Photokina 2014 highlights

Shimano announces XTR Di2 electronic shifting for mountain bikes

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May 30, 2014

The system's SC-M9050 Display Unit

The system's SC-M9050 Display Unit

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In 2009 Shimano brought electronic gear-shifting to road bikes, in the form of its Dura-Ace Di2 group. The slightly-less-pricey Ultegra Di2 system followed, although it was still aimed at roadies. Today, however, the company announced the upcoming release of XTR M9050 Di2, which will allow mountain bikers to swap their derailleur cables for electrical wiring.

As with the road versions of the system, XTR Di2 electronically relays signals from the shifters to motors in the front and rear derailleurs. This means that shifts are consistently quick and smooth, as they aren't affected by the slackening of stretched steel cables or by contaminants within the cable housings. That said, users will have to keep an eye on the battery level, and they'll definitely want to avoid damaging the wires ... sorry, the system isn't wireless.

Because the thumb levers on the new Firebolt shifters don't have to be aligned with a mechanical mechanism, they're free to be rotated around the shifter body in order to best suit the rider. Their default position is also said to be more ergonomic than that of regular shift levers, plus they require less effort to push.

Additionally, using the Shimano Synchronized Shift function, the system can shift both the front and rear derailleurs at once via a single shifter. Along the same lines as IXOW's lower-tech Synchrobox, the system coordinates the two derailleurs with one another, so that they shift together to attain the desired gear ratios without "cross-chaining."

The XTR Di2 Firebolt shifter
The XTR Di2 Firebolt shifter

Besides making shifting quicker and simpler, the feature also allows riders to equip their bike with just one shifter if they so desire. If they'd prefer to manage both derailleurs themselves, however, they can do so by simply switching to Manual on the bar-mounted SC-M9050 Display Unit. That unit also indicates battery level and the gear currently selected, plus it sounds a notification tone when automatic front derailleur shifts are about to occur. It additionally houses the system's battery-charging port.

Other features of XTR Di2 include automated trim on the front derailleur (to keep the chain from rubbing on it), a low-profile clutch-style rear derailleur, and compatibility with 1x, 2x and 3x drivetrains. The system is designed to work with Shimano's existing XTR M9000 group of components. According to a report on BikeRumor, the weight of a 2x single-shifter Di2 setup should be about the same as an equivalent M9000 mechanical system.

Pricing has yet to be announced, and availability is scheduled for the fourth quarter of this year.

Source: Shimano via BikeRumor

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
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3 Comments

I love new toys, but I think I'll pass on this one. Then again it could be fun to test it to compare with the traditional ways and also see how it does once it's covered with mud (knowing Shimano I bet they have that covered).

I wonder if the system lets you toggle between normal and "rapid rise" mode, that would a neat bonus feature.

BZD
1st June, 2014 @ 08:35 am PDT

This system is electro-mechanical, not exclusively 'electronic' - I would like to see electrons move a derailleur directly.

And why apologise that the link between controller and the servo motors is not wireless? Why would you want a wireless link for a distance of a metre or so?

Sheldon Cooper
2nd June, 2014 @ 02:12 am PDT

I assume that this is only one step away from being an automated system, with change down to low ratio when coming to a halt, being one of the many benefits (something that I all too often forget about until the lights change and I am left looking the amateur that I really am).

Mel Tisdale
2nd June, 2014 @ 04:04 am PDT
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