Ive used XT for 10yrs and the shifters have always been super smooth. I have some brand new thumb shifters M770 and they are the worst made hunk of junk ive ever put on my bike. The shifting is way too deliberate, you must pull pretty hard to get the chain down on front and rear. Pull hard then a audible hard clunk, if it shifts at all. Even with the shifters held in your hand with no housings and the other hand putting tension on the cable it still is difficult.
Giving them away and thought id never hear myself say this but switching over to SRAM.
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