History of the Session 29
It's never been much of a secret that Trek was working on a 29” downhill bike – pictures surfaced as far back as 2009, but it was always presented more as a concept bike, rather than something intended to go into production. That is, until now. The Session 29 is finally a reality, with a frame, fork, and shock package set to become available this October.
The bike has a full carbon frame and 190mm of travel, and will be available in three sizes: small, medium, and large. The same frame features that are present on the Session 27.5 are in place on the Session 29, and, in fact, the two bikes share the same carbon front triangle.
Trek Session 29 Details
• Intended use: downhill
• Rear wheel travel: 190mm
• Fork travel: 190mm
• Wheel size: 29''
• OCLV carbon frame
• 62.1º - 64.4º head angle (adjustable with headset cups, Mino Link)
• 12 x 157mm rear axle
• 450mm chainstays
• Sizes: S, M, L, XL
• MSRP: $5,000 USD (frame, fork and shock)
• Available: October 2017
Trek began considering a 29” wheeled downhill bike in 2009 when they created an aluminum framed bike with a 64.5-degree head angle, 440mm chainstays, and 180mm of travel. That project convinced Trek's designers that the larger wheels held plenty of potential, but unfortunately there weren't enough components available at the time to bring the bike to market.
More recently, Cole Picchiottino was enlisted to test out newer versions of the frame. Picchiottino is an elite-level racer, but he's also a key test rider for Trek, someone who's willing to head out on unproven equipment and report back his findings, even if that could potentially mean a less-than-stellar race run. That's something that a top-end World Cup racer wouldn't be willing to do; at the highest lever of our sport, winning is the absolute focus, and switching things up in the middle of a race season simply isn't in the cards. With Cole, however, it's a different story, and he was able to provide invaluable feedback to Trek as the potential for putting the bike into production began to increase.
In fact, Trek almost pulled the trigger on rolling out a 170mm DH 29er two years ago, one that was based on a 165mm bike they'd worked on with Cole, but other projects ended up taking priority and the big wheeler remained on the back burner. That delay may have been a blessing in disguise – had Trek took the leap at that moment, the lack of available components could have caused that bike to flounder, rather than coming in on the crest of this year's wave of other downhill 29ers and components. During that time period, they released the 150mm Slash 29, a bike that provided even more motivation to get a DH 29er out into the world.
Buy what exactly makes 2017 different from years past? Why are we now seeing scores of 29” downhill bikes appear under the sport's elite riders? The biggest reason is that there are now components available that can handle the rigors of World Cup DH racing. Tires from Schwalbe, Maxxis, and Bontrager, among others are on the way, and with a major player like Fox stepping in with a production 29” downhill fork, the stage has been set for a major shift in the world of downhill. Fox 49
The 27.5” Fox 40 deserves credit for helping push the development of 29” downhill bikes forward. As it turned out, with a little modification to the fork arch it was possible to fit a 29” wheel, something that hadn't been possible with the 26” version. That ability to start experimenting with big wheels was the spark that helped light the fire under Fox to start looking into creating a 29” wheel-specific 40.
Once the word was out the Fox would be going to production with a 29" DH fork, there was no shortage of phone calls from race team managers and bike manufacturers trying to procure one for pre-season testing. Even for those lucky enough to snag a fork, there was one more hurdle to overcome - the fork uses Boost 20x110 spacing, which meant that for those without dedicated hubs, adapters had to be created to shift the rotor over into the correct position.Session 29 Geometry
Trek's headquarters are in Waterloo, Wisconsin, but they also operate a suspension R&D facility located just north of Los Angeles, California. Housed in a small industrial park, the facility is headed up by Jose Gonzalez, Trek's director of suspension development. This is where prototypes are sent for additional testing and analysis, a sort of skunkworks laboratory for bringing concepts to life. It's also where the most current iterations of the new Session 27.5 and Session 29 were housed, so I headed down to spend time on each of them before their public debut.
Day one was dedicated to back-to-back testing using LITPro, a highly accurate GPS tracking device that's about the size of a deck of playing cards. Originally developed for the motocross world, LITPro's high accuracy makes it possible to break each lap down into smaller sections that can be used to compare speeds and times with much more precision than you would be able to with a typical GPS. The track we'd be riding was the same one the Atherton's had been on a couple of months prior, one that contained the ideal mix of tight berms, rock gardens, steep sections, and high-speed straightaways.
With the LITPro velcroed to my helmet and a scouting run out of the way, it was time to start laying down some top-to-bottom lap times. My first laps were on the new Session 27.5, which is an impressive bike in its own right. It didn't take long to get comfortable, and soon I felt right at home diving in and out of steep turns and plunging into the track's awkward rock gardens.
With three laps on the Session 27.5 under my belt, it was time to switch over to the Session 29. I'll admit that I was a little bit nervous about what would happen when I hopped onto that XL 29er. In my head, I had visions of rocketing down the trail, unable to turn or control such a seemingly massive bike. I'm confident in my bike handling skills, but I'm no World Cup racer, and being allowed to ride the Session prototype felt like being allowed to hop into the driver's seat of a Formula One car.
All of that faded away once I dropped in - the difference between the two bikes was noticeable from the very first turn, and any trepidation I felt instantly dissolved, replaced a sense of giddy excitement usually reserved for lottery winners or kids in candy stores. I could tell that I was going faster, but the bike felt calmer and smoother than the 27.5, and there was less need to make little micro-corrections to the steering.
The straight line speed of the 29er is impressive, but the way it felt in steep corners was even better. There's was no skittering or wobbling, just a rock-solid, locked in feeling that allows you to let off the brakes and use the bike's momentum to carry you through the turn. Looking at the LITPro data confirmed this sensation — the calm handling of the 29er allowed me to brake less, which in turn led to faster cornering speeds. The data also verified that the Session 29 was faster than the 27.5” bike – to the tune of nearly 5 seconds on a 2:20 course. On both bikes, my times improved on each lap as I got more familiar with the course, but when I switched back to the 27.5” bike from the 29er my times slowed down, illustrating that the bigger wheels made a significant difference.
It's faster, feels more stable, and is wickedly fun to jump and to slap through corners... So what's the downside? Honestly, the only slight knock against the Session 29's performance that I encountered over those two days of riding was the fact that that the rear tire buzzed my shorts a couple of times. Once was while I contorted myself in a strange position in order to make it over an awkward hip jump that probably wasn't built with downhill bikes (of any wheel size) in mind, and the other was when I got too far off the back in a rock garden.
The 'bzzz' sound of rubber hitting polyester let me know that I was a little too close for comfort, and I was able to adjust my position in time to keep my backside safe. The closer proximity of the rear wheel is something to be conscious of, but I honestly don't see it as being much of an issue – I bet after a few more days of riding, the number of instances would be reduced even further once I got fully in tune with the bike. Fastest 27.5" Lap vs. Fastest 29" Lap