In a move that's taken the cycling world by complete surprise, Shimano, the usually conservative drivetrain and fishing giant, has released a novel chain guide system that allows riders to use more than one chainring. Not only does the small, moving mechanical guide keep you from dropping a chain, it also moves it from one chainring to another. This gives riders a massive gearing range to choose from.
The novel guide, which can be had in bolt-on and clamp-on versions to fit a variety of different bikes, is controlled in much the same way your rear derailleur is operated: with a cable that's pulled or released by way of a shifter, only this one is found on the left side of the handlebar rather than the right. While your rear shifter has up to twelve indexing clicks, Shimano's moveable chain guide system has either two or three that correspond with a special crankset that lets riders mount two or even three chainrings. Yup, you read that right - THREE differently sized chainrings.
Being able to run up to three chainrings means that we could have a 36-speed drivetrain when combined with their rumoured 12-speed system
. Want to pedal your bike up a climb at a pace that would make crawling seem like a dangerous, high-speed endeavor? If so, you'll be able to pair a 50-tooth cog with a 22-tooth chainring to get a wall-scaling 0.44 low ratio, or a 10-tooth cog and wild 42-tooth 'ring for a 4.20 ratio, which is by far the highest ratio. Sure, there they'll be a few repeats in there, but THIRTY-SIX-SPEEDS, SO WHO CARES.
The 10-50 spread cassette on its own provides a 500-percent range, but when you factor in the 22-tooth and 42-tooth 'ring (that's as large as some cogs!) you end up with a mind-boggling 950-percent range. SRAM'S Eagle system has a paltry 500-percent that surely leaves many riders asking for easier low gears, and even a 12-speed Pinion C.Line gearbox sports a barely manageable 600-percent range.
I haven't tried Shimano's moveable chain guide and multi-chainring drivetrain yet, but I'm blown away that we've been getting by without a 22/50 combo and 950-percent range. That's about to change and riding our bikes will get even less challenging, thank God. The days of having to sweat and expend energy to get to the top of the mountain will soon be behind us, brothers and sisters, which, when you take into account IMBA's new robotic Flowmaster trail sanitizing machine
, will ensure that absolutely anyone and everyone can enjoy mountain biking without having to work hard. The future is here!
Shimano has been mum on compatibility, but it's highly likely that frame manufacturers will have to adapt their upcoming designs to provide the necessary clearance for three chainrings. In order for this to happen, I expect to see skinnier bottom bracket shells, less tire clearance, and longer chainstay lengths, all changes that will make your current bike obsolete and leave you having to trade it for PlayStation games on the Pinkbike buy and sell. I bet they'll soon be a time when we question how we ever got by with fixed chain guides.
Word is that the concept has been in development since the mid-1900s, so while Shimano hasn't released pricing or availability yet, you can expect the system to be highly developed and completely trouble-free when they do decide to make it available to the public sometime in 2018. I bet it'll be easy to set up, too. I suspect that SRAM will respond with a movable chain guide of their own, so keep an eye out for that as well.