Lost gear combinations

[IzzyG]

Heya guys, looking for some help. Here's the situation. My bike was shifting fine and could use the small front chainring/second smallest rear cog or large front chainring/second largest rear cog without scraping the front derailleur. It only scrapes the front derailleur when I'm using the largest front/smallest back or smallest front/largest back combinations. However, for some reason, my front shifting stopped working. Would not shifting, and I brought it to the LBS. They said the front derailleur got misaligned. No idea how that happened but they did a tune up and reallignment.

Now, the front shifts very smoothly. However, the chain scraps the front derailleur when the small front/third largest back or large front/third smallest back combinations. I actually lost 4 gear combinations! Is this normal? Should I bring it back to the LBS and inform them of the "problem"? Thanks in advance.

Izzy G.

 

[rek]

When you're talking about "largest" and "smallest" in terms of your gears, are you talking in terms of speed, or the number of teeth in the respective cog/chainring?

If it's number of teeth you're talking about, they may have set the limit screws for the front derailleur a little tight, so when the chain is bent in the more "off to one side" gears, it starts rattling against the front derailleur cage.

On each extremity, try loosening the HIGH or LOW limit screws (depending on which chainring you're adjusting at the time) a quarter-turn a time and give it a go, see if it frees up the other gear combinations. Don't adjust it too much though, or else you increase the risk of the chain falling off the front chainrings during a shift.

As a backgrounder to what all this is doing, read http://www.parktool.com/repair/readhowto.asp?id=75 (under "Front Derailleur Limit Screw Settings")

 

[Retro Grouch]

I'd take it back.

There is a whole sequence of adjustments for front derailleurs. Often, to get one working right you have to start at the beginning and go through the whole process. When they said that your derailleur was "misaligned" I suspect that's what they did.

Unfortunately, if you don't get the derailleur aligned properly on the seat tube right at the start, nothing that you do afteward, like fooling with the limit screws or cable tension, is likely to get it to work properly. I suspect that might be the case too.

In any event, you paid to have your front derailleur properly adjusted and you didn't get that yet. It should work as well as it did before the derailleur was "misaligned".

 

[dhk]

Retro Grouch said it all here. The bike should be shifting perfectly when you picked it up at the LBS. You shouldn't have to tinker with any screws or adjustments after paying for a pro to do the work.

Have to ask a simple question though: Is the trim function on your front shifter working correctly? If so, using the trim should eliminate the noise on both chainrings.