maoglone

Okay. I have Shimano Deore shifters on my commuter. There are 3 rings in the front, 8 in the rear. The front shifter/derailleur works just fine, but the rear shifter/derailleur, over the past couple days, has been acting up on me. When I shift up, it's slow to shift, and once I shift to 4th gear (I'm keeping the chain in the middle on the front), It's a struggle to get the derailleur to respond to the shifter. Eventually, and with much work, I can get the rear derailleur to 7th, but I can't get the bike to shift onto the smallest (8th) ring, no matter what I do.

The shifter used to click with each shift upward, but now it doesn't.

Shifting downward is a problem, too, in much the same way.

Anyone come across this before? Does my derailleur just need to be adjusted, or is the shifter broken?

operator

https://www.parktool.com/repair/readhowto.asp?id=64

Also check cables/housing. At first glance it sounds like your cable tension is out of whack. Check also for chain wear and lubeness.

maoglone

All right. Took the top cover off of the shifter, and it looks like the cable's about to go. So, I'm off to buy a new shifter cable and then learn how to put it in. Thanks for the help.