105 Rear derailer shifting

[GNU]

Hi Guys,

Short story, I'm pretty new to road cycling and ran into some grief with 2 punctures at the same time on the weekend. I only carried 1 spare (buying a puncture kit for the saddle bag this week). Walked to a nearby bike shop which were super nice and helpful with upgrading my thin stock tyres to thinker training tyres to prevent future problems. However, on my ride home my chain came off twice whilst reverse pedalling and my gear shifts were horriblely noise and kept slipping. I've never had this problem with my bike before (Malvern Star oppy A5, full shimano 105 groupset).

I'm guessing the mechanic knocked something by accident. Its to far from home to take it back. Is this something I should tinker with myself, or should I take it to a shop for tuning? Any advice or links welcomed.

[Mrfenejeans]

http://bicycleswest.com/how-to/how-to-adjust-your-rear-derailleur-pg120.htm

This should help point you in the right direction.

[Stuey]

Sounds like the rear derailleur (RD) or the RD hanger might be bent, if the mechanic accidentally rested it on the ground while doing the tyre change. Other possibility is that the RD cable outer has come out of its seat on the RD adjuster, or on the frame stop. It could have caught on something while the mechanic was working on it, and would throw the adjustment out.

First thing is to check is whether the RD cage is vertical, and should be in line with the big cog on the rear when the bike is in its lowest gear.

Stu

[GNU]

Thanks for the replies. I adjusted the cable by screwing it counter clockwise and that seems to have fixed the problem. Quiet new to tinkering and didn't want to screw it up anymore

[twizzle]

However, on my ride home my chain came off twice whilst reverse pedalling and my gear shifts were horriblely noise and kept slipping. I've never had this problem with my bike before (Malvern Star oppy A5, full shimano 105 groupset).

Of course, the obvious explanation for the bad gear shifting is simply that the wheel isn't mounted properly in the dropouts.

Secondly, I have highlighted your primary mistake. Don't do that.

[clackers]

Thanks for the replies. I adjusted the cable by screwing it counter clockwise and that seems to have fixed the problem. Quiet new to tinkering and didn't want to screw it up anymore

Unless something traumatic has happened, GNU, you'll often find that it's this cable tension that's changed, perhaps by stretching, and you hear that ticking or rattle from the chain.

The barrel adjuster will inch the derailleur back into place, and you can do that bit yourself.

[Stuey]

I guess make more dramatic suggestions for what the problem is because I can't believe such basics can be missed by a paid mechanic, like not seating the wheel.

GNU, if the shifting was OK before the puncture, then you shouldn't have needed to adjust the RD (at least, not enough to stop the chain coming off) so I'd check what Twizzle suggested etc. as something must've moved.

[twizzle]

I can play that game.

The earths magentic field is finally swapping, and it's pulling the derailleur the wrong way. You should wrap the whole bike in aluminium foil.

[Stuey]

The earths magentic field is finally swapping...

NOW you're making things up...

[twizzle]

The earths magentic field is finally swapping...

NOW you're making things up...

Lol - I have to use Internet exploder, and it doesn't have a spell checker built in. I miss firefox.