There's been little doubt that Shimano engineers have been developing an electronic version of the company's top-end XTR mountain bike group but it's only recently that prototypes have been spotted in public. Canadian cross-country racer Geoff Kabush (Scott-3Rox Racing Team) appears to be testing a Di2 drivetrain on his new Scott Scale 29, an observation based on two images he posted on Twitter this afternoon.
Accompanying the images, he wrote: “Something feels different today” and “That’s weird. Someone just put a battery on my bike”. Shimano officials declined to comment but we managed to reach team mechanic Gary Wolff. He confirmed that Kabush was indeed testing prototype equipment, but offered no additional information.
That means we have little technical information to share at the moment, aside from to say that the system apparently exists and is undergoing testing. Kabush did post a close-up image of the battery, which looks to use an identical pack (and mount) to Shimano's road-going Dura-Ace Di2 and Ultegra Di2 groups.
It's safe to assume, however, that much of the system will be analogous to Dura-Ace Di2, including the powerful servo-actuated front derailleur and motor-enhanced rear derailleur – both of which we expect to be modestly upsized relative to the current mechanical analogues. Currently we don't have any images of the shift buttons but based on what Shimano have done with road-going Di2, we expect button placement to be similar to that of standard Rapidfire shifters, not the modified top-mounted satellite shifters used on third-party creations.
Pundits will undoubtedly question the wisdom of an electronic drivetrain for mountain bike use but we'd argue that it makes even more sense than on the road when viewed in the microcosm of World Cup-level racing where costs are largely inconsequential. The weatherproof nature of the system should maintain perfect adjustment regardless of conditions, the advantages of being able to shift under load up front are even more applicable here, and the often convoluted routing of modern-day full-suspension bikes becomes a complete non-issue.
Then again, it's possible that Kabush posted the images merely as a prank. His comments provide little clue either way. "I can't talk about my new battery powered heated grip yet," he told BikeRadar, "but I'd inquire at Fox if you want – or try for some spy photos in Texas." Kabush also posted the following to his Twitter feed later on: "Assumptions, assumptions, assumptions......."
Is Canadian cross-country racer Geoff Kabush (Scott-3Rox) testing a new Shimano XTR Di2 prototype transmission? Perhaps – but then again, maybe not