Bit of a noob!

[kevinsmbuk]

I have just bought a Canyon AL 6 and it's fitted with shimano 105 all round, I have been having issues with the front derailleur.

I have adjusted the rear derailleur then my setup for the front derailleur was as follows:

1. put into largest cog on rear and smallest cog on front and adjust low screw.
2. put into smallest cog on rear and largest cog on front and adjust high screw.
3. lock cable into position.

But what happens is it shifts without rubbing on the largest cog on the front derailleur all the way through the rear gears, but when it's put onto the smaller cog on the front derailleur it goes through gears 1,2,3,4,5,6 without scraping the front derailleur as soon as I shift into gear 7 it rubs then gets worse on 8,9,10.

What am I doing wrong?

[Joe_W]

1) you shouldn't run the extreme combinations anyway
2) the setup is tricky, indeed. It has to be dialed in so that it _just_ does not rub... took me some tries to get this right.

[kevinsmbuk]

1, agreed I would expect that the 10th gear should rub slightly?

2, tell me about it! what should I be adjusting just the barrell knobs or the screws or both?

[Joe_W]

I found that it was an iterative process. I first adjusted the limit screws, then the cable tension of the FD to move the trim step to the correct position. Then, re-checked and adjusted (mainly) the high limit screw. Repeat ad nauseam...
Good luck! It takes some patience, but it is not too bad once you really figure out which adjustment influences the others in what way...

[cny-man]

(06-28-2012, 11:38 AM)kevinsmbuk Wrote:  1, agreed I would expect that the 10th gear should rub slightly?

2, tell me about it! what should I be adjusting just the barrell knobs or the screws or both?

Do not adjust either. If the bike is shifting OK at the extremes and between chainwheels it is correctly adjusted.

The front derailleur cage can only be so wide and still shift well, so at some point the chain is going to rub as you move across the rear. When it does you just move the front out slightly (trim). That is normal and there is no way to avoid doing so.

However, you should not ride in all possible combinations, even if you can without rubbing. It is very hard on the drive train and there is overlap between the gear ranges anyway. The small front with the two smallest rear cogs should not be ridden at all. Lots of info if you just Google “How to shift a bicycle.”