First Impressions: Shimano XTR Di2

Is it as electrifying as promised?

Few subjects could be as polarizing as the advent of electronic shifting in mountain biking. People seem to love it or hate it, even before they’ve had the chance to try it out on the trail. We got to ride a bike outfitted with the much-anticipated Shimano XTR Di2 system during Interbike’s 2014 Outdoor Demo, and we found it downright impressive. Our video gives an overview of XTR Di2, along with some impressions after our first ride on it.

Electronic shifting has been part of the road scene for about five years now, and it is widely viewed as efficient and reliable—if not outright superior to traditional mechanical systems. But bring up the topic of an electronic drivetrain on a mountain bike and you’re guaranteed to have a lively debate. Many of us mountain bikers seem to be instinctively resistant to dramatic changes in technology, even though it’s clear that we’ve all benefited immensely from the giant technological leaps our sport has made over the past couple of decades.

Only several years ago, many of us were thumbing our noses at dropper posts, claiming that we rode just fine with traditional seatposts. But fast forward to today, and most mountain bikers feel naked if they hop on a bike without a dropper post.

After spending an hour or so riding the trails of Bootleg Canyon on a bike decked out with the new Shimano XTR Di2 system, it’s hard not to wonder how we’ll be viewing mechanical drivetrains several years down the road.

Even after the first few shifts, it’s impossible not to notice how crisp and precise Di2 is—especially when shifting under load. Once I became comfortable with the system, I began testing how it would perform under heavy pressure, such as shifting in mid-pedal stroke while standing out of the saddle on a steep climb. Wincing in anticipation of that horrible grinding sound that usually accompanies such sloppy riding, I was surprised by how instant, crisp and noise-free the experience was.

The Di2 rear derailleur is actually pretty stealthy considering that there's a powerful servo motor hidden inside. The weight of motor sits on the other side of the fixing bolt, acting as a counterweight for the derailleur. Shimano says it actually gets bounced around less than the mechanical one because of this. Also, the clutch force is now externally adjustable, a definite bonus.
The Di2 rear derailleur is actually pretty stealthy considering that there’s a powerful servo motor hidden inside.

The customization options of Di2 are equally mind-blowing, with the possibility of programming a single shifter to operate both derailleurs. Shimano calls this ‘Synchronized Shift,’ and it allows you to control both derailleurs via two triggers on either the left or right side of your cockpit, depending on your preference. On climbs, once you’ve run out of cogs on the back the system will make an audible tone to warn you that the next time you hit the trigger the front derailleur will shift. A split second after the chain drops into the smaller ring, the rear derailleur will make one ‘make-up shift,’ moving from the largest to second-largest cog. Shimano’s philosophy is that a single shift should never be more than a 15 percent change in cadence, so when you drop into the granny, the rear derailleur automatically accommodates.

I also appreciated the system’s ergonomics, which allow for a highly adjustable cockpit that makes it easy to control shifting and braking without moving your hands from a position of control. The triggers offer several adjustment positions that allow you to dial in your cockpit so precisely you’ll never need to slide your hand along your grips to reach your triggers.

The battery mounts to a bottle cage mount, similar to a mini pump.
The battery mounts to a bottle cage mount, similar to a mini pump. There’s also an internal battery available for bikes designed for Di2.

It’s hard to troubleshoot a new system after barely spending an hour on the trail with it, but Di2 certainly shows the promise of a much simpler and less error-prone ride in the future. And we’ve barely even scratched the surface of the custom-tuning possibilities afforded by the Synchronized Shift modes.

Of course all this comes at a price: Shimano says that XTR Di2 with a 1x drivetrain will cost about $3,500, and a 2x system will be an additional few hundred dollars. But Shimano officials stress that the point of introducing this advancement is not to phase out already reliable mechanical systems, but rather to achieve the most efficient, high-performance system they can produce for their world-class athletes.

More news about the Shimano XTR Di2:

News: Shimano Announces XTR Di2