Some mountain biker swear by thumbshifter gear levers, such as the Shimano Deore SL-MT62 lever shown below. Renowned for their reliability and functionality, these components can command surprisingly high prices when in good working and cosmetic condition.
One of the main advantages thumbshifters have over the more common, modern trigger shifters, is their ability to easily trim the front mech, in order to find its ideal position for each gear. The same can be said for throttle gear shifters, such as those produced by SRAM, Sachs and others.
Fast forward several decades, and we find that Shimano has finally realised that trimming a front mech can be useful, and that the 2015 XTR range will include this. According to Shimano:
The FD-M9050 uses computer controlled auto trim as the chain moves up and down the cassette to keep the drivetrain running smoothly.
In other words, Shimano have finally found a way to allow users of trigger shifters to trim their front mech, to avoid the annoying rubbing chain sound that can happen when the chain is at one of the extreme ends of the cassette. Albeit an extremely expensive and complicated way, that may take some time to trickle-down to more modest groupsets.
But I’ll be keeping my Deore thumbshifters for the time being.