Fairwheel Bikes is known for their insanely lightweight customizations. We featured the world’s lightest road bike recently, something they had a big hand in creating, and now there’s this: A titanium Titus hardtail 29er that’s right at 16lbs.
But that’s only half the story.
Unlike the road bike, most of the weight savings on this bike comes from careful (albeit expensive) parts selection, not so much custom trickery. Where the real magic starts to happen on this frankenbike is with the shifting. Fairwheel took Shimano’s Di2 electronics and hacked them, both electronically and physically, to create a mountain bike that can either shift by automatically choosing the best front/rear combo or letting the rider shift manually…but either way, there’s only one shifter button.
See how they did it, and get a parts list, after the break…
First, the parts list, directly from Fairwheel’s website (some links are to the product pages on their site, where you can buy the goodies if you want):
- Frame: Titus
- Fork: Custom Cannondale Lefty
- Wheel Set:
- Rims: EDGE / ENVE Tubular 29er
- Rear Hub: Tune Cannonball
- Front Hub: Tune Dezible
- Spokes: Pillar 1422
- Rotors: Scrub Race Day Magnesium
- Skewers: KCNC Z6 Steel
- Tires: Dugast
- Handle Bar: EDGE / ENVE Sweep Bar
- Stem: EDGE / ENVE
- Headset: KCNC Morion M3 Ceramic
- Shifters: Custom
- Brakes: KCNC
- Rotors: Scrub Race Day
- Seatpost: KCNC Ti Pro Light
- Saddle: Tune Kom Vor
- Cranks: KCNC
- Chain: KMC
- Cassette: Custom Shimano
- Seat Collar: KCNC SC11
- Rear Derailleur: Tuned Shimano Di2
- Front Derailleur: Shimano Di2
- Grips: KCNC Eva
- Bar End Plugs: KCNC ‘Outta My Face
- Pedals: KCNC Knife Ti (Test Ride Purposes)
Fairwheel uses a lot of KCNC parts on their custom builds.
Look ma, no battery! One of the main things you may notice missing from the bike is the Di2 battery and the right shifter. Fairwheel tucked the battery into the seat tube (below). Keep reading to see what happened to the shifters…
SHIFTING MAGIC, AND A DOOR TO THE FUTURE
Fabricated by one of their site’s forum members, Jeff Roberson, the brains were hacked and customized to perform some gear ratio calculations on the fly. The brains are hidden inside an Enve (formerly Edge) Composites stem.
The wires drop out of the bottom to go the derailleurs and battery, and the control wire comes out near the stem cap.
Wires come out of a water bottle boss on the seat tube and run through a custom channel attached to the bottom of the driveside chainstay for the rear derailleur.
The shifting controls are set up with two operational options. In Automatic Mode, you simply hit the up or down button to shift up or down. The brain uses calculated gear inches to decide on the next proper gear combination and shifts front and rear accordingly. Fairwheel says it’s configured to avoid cross chaining and duplicate gear ratios as well as minimizing the amount of front chainring shifts it uses. Basically, it knows where the chain is and uses the best combo with the least amount of front shifting while maintaining a good chainline.
In Manual Mode, a single push of the up or down button shifts the rear derailleur up or down. Push both buttons at once and it shifts the front derailleur into whatever gear it’s not currently in – there’s no need to have an up and down button for the front because there are only two choices, and it knows which way it needs to shift. Of course, this means in its current form it’ll only work with a double chainring, but tweaks to the software mean it can essentially do anything.
Lastly, the system was built with a “gear dump” option. Hold either button down and it’ll dump up to 13 gears at once. They’ve timed it to move across the entire gear range in just over a second, but the speed at which it dumps (or adds) gears can be set however they want. (Yeah, we know, no one makes a 13-speed cog, but when you factor in how it uses the front derailleur too, there are more than 13 gear combos on this bike).
Yes, this is a beautiful system, but it only scratches the surface of what can be done. Add in power measurement and you could devise a bike that shifts on its own based on power output. Or speed and cadence. Or all three, which might be more appealing to roadies and triathletes than mountain bikers, but interesting nonetheless. As Jeff the programmer said, “If you can think of it, it can probably do it.”
Check Fairwheel’s website for the complete build story.