So Ive been out at Hamsterley this morning, about halfway round I noticed the rear shifting from smaller to larger sprockets become very difficult all of a sudden – going the other way from larger to smaller sprockets is still fine. My bike is only 2 rides old (a Cube Stereo 29er) so I wouldn’t expect any issues yet, nor would I expect to have to change cables yet as they are fully sealed, at least on the bits that aren’t internally routed. What are the most likely causes – knackered shifter? Knackered cable? The mech/hanger are nice and straight. There does seem to be a lot of ‘play’ in the thumb shifter before any cable movement, about a cm or so. Opinions please folks.

Sram?

XT 2×10, the one with the clutch on the rear mech.

It won’t be the derailleur.

Pull the inner cable all the way out and inspect it – check it hasn’t frayed where it sits inside the outer.

Leave it connected to the shifter, and hold one end, activate the shifter up and down, as if changing gear, and see if there is any resistance then.

Hopefully it’s just sudden corrosion on the inner cable causing excess friction.

Ive had a sram shifter fail that caused the problem you describe. Check the cable as described above and operate shifter to see if is ok. Could the clutch on the mech cause a problem? Shift with wheel removed to eliminate it.

The cable outer at the derailleur needs changing every six months, more in wet muddy conditions.

Try shifting without the mech clutch on, should be nice and light. If it’s stiff when the clutch is back on it may need adjustment to your liking

Cheers folks, ive changed the cable and lower half of the outers and all seems better…just a bit crap that its lasted only 3 rides.