steps in installing front derailleur

[mattjf]

I had a few problems with my front derailleur, a Shimano Sora on a rode bike, which lead me to take it off. I now need to install it back on, but am having problems. This is my first road bike and I am just learning how to do repairs.

I have clamped it back on the bike and measured the height off the largest chainring. The outer part of the cage is also parallel to the large chainring. The problem I am having is I cannot get it to shift in all gears without it rubbing on the cage. For instance, if I get it set where it works on the outside chainring, if I shift to the smallest chaingring, it will rub on the cage. It's also possible the cable tension is incorrect. In what order should I set things? For instance: make cable reasonably tight, set low limit screw, set high limit screw, adjust cable tension. Would this be the correct order, or some other way? Any tips you could provide would be appreciated.

-Matt

 

[fish156]

I had a few problems with my front derailleur, a Shimano Sora on a rode bike, which lead me to take it off. I now need to install it back on, but am having problems. This is my first road bike and I am just learning how to do repairs.

I have clamped it back on the bike and measured the height off the largest chainring. The outer part of the cage is also parallel to the large chainring. The problem I am having is I cannot get it to shift in all gears without it rubbing on the cage. For instance, if I get it set where it works on the outside chainring, if I shift to the smallest chaingring, it will rub on the cage. It's also possible the cable tension is incorrect. In what order should I set things? For instance: make cable reasonably tight, set low limit screw, set high limit screw, adjust cable tension. Would this be the correct order, or some other way? Any tips you could provide would be appreciated.

-Matt

I have found that with Shimano FDs your best bet is to follow the Shimano tech documents as closely as you can. Here is the doc for a Sora triple FD:

http://bike.shimano.com/media/cycling/techdocs/en/bikecomponents/FD/SI-5E90C_v2_m56577569830563107.pdf

Take your time and read everything. It's very easy to skip over some small instruction and that can ruin the adjustment. Shimano is very thrifty with it's wording.

With most derailleurs today you are going to have a crosschaining/rubbing problem in some gear situation - especially in the (small chainring & smallest sprockets) situation. There is no way to fix this - just don't ride in those combinations. That is specifically why Shimano talks about this in the "Note" at the beginning of the proceedure.

 

[mattjf]

Thank you very much for your response. I'll read this tomorrow. It's probably much better looking at Shimano's specific documentation rather than the general documentation found in my bike repair book.

-Matt

 

[boudreaux]

Thank you very much for your response. I'll read this tomorrow. It's probably much better looking at Shimano's specific documentation rather than the general documentation found in my bike repair book.

-Matt

The basics of derailer adjustment ae the same regardless of source. www.parktool.com repair sction also has a good drill. Front shifters also have trim to take care of chain rub. Big hint: You start the adjustment with the shifter in small chainring position,cable loose chain on small ring,and big cog,low limit set so there is .5-1mm clearance between inner cage and chain. If you don't do adjustments in proper sequence you are just wasting your time.