Chain rub on front derailleur - both sides?!!

smudge002

I have just taken delivery of a new road bike and I am having a couple of teething issues. I've only ridden about 60 miles so far but there are some gearing issues. First, I noticed that the rear indexing was way off (I couldn't shift onto the largest sprocket) - fairly easily sorted with the barrel adjuster at the rear derailleur.

However, the front derailleur is a different story; on the large chainring the chain is rubbing against the cage on the outside when on the smallest cogs, and then rubbing on the inside when on the largest couple of cogs. Does anyone have any idea why this might be and how to fix it? Playing with the limit screws doesn't seem right.

BTW - the bike is a very nice Giant Propel but because it was an insurance replacement I couldn't buy it from my LBS and had to via their preferred online supplier, and therefore it's not just a case of taking it back and asking them to sort it.

Many thanks in advance!

wongataa

You have two options.
1. Take it to a bkie shop to fix.
2. This is the best really. Download the instructions for your gears from the internet site of the manufacturer. Read them. Look at online videos showing how to set up gears. Disconnect the gear cable from the offending shifter and start setting them up from scratch. This way you will learn how they work, how to adjust them, and what may be wrong if there is an issue in the future. Setting up gears is not hard to learn.

Note: even when set up properly and with correct use of any trimming function you may still get chain rub when running very cross chained.

dgunthor

rear gears needing asjusting after a few rides == normal

front mech - are you using the trim function? i'd expect some rubbing without using the trim.
put the chain on the small chainring - is the cable loose? use the barrel adjuster to tighten it a little

trailflow

Watch this video
https://www.youtube.com/watch?v=hlbenKUx9JM

smudge002

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19653800#p19653800]wongataa[/url] wrote:

2. This is the best really. Download the instructions for your gears from the internet site of the manufacturer. Read them. Look at online videos showing how to set up gears. Disconnect the gear cable from the offending shifter and start setting them up from scratch. This way you will learn how they work, how to adjust them, and what may be wrong if there is an issue in the future. Setting up gears is not hard to learn.

Note: even when set up properly and with correct use of any trimming function you may still get chain rub when running very cross chained.

Thanks - I will download and have a read. It's Shimano 105 BTW.

I'm still not sure on the trimming function; am I correct in thinking that you may have to use a small further adjustment on the shifters to get correct alignment? I'm not sure I ever had to do that on my previous bike at all (and in fact I don't think I had chain rub even when cross chaining at a maximum i.e. large/large)

dgunthor

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19653834#p19653834]smudge002[/url] wrote:

I'm still not sure on the trimming function; am I correct in thinking that you may have to use a small further adjustment on the shifters to get correct alignment? I'm not sure I ever had to do that on my previous bike at all (and in fact I don't think I had chain rub even when cross chaining at a maximum i.e. large/large)

trim - in small ring, move the front shifter a little and the mech will move over a bit (trim) so no chain rub when using the smallest cassette sprockets.

for large chainring there should be an extra shift available (trim) to move the mech cage a little further out, again for use with smallest sprockets. first click down on front mech will remove the trim