Geometry and Frame Design
|BMC's Trailfox TF01: Ready to Race|
BMC's new Trailfox TF01 is the Swiss company's flagship enduro race bike, intended to excel on the rough courses found on the Enduro World Series circuit. Prototypes had been spotted under BMC Trailcrew team riders Aaron Bradford and Tobias Woggon at previous stops on the EWS tour, with Bradford piloting his to a fourth place finish in Winter Park, Colorado. The Trailfox series was first introduced in 2007 in the form of an aluminum framed bike with carbon seatstays and 120mm of travel. Since then, the travel has increased, bumping up to 140mm of travel in 2008, and now, for 2014 the Trailfox TF01 is available with a full carbon frame featuring 150mm of travel and 29” wheels. BMC will also be offering the Trailfox TF01 with a carbon front triangle and aluminum rear swingarm, along with a full aluminum version. All of the frames share the same geometry and suspension configuration.
• 150mm travel
• 29" wheels
• 67 degree head angle
• 435mm chainstay length
• 142x12mm thru-axle
• Internal cable routing
• Weight (claimed): 27.1 lbs
• MSRP as shown (without pedals): $8999 USD
• Full aluminum version with full Shimano SLX: $3999 USD
Going into this project, BMC's product designers and engineers had the goal of increasing the capabilities of the Trailfox, taking it past its trail bike origins and into the realm of a true all-mountain or enduro race bike. After extensive testing of various wheel size and geometry configurations, BMC decided that short, 435mm chainstays, a 67 degree head angle, and a relatively long top tube in conjunction with 29 inch wheels would give them the ride characteristics they were searching for.
The TF01 uses BMC's APS
Once the geometry numbers were settled upon, there were still frame design challenges to overcome, including where to mount a front derailleur. Front derailleurs have long been the bane of 29ers, as the position of the rear wheel, particularly on a bike with short chainstays, makes it difficult to find clearance to fit the derailleur without it rubbing on the rear tire. To avoid this, BMC moved the lower portion of the seat tube forward and mounted the derailleur directly to the rear swingarm. Riders going sans front derailleur can remove the direct mount and replace it with a clean looking cap that bolts to the swingarm.
Other standout frame features include the internal cable routing, an item that has become increasingly common, but BMC's execution is particularly well though out. The cable entrance and exit ports are large enough to make cable changing easy, and the cap design ensures that the cables will stay in place without any rattling on the frame. An integrated downtube protector shields the carbon frame from rock impacts, and ISCG mounts allow riders the option of running a chainguide. BMC has also developed their own chain device that can be mounted onto the chainstay protector. In keeping with the race-oriented design, a full size water bottle will fit on the medium and large size frames, and a smaller bottle can be mounted on the size small. Even though the new bike uses bigger wheels, the frame weight of the full carbon version comes in at a claimed 2490 grams, 40 grams less than last year's 26" version.
The TF01 uses BMC's APS (Advanced Pivot System
) suspension design which uses two short links to attach the rear swingarm to the front triangle. The design is intended to use chain tension to prevent the suspension from compressing due to pedalling forces, while at the same time being able to remain active and absorb impacts from trail obstacles. Sag indicators are printed on the upper link to simplify shock set up – simply adjust the sag until the white lines are aligned and head out for a ride. Ride Impressions
We were able to put in three solid days of riding on the Trailfox TF01 in Whistler, British Columbia, which included racing in round five of the Enduro World Series. There aren't many places in the world better suited for bike testing than Whistler, a location with no shortage of properly rowdy terrain to take the Trailfox on. Our lime green XX1 Trailcrew edition of the TF01 came specc'd ready to race – SRAM's XX1 drivetrain handled shifting duties on one side of the handlebars, while a remote for the stealth routed 150mm RockShox Reverb dropper post managed seat height on the other. Fox takes care of the suspension on the Trailcrew edition, with the new Float X air shock on the rear and a 34 Float CTD up front. Shifting was crisp and snappy, with no mis-shifts or dropped chains at any point during our time aboard the bike. The Float X shock performed admirably as well, working tirelessly to absorb the thousands of rocks and roots we rode over and through. We did experience an odd top out a few times with the 34 Float, which was noticeable after preloading and then popping off a jump, but it occurred sporadically and we didn't have time to investigate it fully.
Stability at speed is the standout trait of the TF01 – even when rocketing down fireroads strewn with softball sized rocks the TF01 didn't flinch, charging along without any discernible frame flex or speed wobbles. This stiffness does mean that increased trail feedback reaches the rider, despite the bike's 150mm of travel. To compensate for this we ended up running the bike on the softer side of the recommended settings, but the bike still had a ride feel that wasn't as plush as we would have expected. For racers, this isn't going to be a detriment, as responsiveness takes precedence over having a super-plush ride, but riders looking for a bike that can make rocky trails seem like they've been flattened and covered in shag carpet may find it difficult to achieve that feeling with the TF01.
Steep corners were where the long top tube / short stem combination truly came into play, making it possible to keep weight over the front wheel without feeling too far in front of the axle. This combination was also helpful on sections where the trail followed the path of least resistance and went straight down the fall line, with the extra top tube length making it easy to find a balanced position without hanging too far off the back end of the bike. Pinkbike's Take:
|The TF01 is a worthy successor to the previous bikes in BMC's Trailfox line, a stouter, more robust offering capable of competing at top level enduro races. A take-charge riding style is necessary to truly eke out every bit of potential, but that's a reasonable characteristic given the bike's intended purpose. We fully realize that the price of the TF01 puts it out of reach for many riders, which is why the fact that a well equipped full aluminum version is available for half the price is appreciated, giving privateer racers a chance to have the same geometry and suspension design as those with deeper pockets. The aluminum version still doesn't fall into what we'd consider 'budget' pricing, but it is on the more attainable side of the spectrum. - Mike Kazimer|