Just been building a bike for my son and the shifting isn't very nice! I have fitted new outers and inners and the rings etc were off his old bike.
He has Deore shifters and XT mechs front and rear. The rear is a long cage M771. Could it be the shifters causing this? I have XTR on my bike with the shifters and as you would expect, the shifting is flawless.
He's not the biggest of 11 yr olds and anything to make shifting easier, is what I am looking for.

I've got Deore's on several of our bikes and they shift just fine. Perhaps not quite as slick as the XT and XTR we have on other bikes but not so you'd notice a problem.

In my experience the quality of the shifters makes the biggest difference.

I upgraded to an XTR rear mech with Deore shifters and was a bit disappointed. However, when I changed to XTR shifters the improvement was huge.

There is a big difference in shifting between LX and Deore. I had Deore shifters some time ago and my mate had LX on his bike. LX were very close to the XT performance wise. Short moves of the levers to change gear and much more precise than Deore. However a Deore drivetrain should still be shifting ok and the difference would be bigger in poor condition, mud etc. Maybe check the cables if the cable did not split somewhere or something like that.

All new cables, so not that. They shift ok but need far more of a push than my XTR. Not as responsive, if you know what I mean?

Yep, that is how I remember Deore shifters 🙂 give Lx a try, even the blue/black ones work as quick as xt and are pretty cheap now.

LX or SLX over Deore is a massive difference.

Just changed from Deore to XT and miles better

XTR will be quicker than Deore as XTR change on the push where as Deore change when you release the lever.