08-30-2010, 07:46 AM
It seems like I can spend hours working the front shifter trim control and still not completely avoid chain rubbing problems. Specifically, my issue seems to be with the middle chainring.
Here's a quick rundown of my drivetrain:
Chainwheels -- SR Suntour XCT-V2, 48/38/28T
Front derailleur -- Shimano FD-C051
Rear freewhee; -- Shimano MF-TZ31, 14/16/18/20/22/24/34T 7-speed
Rear derailleur -- Shimano RD-M310
I know to avoid small chainring/small sprocket combinations such as 1/5, 1/6, 1/7, and large/large combinations such as 3/1, 3/2, and 3/3. That's not an issue. I would like to be able to use all rear sprockets with the middle chainring, but no matter where I set the trim, it seems I'm always getting a rub on one side or the other.
I can trim it outward enough so that 2/7 doesn't rub, but then 2/1 will definitely rub, and usually so does 2/2. If I then move the trim control the other way, just enough to stop 2/2 from rubbing, 2/7 seems to cause a rub. I'm not so worried about 2/1, as my 2/1 and 1/2 gear ratios are reasonably close and I probably should hit the granny chainring if 2/2 isn't enough to climb, but I'm annoyed that I can't seem to get the whole range from 2/2 to 2/7 without the chain rubbing the front derailleur somewhere.
Since trimming and cable adjustments don't seem to be helping this, do you all suppose it could be a position issue (derailleur height/angle)? It doesn't look that bad, honestly; I can say for sure that the cage clears the large chainring by probably 2-3mm, and the angle looks like it's parallel to the frame.
Or would I be better off with a front derailleur with a wider cage?
Here's a quick rundown of my drivetrain:
Chainwheels -- SR Suntour XCT-V2, 48/38/28T
Front derailleur -- Shimano FD-C051
Rear freewhee; -- Shimano MF-TZ31, 14/16/18/20/22/24/34T 7-speed
Rear derailleur -- Shimano RD-M310
I know to avoid small chainring/small sprocket combinations such as 1/5, 1/6, 1/7, and large/large combinations such as 3/1, 3/2, and 3/3. That's not an issue. I would like to be able to use all rear sprockets with the middle chainring, but no matter where I set the trim, it seems I'm always getting a rub on one side or the other.
I can trim it outward enough so that 2/7 doesn't rub, but then 2/1 will definitely rub, and usually so does 2/2. If I then move the trim control the other way, just enough to stop 2/2 from rubbing, 2/7 seems to cause a rub. I'm not so worried about 2/1, as my 2/1 and 1/2 gear ratios are reasonably close and I probably should hit the granny chainring if 2/2 isn't enough to climb, but I'm annoyed that I can't seem to get the whole range from 2/2 to 2/7 without the chain rubbing the front derailleur somewhere.
Since trimming and cable adjustments don't seem to be helping this, do you all suppose it could be a position issue (derailleur height/angle)? It doesn't look that bad, honestly; I can say for sure that the cage clears the large chainring by probably 2-3mm, and the angle looks like it's parallel to the frame.
Or would I be better off with a front derailleur with a wider cage?