Many people are not aware of what quality the different gears of their bikes have. Shimano, Campagnolo (in the past), and SRAM makes gears in all types of quality and price, and the MTB-gears are listed under here, from cheapest to best:
Shimano
Acera (Cheapest)
Alivio
Deore
ZEE
SLX
Deore XT
Saint
XT
XTR (Best)
SRAM
X5 (Cheapest)
X7
X9
X0
X01
XX
XX1 (Best)
Campagnolo
Campagnolo used to make MTB-geargroups in the 90's. They were:
Themis (Cheapest)
Icarus
Centaur
Olympus
Euclid
Record OR
You can see the list with the roadbike geargroups here
Written by René