The new Session turns up the speed with a stiffer frame, race-focused geometry, and a livelier ride with an updated suspension design optimized for air shocks. Standard builds come with 27.5 wheel set-ups. But Trek is also offering all the benefits of new Session on a 29er chassis. Offered in limited quantity as a frame and fork package, Session 29 brings faster-rolling big wheels to the downhill scene.
Rachel Atherton gives an overview of the key features of the new 29er DH bike.
More Aggressive Geometry
Updated race-focused geometry is the least visible change to Session, but it’s the one that riders will feel immediately. This is where the Athertons and World Cup racing had the most influence. The reach grew by about 20mm on each size, putting the rider in a more aggressive position on the bike. The chainstays stay on the longer side to match the increased front-center length and keep the bike stable at speed, and also allowing it to plow through the rough stuff without getting the rear end hung up. This is a clear case where shorter chain stays are not necessarily better with the stability and speed demands of the current World Cup DH courses.
Another way Trek increased the bike’s stability and cornering prowess is by giving it a slacker head angle and a lower bottom bracket. The Session is now 10mm lower and sports a 63-degree head angle.
Hoping for a slightly different head angle? The Session features an easily adjustable head tube angle, but it’s not the creak-prone adjustable type. The bike ships with zero-offset cups installed, but it also includes a set of 1-degree-offset cups that can be installed with a forward or backward angle for an additional 1 degree of head angle adjustment in either direction.
Like other Trek full-suspension bikes, Session also gets further adjustability with Mino Link, which offers another half degree of head angle adjustment, as well as about 8mm of BB height adjustment. Between the Mino Link and the adjustable angle headset, riders can dial in their head tube angle to anywhere from 62 degrees to 64.5 degrees depending on the course or their personal preference.
The Session still works great for crushing laps on the bike park jump lines. The Session is primarily sized by reach (not top tube height), which means that park riders can size down to get all of these suspension and stiffness improvements but with a more playful fit. Long top tubes that are desired in the World Cup DH circuit may not be ideal for the fun lines at the bike park so the rider can simply find the size that is most playful for them.
A complaint sometimes heard about DH bikes is the ride feels “dead.” It is sometimes so capable that it squashes most trail obstacles and fails to deliver feedback or fun to the rider, squashing even jumps and features. Trek has worked to address this with suspension changes.
One of the most visible changes to the Session is the new Fox Float X2 air shock. What’s not so visible is the Float X2’s redesigned internals, which were developed on the same timeline as the Session. Trek’s Suspension R&D team worked closely with Fox to optimize the new bike and shock together in a high-performance package with more flexible tuning options than ever before. Updates to the new DH-focused Float X2 include progressive instead of digressive valves and enhanced spring characteristics, which complement the new Session’s lower leverage ratio and longer shock stroke.
These changes to the frame accelerate the shock’s compression speed and introduce higher spring and damping forces for a given amount of wheel travel.
All of that translates to the rider as a livelier ride with more control and more support, especially in the midstroke, where the suspension works the hardest. With the damper doing more of the work and dissipating more energy through the midstroke, the shock gets much more predictable bottom-out resistance for better control on even the biggest hits. The suspension is also more responsive at the beginning of the stroke, allowing the bike to respond to smaller bumps, so it tracks the ground better and improves grip.
More responsive, stiffer frame
Another visible change to the new Session is the absence of Full Floater. Trek previously used Full Floater as another means of tuning suspension characteristics. With the massive improvements in air shocks, including more tuning features like air pressure, spring rate, and spring volume, they can now trade that Full Floater tunability to gain more strength and stiffness in the frame while saving weight and maintaining plushness. So the Session is still one of the lightest DH frames available, but now it’s even stiffer, so it’s more responsive in and out of corners, and it holds a line through even the roughest, gnarliest terrain.