Gear levers are cable operated levers which move the front or rear mech which in turn moves the chain to a different cog, ie change gear. Each movement of the lever pulls the cable a set distance moving the mech a corresponding set distance to another cog. This indexing of the gears means no more searching for gears as every time you hear a click the gear is changed.
Each off-road groupset manufacturer has a slightly different method of shifting but all are mounted on the handlebars beside the brake levers. Another constant is rear gears are always changed using the right hand gear lever and front gears are always changed using the left hand gear lever no matter the make or system so at least that bit is easy to remember.
The three types of mountain bike gear lever are trigger, twist and thumb shifter
Trigger – each gear lever has two paddles, one on the front operated by the forefinger and the other on the rear operated by the thumb. The right hand gear lever always controls the rear mech where the forefinger paddle releases the cable moving the mech down the cassette to a harder gear and alternatively the thumb paddle pulls the cable tight moving the mech up the cassette to an easier gear. The left hand gear lever works in reverse to the right so the forefinger makes it easier while the thumb paddle makes it harder. Shimano call their version of this system Rapidfire and SRAM X-ACTUATION and Exact Actuation.
Twist – here the gear lever is a grip around the handlebar which you twist to pull and release the cable to change gears. Twist the right hand lever towards you to make the gear easier and away for harder and again the left hand is the reverse with towards you making it harder and away easier.
Thumb – these are the simplest form of gear levers which sit above the bars and one lever pivots to pull or release the cable. Push the lever away from you on the right hand to make it easier and towards you to make it harder. Again, the left works opposite so pushing the lever away makes it harder while pulling it towards you easier.
Unfortunately, Shimano and SRAM rear gear levers are not compatible with the other manufacturer’s rear mech as the amount of cable pull differs slightly between both. Some front mechs can be compatible across manufacturers and this will be pointed out in the specifications. Each manufacturer also recommends using similar groupset components from each gear system as some mechs may not work with differing numbers of gears, ie Shimano XTR 10 speed levers must use a 10 speed rear mech and so on.
The hierarchy of Shimano mountain bike gear levers from professional downwards is as follows:
Downhill / Freeride
The hierarchy of SRAM mountain bike gear levers from professional to entry level is as follows: