Problem with front derailleur / gear shifter

[Roadhump]

Hoping someone can give some advice on the problem I am having with shifting between the 2 front rings on my Sirrus.

The shifter was stiff but operating, but then the chain stopped moving to the big ring. The problem was fixed but returned after a few days. I then took the bike to the LBS for a few jobs, including the shifter problem, and the mechanic said he had adjusted the limit screw, which had done the trick. However, before I even got home, it was not shifting again. Where there is normally a click when the gear is changed, there no longer was one and the cable and derailleur just fall back to the small ring. I took it back to the LBS and the mechanic inspected the shifter which he said was in good condition and working well, and fitted a new cable as the old one was worn, but again there is no click in the shifter and although the derailleur moves the chain over to the big ring, it falls back to the small ring as soon as pressure on the shifter is released. so the only front ring I can use is the small one/

It is a SRAM 2 trigger shifter fitted to a flat bar.

I can only think the shifter needs replacing or something is wrong at the derailleur end, and might just get them all replaced so the whole system is new, but if anyone has experience that may help, any advice that may provide clarity would be great.

 

[Heltor Chasca]

Cable replacement?

 

[Cycleops]

If there is no click in the shifter it could indicate the pawls are jammed up with gunk and won’t engage. Try removing the cover and blasting it with a spray cleaner. Worth a go.

View: https://youtu.be/8lJ3vCtWYvw

 

[Racing roadkill]

As above, it’s the sticky barrel on the trigger shifter issue. Follow the guide, you’ll be fine.

 

[Roadhump]

Cable replacement?

Already done that but hasn't improved things, I'll give the spray treatment a try, thanks guys.

 

[Levo-Lon]

Squirt some oil into the shifters ,and it should clear it.
Ive had it a few times when getting very muddy with the mtb.
Plus i used to wash it upside down to clear mud, so my shifters got covered in dirty water.

I wash on a stand now which is far better

 

[Roadhump]

I did the WD40 thing and it started to click again, still wouldn't shift the chain the full way, but was obviously moving it, so I had a fiddle with the limit screw and the barrel adjuster at the shifter end of the cable and it started to do the job properly. Then I took the bike out for a 30 mile ride and changed between the 2 front rings quite a lot, it was working well, apart from once when the derailleur shifted, but seemingly not far enough because the chain wouldn't go onto the big ring - I rode along on the small ring for about a minute, fiddled with the barrel adjuster a little bit and tried again, and it worked okay again.

I am going to give it another blast of WD40 in a few days time, then spray some lube in and see how it goes.

Thanks again for the very useful advice.

 

[Illaveago]

As mentioned above the ratchet mechanism in the handlebar shifter gums up and doesn't engage properly, preventing the cable from pulling the mechanism the full amount. A good clean and light oil or grease should cure things. As the limit screws have been adjusted they may need re setting once you get things operating again.