Each of Transition’s new 2018 models were waiting for me in a garage when I met up with some product managers for a ride at the close of this past Crankworx. But I’ve had my eye on the 140-millimeter rear travel, 160 front, 29-inch Sentinel since I first heard about its noteworthy, acronym-worthy SBG geometry. So I spun my pedals on and we headed out.
The trail of choice shall not be named, but it’s a steep, rocky, root-tangled masterpiece not far outside of the park. The pedal up was mostly fire road, but for good measure, we ducked into some singletrack for a section of punchy, techy torture. For that terrain, a 140-millimeter 29er just might be the perfect tool to climb with, as long as it’s done right. Transition’s Horst-style Giddy Up linkage and the newly refined Giddy Up 2.0HH have been doing Transition right for a while now, but the 76.3-degree seat angle on my large-sized Sentinel was something quite new to me. The very similar Yeti SB5.5 has a more elegant, active pedaling dynamic, but its seat angle is nearly three degrees slacker. The Sentinel sat me in a higher, more sensitive part of the suspension travel. And in addition to keeping the suspension active, that seat angle made the Sentinel possibly the most powerful climber in the 140-millimeter category I’ve ever ridden.
When we got to the top I reminded myself that the Transition reps were more familiar with the terrain of the Pacific Northwest than I was. So I opted for the back of the pack, and we dropped in. The 140/160 chassis of the Sentinel is remarkably versatile. Though it can’t quite float through the kind of madness today’s enduro-inspired 29ers can, it certainly will keep you safe if you try. And when the terrain allows, it invites you to choose the line you want and ride it the way you want. It was fun enough that I actually forgot it was made of aluminum, not carbon.
My takeaway from the Sentinel was about to simply be the same as any other mis-matched mid-travel 29er until I began testing the theories behind SBG. Tucking the front wheel slightly further under the steering axis is intended to offer more traction. And putting the wheel almost directly under the handlebars should give the rider a greater advantage in fighting forces that might knock the steering offline.
The effects are immediately noticeable. On any other bike I rode while at Crankworx this year, I found myself feeling timid in corners. Especially in rough, natural terrain and through the many blown-out berms in the park, I always felt my front wheel threatening to slip away when on traditional offset forks. And more than once, it did. But on the Sentinel, I was motivated to trust the front wheel more and more. Early in the ride, while I was still keeping my weight too far back, I still had more reliable traction up front than I was used to. It encouraged me to put more weight on the front wheel. I was able to carry more speed and line up better out of turns than on a traditional bike.
SBG may be the next step in this rapid geometry evolution our bikes are experiencing right now. Even its approach to frame sizing challenged my understanding of what’s right and wrong in bike design. I opted for a large because I’ve been comfortable on 475-millimeter-reach bikes in the past. And the 500-millimeter XL seemed ludicrous. But after riding both, I found that ludicrous reach actually felt perfect in conjunction with the rest of the SBG concept. If you get a chance to ride one, be ready try one with a longer reach than you’re used to. It might convince you that SBG isn’t Some Bullshit Gimmick.