the shifters do have a trim function and that has consequently solved my issue. A friend also told me (and also as some of you have said) that it was much better for the bike if you just drop down to the smaller chainring and then change gears on the back to achieve the 'same' gear without pulling the chain into a nasty shape and causing it to rub. Thanks very much all!