sstang13

So here's the story about my derailleur nice and quick:

I got my bike last July and pretty much since then, my shimano 105 set has been pretty bad, the gears at the back would never switch on the first click, and when they did on the second, the chain would jump a few cogs. Aside from that, my front gear would never switch into the big ring on the first click, id have to click twice and hold. The small ring was fine though.
I got my back gears fixed about 2 weeks ago and they worked phenomenally for about a week, then my chain fell off. I then brought my bike into a shop to a man who is basically a professional in cycling, no tour de France type stuff, but pro in about everything else and so I thought he'd do great job. My firs ride out with the bike after he fixed it completely, everything worked perfect and smooth. But my chain feel of again...
I've realized just yesterday that when I gear into the big ring at the front, it throws my chain over and falls off. So no more big ring for me, at least for now.

Anyway, I was just wondering what was causing this all to happen!? Could it be my gears, shimano 105 set,my bike in general, or just me? I am afraid to try and move the front derailleur over because I'm a huge newb at that stuff and just end up braking my bike when I even get near anything mechanical on it. If you were able to get this far, any feedback is appreciated, thanks!

Don in Austin

Run your high limit screw down.

Don in Austin

HillRider

He didn't "fix it completely", he didn't adjust the high limit screw properly.

sstang13

I actually forgot to mention that when I tried to fix it, no gear in the front would change, but he fixed it then. And I guess I'll try to screw the high limit screw down a bit, hopefully I don't have to go through all of that crap again. I feel like I could be doing soo much better on my rides if I didn't spend so much time screwing with my gears on my ride (or more better, the gears screwing with me).

AlphaDogg

By the way, it's a feature of 105 to require that double click to get into the big ring. It's called trim, and it works phenomenally for me on my 105 5700 equipped bike.

sstang13

Ya I know, but what happened here was there I guess I could say I had to push it over twice. Because no matter how many times I tried, everytime I pushed it over as far as I could, it wouldnt switch, I'd let it go, and then the second time I'd push and it'd work.

Homebrew01

As mentioned, the high limit screw needs to be turned in (clockwise) to prevent the derailleur from pushing the chain so far. I usually make these adjustments in 1/4 to 1/2 turn increments at a time. You can go to Park Tool's website for detailed repair info.

sstang13

Ya I've actually found out this morning while on a ride, its only when going fast. It worked perfectly for the whole ride, but at one point I was picking up on about 35km/hr and I switched to it and it fell off. Made me so mad. Aha anyway I know what's going on now I'm going to try the quarter/half turns and if nothing works I'll bring it into a shop.

hairnet

You also want to make sure that the FD is only a few mm above the big ring while the cable is loose and that it is perfectly inline with the chainring.

sstang13

I know for a fact that the FD is 2nm above the big ring, although I'll have to check for the loose cable and if it is perfectly inline (which I do not believe it is).

FBinNY 

Here's my take on component issues like the OP's.

75% are the mechanic's fault; poor set-up and adjustment. The fix is a different mechanic
20% are the owners fault; poor shift technique or other riding habits, and poor care, causing issues like bent hangers.
less than 5% (probably LT 1%) are mechanical issues relating to component overall quality and/or manufacturing defects which are extremely rare.

Obviously low end stuff isn't as good as high end stuff, but it does the basics like shifting through the range and keeping the chain on very well. Sometimes there's a mismatch in expectations for lower end and mid range hardware, but generally all stuff works better than you'd expect, if setup and adjusted correctly.

3rdcoast

Good info, thanks

Retro Grouch 

I could train a chimpanzee to adjust a rear derailleur (so long as the hanger was straight) but fronts can be something else.

Whenever a front derailleur doesn't respond to normal tuneing, my advice is to disconnect the shift cable and start over as if you were installing the derailleur from the very beginning. Park Tool, among others, has published a good set of step-by-step instructions for installing and adjusting front derailleurs. Start from the very beginning with the position of the derailleur on the seat tube because a good percentage of the time that's where the problem lies. Do all of the steps in order because each adjustment affects the subsequent adjustments.

It's possible your derailleur only needs a tweak of the high limit screw. I kind of doubt that, however, because you've already had it tuned by a fellow who you thought at the time was pretty competent. I'm thinking the angle of the derailleur relative to the seat tube is more likely a little off.