BMC’s Trail Fox has gone through many iterative changes over the years; increases in suspension travel and subtle tweaks to frame construction and geometry have been par for the course. But for the next model year the mountain bike is being reborn, with some revolutionary changes centered around 29in wheels.
While Specialized might have been the first bring a 150mm travel carbon 29er to market, in the form of the Enduro 29, it appears the designers at BMC did their homework as well. The Swiss company redesigned the Trail Fox around 29in wheels after extensive comparative testing.
Click through the image gallery on the right for more details.
The BMC engineers had to get creative to keep the Trail Fox 29’s chainstay length to 435mm (17.1in), just 5mm longer than for the Enduro 29. In fact, BMC’s approach to cheating chainstay length is not so different from Specialized’s. The front derailleur on an Enduro 29 mounts to a plate, dubbed Taco Blade, which bolts onto the chainstays.
BMC’s dual-link design uses an upright brace connecting the seat- and chainstays. Adding a direct front derailleur mount to this vertical brace also allows the seat tube to be designed without consideration for a front derailleur.
In the case of the Trail Fox 29, this allows the seat tube to meet the down tube forward of the bottom bracket; the forward positioning of the seat tube prevents the rear tire contacting the seat tube during full compression. The repositioning also allows the lower link to be moved forward of the bottom bracket, shortening the chainstays.
A plate covers the mounting bracket and keeps things tidy when running a 1x drivetrain
Geometry and frame details
In addition to reworking the frame to accept larger wheels, BMC engineers sought to make the Trail Fox 29 lighter and lower than its predecessors. A medium TF01 29 frame has a claimed weight of 2,490g, 40g lighter than this year model. Compared to a 2013 26in Trail Fox, the top tube is 45mm lower, improving standover clearance; the bottom bracket drops by 8mm as well.
The Trail Fox 29 has a 67-degree head tube angle and is intended to be used with forks with 51mm of offset. According to BMC, this keeps the trail figure in line with the 26in version. All three bike sizes (S/M/L) have relatively long reach measurements and are intended to be paired with short, 55mm stems for optimal handling.
As with their shorter travel 29ers, the company paid close attention to keeping the head tubes short and the stack height low, to keep the handlebar height from creeping up higher than it has to.
It’s somewhat disappointing that the Trail Fox 29 is only available in three sizes. BMC does plan to extend the size range for some of its more popular full-suspension models in the future
BMC also developed a clever modular internal cable routing system with removable plates, to allow riders to configure cables to their liking. The system uses full length housing. All the cables enter the frame through ports on either side of the head tube and exit the front triangle through a port on the underside of the down tube.
Short head tubes and clean cable routing on the Trail Fox 29
In addition to these innovative features, the Trail Fox 29 comes with the usual array of frame standards found on trail and all-mountain bikes – it has a 1.125in to 1.5in tapered head tube and a BB92 bottom bracket with ISCG 05 chainguide mounts, and uses a 142x12 rear thru-axle.
Why convert to the 29er format?
Why did BMC choose to design its all-mountain/enduro race bike around 29in wheels? Aren’t 650b (27.5in) hoops supposed to rule the 150mm travel category these days?
According to BMC frame engineer Jonas Muller, the company tested the merits of all three wheel sizes. Company engineers built test mules in 26in, 650b (27.5in) and 29in versions and trialled them back-to-back on the same course. “The 29er had the greatest performance gains over the other wheel sizes for the criteria we were looking at,” said Muller.
BMC’s test data comparing 29in, 26in and 27.5in wheels in varying conditions
What to do with a 150mm 29er
The 150mm travel 29er category of bike is relatively new, with only a handful of players. The Trail Fox 29 is intended to be an all-day trail bike or an enduro race machine depending on how it’s built up.
The TF01 29 is intended to be a go-anywhere, ride-anything bike
For 2014, BMC will offer the top-of-the-range TF01 29 in two build kits. For all-day riding there’s the standard TF01 29, which features a full XTR build with a double crankset, Float CTD shock and 150mm travel Fox 34 TALAS 29er fork. It rolls on DT Swiss XRC 1350 Spline wheels with a Continental Mountain King tire up front and a faster rolling X-King in the rear.
For enduro racing, the TF01 29 comes in a Trail Crew edition. It shares the same frame as the all-day bike but sports SRAM’s XX1 group, a 150mm travel Fox 34 Float fork and a Fox Float X piggyback shock. It rolls on XM 1501 Spline wheels and Continental Mountain King tires on both ends.
The Trail Crew edition of the TF01 29 is built to withstand the rigors of enduro racing
Both bikes get internally routed RockShox Reverb seatposts and come with 750mm-wide flat carbon handlebars developed by BMC specifically for these long travel 29ers.
Claimed weight for the complete TF01 29 is 12.2kg (26.8lb). The Trail Crew edition sees a slight increase in weight to 12.3kg (12.9lb). The asking price for both bikes is incredibly steep – the TF01 29 will retail for US$11,999/€8,999, and the Trail Crew edition is only slightly more palatable at US$8,999/€6,999. UK pricing has yet to be announced.
Thankfully, there are several versions of the 2014 Trail Fox 29 that come with much more realistic price tags. There are also versions with carbon front triangles and aluminum rear ends, as well as a full aluminum bikes that should have broader appeal. The entry level TF03 29 has a full aluminum frame, Shimano SLX components, Fox suspension and DT Swiss M1900 Spline wheels – it will retail for US$3,999/€2,999.
We look forward to throwing a leg over the bike in future, to bring you a full review.