Bicycle Mechanics - Front Derailleur Set Up

I have can never propertly set up my front derailleur. I can adjust the limiting screws fine, but whenever I shift to the big chainring, the derailleur always resets back to small one. I can't figure it out. I had this problem on my old downtube shifter bike, and now on with STI. Is it a cable tension thing? I just don't get it. I guess this is why all my bikes end up fixed or single speed. I figure I am missing something very simple and any suggestions will be greatly appreciated. Thanks.

I have can never propertly set up my front derailleur. I can adjust the limiting screws fine, but whenever I shift to the big chainring, the derailleur always resets back to small one. I can't figure it out. I had this problem on my old downtube shifter bike, and now on with STI. Is it a cable tension thing? I just don't get it. I guess this is why all my bikes end up fixed or single speed. I figure I am missing something very simple and any suggestions will be greatly appreciated. Thanks.
Park Tools has an excellent site that explains things in common, easy to understand terms. Here's the section on front dérailleurs: http://www.parktool.com/repair_help/howfix_frontderailleur.shtml

you are not the only one- I think that the front der is the hardest thing to adjust right. I once had the same experience with a deore front der and had to admit defeat in the end and take the bike to the bike shop. I had tried all cable tensions and followed the Park tools directions and still could not shift the chain to the largest chain wheel. The mechanic did some adjusting and had to bend the cage to get the shift to work.

you are not the only one- I think that the front der is the hardest thing to adjust right. I once had the same experience with a deore front der and had to admit defeat in the end and take the bike to the bike shop. I had tried all cable tensions and followed the Park tools directions and still could not shift the chain to the largest chain wheel. The mechanic did some adjusting and had to bend the cage to get the shift to work.

I agree that it is hard to adjust. It is especially hard when you are dealing with a design flaw. I have a 04 Trek 4300 and the front derailler is horrible. I can't get enough travel out of it to allow me to run the extreme innermost or the extreme outermost combinations. IOW, I can adjust it up to not get chain rub on the smallest chain ring and the largest cog but then i have rub on the outermost. (largest chainring and smallest cog.

The problem is that the derailler rests on the seat tube when you try and adjust the screw to the setting where it needs to be to allow for proper operation. IOW, it needs to be able to travel inward more but can't because of the seat tube.

My LBS guys told me that is just the design of the thing. That really sucks cuz I have the 03 version of the same bike and it's front Der. works fine. I can't see a visual difference between the bikes but apparently there is. Oh well...................

I have can never propertly set up my front derailleur. I can adjust the limiting screws fine, but whenever I shift to the big chainring, the derailleur always resets back to small one. I can't figure it out. I had this problem on my old downtube shifter bike, and now on with STI. Is it a cable tension thing? I just don't get it. I guess this is why all my bikes end up fixed or single speed. I figure I am missing something very simple and any suggestions will be greatly appreciated. Thanks.

The Barnett's manuals at the top of this Forum are very good...a great free resource, IMO. If you start at the beginning and follow the procedure all the way through, you should have success. If that doesn't work for you, take it to a mechanic....no point in struggling with poor shifting with STI.

I was baffled by the front der. as well till my LBS explained to me that it is all about doing it in the right sequence. Download the manual and follow the sequence exactly. You will be amazed at how easy it is..... :)

I went for a ride today and the front der. shifted alright. It needs some serious adjusting though. I had it running fine for a few hundred miles after the initial build up, but some fine tuning on the stand through it out of whack. I've decided that the next day too nasty to ride will be a maintenance day and I take apart and rebuild the front drivetrain. Thanks for all of the tips.

I found Simano's adjusting instructions to be the most helpful. Barnett goes way overboard. A lot of Barnett is unnecessary.

1) adjust front der. height so the outer cage clears the big ring by 1-2mm
2) shift into biggest cog in rear, smallest in front
3) loosen cable clamp bolt
4) turn front der. adjusting barrel all the way in, back out two turns
5) adjust low limit screw so inner plate is 1-2mm inside of chain
6) pull cable taut, secure clamp bolt
7) shift to smallest cog in rear, try to shift up to big ring in front
8) rubbing? back out adjusting barrel 1/2 turn.
9) check clearance between outer der. plate & chain, should be 1-2mm. more than that? turn in the high limit screw.
10) try to shift back down to the small ring. if it hesitates, back out the low limit a little and try again.

running an indexed triple?

1) after the above, goto the middle ring. shift up to the biggest cog in back. if the chain is rubbing on the inner plate, turn in the barrel adjuster 1/4 turn or so.
2) shift down to the smallest cog in back. if that's rubbing, turn out the barrel adjusted 1/4 turn or so
3) if they both rub, try to find a happy middleground.


it needs to be able to travel inward more but can't because of the seat tube.

there's an odd chance your bottom bracket spindle may be too short. moving to a slightly longer one may rectify that without altering your chainline too much. then again, your chainline could already be off, and moving to the longer spindle would fix that as well. two birds with one stone style.

fore has it correct. Looks like the Shimano instructions. Most important - for the first time - instructions 1-5 of the above. After that any further adj can be made with only the barrells

Fore,
Thanks for your instructions. I bought a brand new bike with Ultegra from the local Supergo store. Initially, I had chainrub in the small front to the 4 outside gears in back, large front to the 3 inside gears in back and middle front to the extreme inside and outside gears in back. That's nine unusabel gears!! With some tweaking of the barrel adjuster and limit screws, I was able to use four of those gears. Then I brought it back for my 30 day adjustment...they messed it all up again. Frustrated with the shop, I started from scratch using Fore's instructions. With a lot of patience, I am now able to use all of the gears except the small front to 3 outside gears in back. I'm OK with that because if I need those gears, I'll just shift to the middle ring. The FD is all about compromise. I'm happy as a clam.

At the very least, you should never use the small ring and the outside cog, or the large ring and the inside cog. Opinions and "expert advice" vary on what other oblique combinations you shouldn't use. This has nothing to do, however, with derailleur cage rub, but if you follow it, you won't need to obsess so much about adjusting the front cage for combinations that it's otherwise unwise to use anyway.