The Trek Session 29 can officially claim to be the world’s first ‘production’ carbon 29in downhill bike. Availability is stated as October this year.

Telemetry testing by Gee Atherton resulted in a time that was four seconds quicker than the 27.5 Session over a two minute track. The telemetry also showed that at no point on the track was the 27.5 faster than the 29 Session.

The first prototype

Trek Session 29 Carbon need to know

• Frame only
• 190mm travel
• OCLV carbon only (no aluminium offering)
• 62.1°-64.4° head angle (via alternative ±1° headset cups and the Mino link flip-chip in the rocker)
• 157mm back-end
• Fox Factory 40 FIT RC2 fork 190mm with 58mm offset
• Same front triangle as the Session 27.5
• 450mm chainstays
• A “limited quantity” will be available
• $5,000 (frame, rear shock and fork)

Following on from being beaten to the punch by Santa Cruz and their V10 29er reveal, and Danny Hart winning Ft Bill BDS on a 29in wheel Mondraker Summum, the only surprise about the Trek Session 29 Carbon is that it wasn’t announced even earlier than now.

We’ve yet to ride one so we’ll restrict this write-up to a tech spec description. We might chip in a bit of comment here and there though!

The last prototype

Designed for air shocks

The new Session 29er is designed with air shocks in mind. The Session Carbon 29 comes with a trunion-mount Fox Float X2 Air rear shock.The frame has dropped the full-floater aspect (the lower shock mount is now fixed). Contrary to what internet opinion may say, the move away from full-floater was not done so as to fit the larger wheel size into the frame (you’ll note the new 27.5″ Session is no longer full-floater). The move is to make a stiffer frame and because air shocks have improved.

Trek: “the Float X2’s redesigned internals […] were developed on the same timeline as the Session. Trek’s Suspension R&D team worked closely with Fox Racing Shox 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 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.”

Despite this though it appears that the Athertons will be running coil shocks on their World Cup bikes for the foreseeable.

Trek Session Carbon 29 geometry

It uses the same front triangle as the 27.5″ Session which is presumably why the 29er Session ends up being actually slacker than the 27.5″. Having said that, Trek claim that both the 27.5 and the 29 Sessions work best with the head angle set to 63°.

Geometry-wise, the 29er is tad shorter in reach that the equivalent frame-sized 27.5 Session, Again, presumably due to the tipped-back effect of using the same front triangle but with a larger wheel size.

When will we see it in action at a World Cup?

Good question.

The next World Cup is on June 3-4 in Fort William.

The thing is, Gee Atherton is currently out of action after an injury at the Fort William British Downhill Series.

And it doesn’t look like Rachel Atherton is going to dally with big wheels just yet thanks. She very wisely doesn’t want to upset her considerable winning ways by messing with things.

This may mean that Trek Factory Downhill racers Graeme Mudd and Kade Edwards will be in the considerable spotlight.

No pressure guys!