Prologue: Skiing 1996
At the 1996 US Junior Downhill Skiing Championships, a then largely-unknown 18-year-old Bode Miller announced his presence by winning three of four events, and placing second in the other. What was most significant about this event other than the arrival of a great talent? His equipment. His weapon of choice? A “shaped” ski, in this case the K2 Four, which sported a much deeper sidecut to add to the ease of turning.
Until that time, shaped skis were a small niche market to most consumers. Especially racers, who perceived them as nothing more than a gimmick to make things easier for noobs, shied away from. Until that day when a young renegade Bode mounted up and took the skiing establishment by storm on a new design. 
Present Day: Downhill mountain bike racing in 2015
Little-known Tucker Kennedy arrived at the 2015 Colorado Downhill State Championships on a new design: The Foes Mixer Enduro. The result? First place in one of the two most competitive junior downhill races in the country. To be fair, Tucker is a skilled and accomplished rider, but finding the top of the podium at such a major event was something new. The crazy-new mixed wheel bike was his partner for his ascendance to the pinnacle of his division. 
The Foes Mixer Enduro: The newest mixed wheel design.
The uniqueness of the Mixer comes from the mix of wheel sizes: 29″ up front and 27.5″ in the rear. Mixed wheel bikes are nothing new, and even as recently as the 29er wave, numerous manufacturers from garage boutique welders to the giant Trek were making 69ers with a 29″ up front and a 26″ in the rear, in hopes of getting the best of both worlds in one bike. However, either due to legitimate performance concerns or just plain old consumer reluctance to try something nonstandard, the concept never took root and seemed dead. However, in his relentless pursuit of performance, MIke Vidovich of Timberline Cycles had been experimenting with almost every possible combination of wheel widths and diameters. After finding what he believed to be performance that truly exploited the best of both worlds rather than compromising them, he approached Brent Foes with the idea of creating the perfect frame to take advantage of the 29/27.5 mix and fully realize its potential. 
The Opportunity
When I got the offer to be one of the first to write a full review of the Mixer, I was more than a little excited. I was, like most would be, skeptical of the mixed wheel concept, but I try to keep an open mind and I rarely turn down an opportunity to try something new. I was very curious to see if the reality would be anywhere near the claims presented. Of course, the fact that Tucker had just taken first in Colorado went a long way to ease my pre-ride concerns. What made this even more interesting is that the Mixer Enduro is a 6″ travel enduro rig, not a downhill rig, even raced with a single crown fork, and yet it had found the top of the podium in a downhill race. Either this bike had an incredible performance range, it was miscategorized, or there was some kind of a fluke here. I anxiously awaited my opportunity to find out. 
The Foes Mixer Enduro by the Numbers
The Mixer frame is fabricated in the USA by Foes from hydroformed aluminum. So what we have here is a mixed wheel bike with a 29″ front wheel and a 27.5″ rear wheel mated to a frame with 160mm of rear travel (adjustable to 170mm), optimized for a 160mm fork. The standard Mixer Enduro head angle is right in the middle of enduro-land at 66.5 degrees, although Mike has tweaked it as much as a full degree in either direction.
Bear in mind that enduro bikes are generally built as pure 27.5ers and larger wheels usually require steeper angles, so theoretically 66 degrees on a Mixer should ride slightly slacker than it would on a standard enduro bike. Similarly, the 13.65″ bottom bracket height is close, but a little on the high side compared to most enduro bikes–but again, that location is no doubt influenced by a little extra rise from the large front wheel. 
The smaller rear wheel allows for a shortish 17.6″ chainstay and a 46.75″ wheelbase–a little on the short side for a 27.5″ enduro bike, let alone one with a 29″ front wheel. My size large has a 24.5″ top tube length and a 29.5″ standover–again, right in my comfort range for enduro riding.
But in looking at the bike and the numbers, it becomes obvious that the significant differences generated by the mixed wheel design render a simple look at the numbers next to meaningless. The only way to make any kind of meaningful assessment of this bike would be to spend some time on it: maybe more time than usual, should the uniqueness of the design end up requiring extra adjustment time. 
The Timberline Build Kit
While Timberline will build a bike to any spec, they specialize in custom mixing of quality but reasonable-cost parts to bring high end bikes into a competitive price range. The standard Timberline build for the Mixer enduro comes with a Fox Float X CTD shock, a RockShox Pike RC 160 fork, a Stan’s wheelset (customer choice of Flow or Arch), SRAM’s GX 1×11 drivetrain, SRAM DB-5 brakes, Schwalbe Nobby Nic 2.35 tires, and quality aluminum controls. The Timberline build without dropper post or pedals tips the scales at 29.5lbs–not a featherweight, but not out of line with other bikes in the category. It also taps the bank account at a somewhat-lower level than comparable bikes, at $3,995 MSRP. 
Questions
So as I approach the testing period, I have a number of questions. Most obvious among them is: how will the mixed wheel design perform? Is it truly the best of both worlds, is it a compromise, or is it even less than the sum of its parts? What about that geometry: will that shortish wheelbase reduce stability and will that higher bottom bracket hurt cornering? Will all that aluminum be no fun now that I’ve grown accustomed to carbon.
Actually, the list of questions is quite long. Finding answers should be interesting. I actually have very high hopes, given the bike’s performance on the race course. So will it be a gimmick or a game changer? Stay tuned for the full review, coming soon!
