Rear derailleur only shifting to larger cogs

[Mike_P]

Bit bemused, apart from the smaller cogs I cannot get the hybrids rear derailleur, a Shimano Tourney 6/7 speed, to drop onto a smaller cog, changes up to each larger cog without a problem. Is it new derailleur time?

 

[Shearwater Missile]

With the cable removed it should drop into the the smallest cog. If it can do it then, then I`d say that either cable problem or the hanger has taken a knock.

 

[Globalti]

Absolutely not new derailleur time, they seldom malfunction. When was the last time you changed the cable outer where it curves round to the adjuster? More than six months and it's probably crudded up and rusty and preventing the RD from pulling over where the spring is weakest. As above remove the cable to see what happens.

 

[Mike_P]

Thanks, had replaced that outer but had not noticed one of the ferrules was slightly bent.

 

[sleuthey]

when you do shift in the larger cogs does the number on the shifter match the cog on the cassette?

 

[Cycleops]

Yes, remove the cable from the derailleur clamp and move the mech across by hand, it should stop in line with the large and small cogs at the extremes. If it doesn’t the hi-lo screws need adjusting. Connect up the cable once complete and adjust the cable tension.

 

[Mike_P]

Replacing the ferrule and well lubing the inside of the outer did the trick. Was still a bit sticky on the largest cog but then that easied presumably as the oil spread inside the outer. The bike was really having an off day, the rear tyre needed pumping up and when I removed the pump the end of the presta valve broke off; the inner tube is a Joe's No Flat so it's no doubt a well sealed the valve and it going to be very messy when the time comes to take the inner tube off it

 

[Cycleops]

Always a good idea when replacing cables to oil or grease them, my bike shop guy down here reckons the outers start going rusty with three months if not done.