ammarolli

I have a new Trek Crossrip 2 with the new shimano tiagra 10speed drivetrain 34-50 in the front and 11-34 in the back.

I'm new to the road bike sifters and the trim function.
When I'm in the lowest gear small ring in the front and the biggest cog in the back I have a chain rub in the front derailleur but not when I use the trim function for the front derailleur.

Is this how the Shimano road gears are supposed to work?

headasunder

If you are having to use the trim function to move the derailleur towards the big chain ring (when in the small front big rear combo) to stop chain rub then your FD is not set up correctly take it back to the shop and get them to adjust it correctly, normally the trim function comes into play around the halfway mark on the rear cassette when in the small ring this varies a little bit depending on how its set up. There are plenty of instruction videos out there if you prefer to do your own work but considering its new a quick trip back to the seller would rectify it.

ammarolli

The bike is piratically a month old.
I did go the LBS but they did not do anything about maybe because I already used the trim.

cny-bikeman

No, the correct procedure for derailleur adjustment is to remove all the slack from the cable first, and any decent mechanic would know that. Take it back and explain the problem the same way as you did above. If necessary ask to have the bike put in the stand so the problem can be seen, and then check in the parking lot before you leave. Also, if the bike has not had a "30 day check" request that all adjustment and tightening be checked.

It's always a good idea to describe symptoms rather than conclusions or instructions, because if you do the latter it may misdirect the mechanic or encourage shortsighted adjustments.

ammarolli

I'll go to the LBS thanks for the help.

alcjphil

The one thing that you don't include is which side of the front derailleur that the rub occurs on and how you trim the derailleur to fix the problem. If the rub occurs on the inside of the cage and you trim by using the inside lever to trim it, your adjustment is as it should be.

fietsbob

The way the engineers designed the cages of STI FD, they should clear the chain unless you use 'cross chain' combinations.

Avoid the Big-big and Small-small combinations.. ?

alcjphil

The OP wasn't asking about chain rub in a cross chain situation

fietsbob

I am not there, its not in front of me , Another required blind guess..


I use friction shifters on my own bikes , it only rubs until I re center the cage.

With my hand on the Lever..

fietsbob

resolution to guessing, here, has been chosen, Good..