Bicycle Mechanics - Shimano 105 missing downshifts.

I have 9 spd 105, and occassionally, when I go to down shift, usually onto the biggest cogs, the lever moves with absolutely no resistance, and of course, no shift. I let it return and shift again and it works. I cleaned it out with solvent and haven't been able to check it yet, but if its not fixed, any ideas?

I would flush out the shifters really well with WD40. New shift cables and housings may also be needed. You could try lubricating the cable where it runs through the short housing just before the rear derailleur. Often this will improve shifting.

Al

Sometimes they get gooked up and will miss shifts like that. I have used carb cleaner (spray can variety) w/ a lot of success. Spray in, let sit a few mins, wipe off excess and shift away good as new. Spray triflow will also sometimes work.

Sometimes they get gooked up and will miss shifts like that. I have used carb cleaner (spray can variety) w/ a lot of success. Spray in, let sit a few mins, wipe off excess and shift away good as new. Spray triflow will also sometimes work.
Good tip. I used wd40, but if that doesn't work, then a more powerful solvent makes sense.

Check where the cable runs under the bottom bracket, this spot is a catch-all for crap.

I would flush out the shifters really well with WD40. New shift cables and housings may also be needed. You could try lubricating the cable where it runs through the short housing just before the rear derailleur. Often this will improve shifting.

Al
I follow up the WD40 with a healthy spray of Finish Line Teflon Plus chainlube. That 1-2 combo has worked three out of three times for me. Save me and my freinds a lot of $$$ not having to replace brifters.