No more gunked-up cables, ever. Perfect shifts, every single time, front and rear, regardless of what sort of devious jamming exploits mud, sticks, grass or course tape may attempt. Front shifting under extreme load without concern. Nearly impossible, but it certainly sounds nice, eh?
Well, we’re getting closer, thanks to a bit of creativity from the folks at K-Edge. The company, known for its chain catchers and ring guards, is modifying Shimano Dura-Ace Di2 road groups for use on a mountain bike. (http://singletrack.competitor.com/?p=13815) They mount a long cage on the rear derailleur (and have a short cage version in the works) and have created a custom mount for Shimano’s Di2 satellite shifters, originally designed to be placed on the tops of a road bar. The system can easily handle a 36t rear cog, and the shifters mount up to a brake lever similar to SRAM’s MatchMaker for an impressively clean cockpit.
I rode Ki2 on an Orbea Alma 29er with an XTR 11-36 tooth cassette and 26/40 tooth double crankset over the course of five weeks, including two cross country races.
A full season in a harsher climate (we don’t really ride in mud here because the mud is actually concrete and walking home sucks) might prove differently, but I had zero durability issues with the Ki2 setup. Given Di2’s success in ‘cross, I imagine it can handle mud pretty well though.
Impacts could be a different story though, given that both derailleur bodies are designed with road use in mind. However, the Dura-Ace rear derailleur seems up to the task of taking on trails, even after taking a few solid rock hits. Its “crash recovery” system was engaged once after I clipped the derailleur body (and my own body) on a tree, hard enough to bend the hanger a bit. The derailleur re-aligned itself after a few shifts and I was on my way. Impressive and appreciated.
With intelligently routed wiring, water isn’t an issue. All the connectors are waterproof, so the only issue comes with nicking a cable. Keep everything hidden away and that is a moot issue.
The shifter pods are durable CNC aluminum, though the buttons themselves are plastic. In theory, a hard crash could damage them.
Though the latest SRAM XX group has a small leg up on XTR when it comes to front shifting, Di2 has the best front shifting available on the road, bar none. That talent, transferred to the dirt, becomes even more impressive and important, and puts Shimano back in the lead in the front-shift war.
With the Di2 front derailleur and XTR chainrings, front-shifting under load is precise, predictable and reliable. Instant big-ring access at the top of a climb, without having to let off the gas even a little, is much appreciated. No grinding and noises; the chain is instantly picked up and you’re on your way.
As on the road, I feel the rear shifting is lacking just a hair compared to mechanical systems, largely because there is no way to dump multiple gears at once. This feature is even more important on a mountain bike, where screaming down a hill only to run into a gnarly climb is common. I rarely have to go straight from my 53×11 to 39×25 on the road, but I go from 40×11 to 26×36 (or close to it) pretty regularly on the dirt. Having to push a button 10 times, rather than 3 or 4, is a pain. Perhaps I just never played enough video games as a child, and my thumb speed is below average.
If Shimano plans to come out with an electronic XTR group (and I hope they do), they need to add in the ability to dump multiple gears. Making the “button” a paddle, with multiple stops, would seem to be the best way to do this.
There is something to be said for consistency, though, particularly when brain and body are under pressure. I often mis-shift when on the limit, either pushing a lever too far or not far enough. That’s impossible with Ki2; the shifts are perfect every time. You know exactly what is going to happen when you push that button.
Ergonomics of the shifters is great. The pods are placed within easy thumb’s reach, and because one button is slightly larger than the other, it’s easy to feel which one you’re pushing.
Here’s the whopper, and the reason why I held off on writing this review until after I had ridden the new Ultegra Di2 group.
A regular Di2 “upgrade kit” from Shimano goes for about $2,900. That’s for the derailleurs, shifters, battery, and wiring harness. Ki2 will set you back $3,385, about $500 more, for modified versions of the same stuff. Ouch.
Thankfully, K-Edge is already working on an Ultegra Di2 version, which should knock at least $1,000 off the price, probably more. And as I wrote recently, the new Ui2 is actually better in many ways than its big brother. I’d wait for that. (http://www.velonews.com/?p=187814)
Would I take a Ki2 group over SRAM XX or XTR? I loved the front shifting. The rear shifting is adequate. The rear derailleur doesn’t need a long cage when run with a double crankset, so once the short cage version appears the setup will appeal to me more. Push-button shifting is great when on the limit. The clean look is very appealing—it looks like you’re on a singlespeed. But the lack of gear dumping is a bummer.
So the answer is: maybe. When they start selling modified Ultegra Di2, then I’ll lean toward, “yes.”