Road Cycling - Shimano 105 STI Shifters not Shifting all the time

Hi guys,

On my Fens, the shifters aren't shifting all the time. I'll be pedaling and press the shifter and nothing happens. I'll press it again nothing. Again - finally it shifts, sometimes it doesn't. What's going on?

Thanks a lot,

-Mike

Um, is this your front der?
Maybe you're trimming it?

Front or rear? Any particular shifts give more problems than other? Cables tight?

Actually it's the rear derailer. Sorry, I'm rather new at this and forgot that information. What do you mean by trimming it? Cables seems tight and it seems pretty random.

A few questions.

Are you talking about the front or rear?
Will it shift in one direction, but not the other (e.g., going from a larger to a smaller cog, but not smaller to larger)?

How old / how much use on these shifters?

It could be a range of things. E.g., I have an older Shimano 600 set up on my bike trailer pulling bike and was getting no shifting from big to small on my front derailleur. Based on some advice from my LBS, I removed the shifter, blew it out with some high pressure air, replaced the cables, and it now works perfectly. Your problem may vary, but a little more info is needed.

Thanks for the reply. It happens when both going from small to large and visa versa. The shifters are brand new off on a Windsor Fens 07 model from bikesdirect.

Can any derailer adjustments be made that may fix this, it seems like some are needed. Or is this a seperate issue?

Thanks,

-Mike

Theres a tiny little screw that threads through the upshift lever to the downshift lever. If thats missing (and it rattles free very easily), that could be your problem.