jb_alphamale

I have a bike with a rear derailleur Shimano Altus for 8 cogs. Everything on this bike is stock and it worked fine for the last 3 years. About two weeks ago I noticed that when I up-shift from 4 to 5 cog it is not shifting and it does that noise when it tries to.If I shift again then it jumps from 4 to 6 fine.Backwards shifts fine from 6 to 5 and from 5 to 4. It does the same for all 3 chain rings. I played with the derailleur (cable, adjuster, L and H screws). No matter what I do there is no way I can make it work properly. Sometimes it shifts properly and I noticed it does it at higher speeds.
I can live with it but I'm wondering if anybody has any solution or seen this.

joejack951

Well, you made a mistake by playing with the low and high stop screws before reading up on the subject. If the derailler used to shift fine, the problem does not lie in the adjustment of the stop screws. The problem is almost definitely a cable tension issue. As the components break-in, more slop is introduced into the system and cable tension decreases. Simply adding a little more tension solves the problem. You can read up at www.parktool.com and you'll need to because the high and low stop screws need to be properly reset. This means disconnecting the shift cable and basically starting from scratch (unless you were careful enough and returned them back to their starting points after realizing they weren't the problem).

The above assumes that you haven't recently dropped the bike and that your chain and cassette are in decent order.

jb_alphamale

When I get home I'll readjust the derailleur from scratch as instructed. Indeed I've moved the screws from their initial position and I did put them back as they were but I'm not sure anymore. I'll follow the instructions and report back. Thank you.

jb_alphamale

I readjusted the derailleur from scratch with video instructions found on the net. Everything works fine now. Thanks for your help.