Rear derailleur problem (shimano 105, road bike)

[SloAdventures]

Hello,
I few rides ago I started hearing weird noise in my rear derrailleur. When I switch to a larger gear it starts making loud noise. The chain moves but doesn't move soo smoothly and even sometimes for a second switches back into a lower gear and back. Is this a problem in the rear derailleur or somewhere else?
Thank you and greetings.

 

[Paulus]

It could be that the indexing has gone slightly out, or, the cable is a bit sticky and not moving freely.
Firstly give the mech, cassette and chain a good clean and lightly lube it up. Then lube the cable and clean at the points it goes through the ferrules into the outer cable.
See if the problem is still there.
Put the mech in the highest gear(smallest sprocket), detach the cable from the mech and see if the cable moves easily through the outer.
Check rear mech is vertical on the hanger and is not bent.
Or, and,
Try watching this---

View: https://youtu.be/UkZxPIZ1ngY?si=8zp1qHU0wWJ_XuCy

 

[Cycleops]

Try the above. If it started suddenly could be you've knocked it and it's bent the hanger or damaged the mech or both.
Eyeball it from the rear or let your LBS check it. If the hanger is bent you could bend it back but better a fix and the one the shop will recommend is replacement.

 

[ColinJ]

Try the above. If it started suddenly could be you've knocked it and it's bent the hanger or damaged the mech or both.
Eyeball it from the rear or let your LBS check it. If the hanger is bent you could bend it back but better a fix and the one the shop will recommend is replacement.

I dropped one of my bikes a couple of weeks ago and bent the rear mech. I didn't notice until the next time I rode it. The noise from it was so bad that I turned round after 5 minutes and went straight home. I managed to bend it back without too much difficulty and it is now working properly (and silently!) again.

 

[fossyant]

I'll bet on needing a new cable. The gear outer loop near the mech often get's crudded up after time, affecting changing. Ideally replace the inner and outer. Shimano SP41 Optislick made a huge difference to my 105 ten speed set up.

 

[Andy in Germany]

Try the above. If it started suddenly could be you've knocked it and it's bent the hanger or damaged the mech or both.
Eyeball it from the rear or let your LBS check it. If the hanger is bent you could bend it back but better a fix and the one the shop will recommend is replacement.

That is certainly best if the hanger is separate, but if it's part of the frame the LBS should have a tool to straighten it out.

 

[Andy in Germany]

Hello,
I few rides ago I started hearing weird noise in my rear derrailleur. When I switch to a larger gear it starts making loud noise. The chain moves but doesn't move soo smoothly and even sometimes for a second switches back into a lower gear and back. Is this a problem in the rear derailleur or somewhere else?
Thank you and greetings.

Have you had the cables changed recently or bought the bike new? Cables stretch with use, especially the one on the rear mech because it's longer and under a lot of tension all the time. IN that case re-tensioning will resolve the problem, and it's one of the easiest things to try

 

[Cycleops]

Yeahbut derailleurs don't just start making a lot of noise through being dirty.

 

[Andy in Germany]

Yeahbut derailleurs don't just start making a lot of noise through being dirty.

Depends on how dirty; I've come across a few rear mechs that have failed to work and made a noise due to the sheer volume of crud on the wheels. It has to be said, it's pretty obvious when it gets to that level.

 

[fossyant]

Yeahbut derailleurs don't just start making a lot of noise through being dirty.

They do if the cable is dirty and they aren't shifting and it suddenly get's to a point - i.e. more dirt get's dragged into the outer. My XT rear mech did this recently. Working perfectly one day, then the next, shifting wasn't great - checked cables and the rear loop was gritty. Replaced the outer and all was well.

My 105 10 speed slowly started getting less accurate on shifts. Changed the whole lot to SP41, crisp changes.

STI gears of 10 speed and above are quite pernickety if the cables aren't good.

And it's far easier and quicker to check the cable first !