Image 1 of 17 The tuned Di2 rear derailleur moves the KMC chain across a SRAM XX cassette. (Image credit: Richard Hurst) Image 2 of 17 Fairwheel Bikes could have made its project bike even lighter by going with 26" wheels but opted for more capable 29" ones instead. (Image credit: Richard Hurst) Image 3 of 17 Say, where are all of the derailleur cables? (Image credit: Richard Hurst) Image 4 of 17 The rear derailleur gets the full KCNC treatment with red anodized aluminum pulleys and bolts. (Image credit: Richard Hurst) Image 5 of 17 Fairwheel Bikes uses Shimano's own satellite shifter for its Di2 mountain bike project. (Image credit: Richard Hurst) Image 6 of 17 The giant upper tube on the Cannondale Lefty fork makes the standard 1 1/8" head tube look tiny in comparison. (Image credit: Richard Hurst) Image 7 of 17 Claimed weight on the finished project is just 7.3kg (16.0lb). (Image credit: Richard Hurst) Image 8 of 17 The custom brain is tucked right inside the stem. (Image credit: Richard Hurst) Image 9 of 17 A Tune saddle is perched atop a KCNC aluminum post. (Image credit: Richard Hurst) Image 10 of 17 The single shifter wire is fed directly into the modified carbon stem. (Image credit: Richard Hurst) Image 11 of 17 The single shifter and internal wiring make for an unusually clean looking cockpit. (Image credit: Richard Hurst) Image 12 of 17 Fairwheel uses one of the seat tube bottle mounts as an access hole for the wiring kit. (Image credit: Richard Hurst) Image 13 of 17 The show bike is built with 47mm-wide Dugast tubulars but the stays have plenty of room for wider rubber. (Image credit: Richard Hurst) Image 14 of 17 The lightweight KCNC crank is fitted with 42/29T chainrings. (Image credit: Richard Hurst) Image 15 of 17 Fairwheel Bikes owner Jason Woznick says the custom Titus wasn't just built for show - he plans on using it as his everyday machine after Interbike. (Image credit: Richard Hurst) Image 16 of 17 Fairwheel Bikes' Titus hardtail 29er boasts a trick sequential shifting custom Shimano Dura-Ace Di2 transmission. (Image credit: Richard Hurst) Image 17 of 17 The sequential shifting, single shifter configuration should be a boon to endurance racers whose minds start to fade. (Image credit: Richard Hurst)

In the absence of Shimano's eventual release of an off-road version of its electronic transmission system, several companies and retailers have taken it upon themselves to create their own modifications – and most of the ones we've seen over the past few months have been very clever, if not downright brilliant.

Arizona-based retailer Fairwheel Bikes has crafted the best example we've seen yet. Sure, it's light and it's pretty with lots of anodized aluminum bits but the key feature is Fairwheel's custom designed electronic 'brain' that turns the 2x10 setup into a trick sequential shifting system using just one shifter.

In terms of user interface it's as simple as could be when set in 'race' mode: simply tap one button for an upshift and the other one for a downshift. According to Fairwheel's Jason Woznick, the custom brain calculates the gear inches and then shifts the front and/or rear derailleurs as needed to achieve the next logical ratio. Duplicate gears are ignored, too, and Woznick adds that the programming is designed to minimize cross-chaining and front derailleur shifts as well.

"As the bike sits, it's completely linear: two shift buttons, one for up and one for down," he said. "It can go from the 29/32T to the 42/11T hitting all thirteen equally spaced gears with only one front derailleur shift and without cross-chaining."

Alternatively, 'trail' mode allows for manual front and rear shifting as usual and full gear access across the entire range.

"When in manual mode, the two shifter buttons control just the rear derailleur, shifting it up and down as a normal Di2 system," Woznick told us. "To shift the front derailleur push both buttons at the same time. Since it's a double there's no need to tell it up or down, but just to shift. [Trail mode] isn't really that practical but it's still something we wanted as a possibility."

In fact, project software engineer Jeff Roberson says that, "really anything you can imagine is possible."

The system is connected to a PC via a standard USB cable and from there, Roberson can load as many modes as he wants and can also program any button combination to swap in between them.

Not surprisingly, the execution is well crafted, with most internal wiring, a custom battery pack that resides inside the frame, and the custom brain built right into the inside of an Enve Composites carbon stem. And luckily for Fairwheel, Shimano's latest satellite shifter is already appropriate for the application as well.

The rest of the bike impresses too, with a custom Titus titanium 29er hardtail frame, a Cannondale Lefty fork, Enve Composites tubular rims and fat Dugast tires, plus a wealth of lightweight goodies from Tune and KCNC. Claimed weight as pictured is just 7.3kg (16.0lb) and Woznick says it was built to be ridden, not just for show.

"After Interbike, I plan on switching to a set of Enve clinchers for daily riding and using this bike a lot," he said. "I think endurance events are a great place for something like this as you don't have to think about shifting when mental fatigue sets in. The other place we see this as a big step forward is for people that have the use of only one hand."

That being said, potential buyers who might want one of these for themselves had better be prepared to pay big bucks. According to Woznick, the cost for just the bike itself is estimated at between US$12,000-13,000 but the costs surrounding the custom brain is almost innumerable.

"I can't really answer the price on the brain as it doesn't have a real price," he said. "The fabrication part was the small cost – paying someone to engineer, design and write the software that controls it as well as how to wire it into the system would be the largest part of the brain expense. We don't really have any solid plans on making these available because it isn't just plug and play. There really is so much customization that goes into something like this. Everything from figuring out how to wire it together without using the stock plugs from Shimano to setting up chain lines and building custom batteries that fit inside the frame. It's not something that could easily be put into a package and sold."

Fairwheel will also have a number of other choice items on display at its Interbike booth (though we'll have to wait until then to shoot images firsthand), including a semi-wireless Di2 system, a 2.85kg (6.28lb) road bike, and a custom three-speed internally geared fixie with Ashima hydraulic brakes.

Vegas, here we come!

