Rear shifting issues

robthehungrymonkey

In the last couple of days i've had a problem with my rear shifting.

It quite often (i think maybe all the time) won't shift onto bigger rings on the rear cassette, after shifting down. E.g. shifting up and up and up, and then trying go down when approaching a junction (quite annoying). It does seem to work if i try to go down (it fails) and then by clicking to go up a gear it kind of jogs it back into being able to downshift.

I'm pretty useless at working these sort of things out :oops:

Any idea where to start?

(Shimano 105 by the way - a few years old)

maddog 2

if it doesn't want shift up onto a bigger sprocket, and that happens on all sprockets then you need a bit more cable tension (they go a bit slack over time). Just turn the adjuster on the back of the mech a turn or so anticlockwise.

if it doesn't want shift down onto a smaller sprocket, and that happens on all sprockets then you need a bit less tension (unusual), or...

if it doesn't like shifting down but is fine shifting up then your cable could be starting to corrode/deteriorate and the spring in the mech can't quite overcome the drag in the cable. Replace cable and relube.

robthehungrymonkey

Many thanks maddog!

That's exactly what i needed to know. The cables were replaced by my LBS recently, so i'm sure a a little tighten up will do wonders.

robthehungrymonkey

Sorry, being dumb again...

is it the screw circled?



:oops:

John.T

No. That is the B tension screw. The one you want is the one with the outer cable going through it near the bottom of the pic. You should also find one on the down tube where the outer cable fron the shifter is fixed. Either of these can be used. Normaly you would set the indexing at the rear and use the front one for any fine tuning needed on the road.

robthehungrymonkey

ahhhhhhhhhhhh

:oops:

THanks again.