Transition Sentinel Carbon Frame

When we reviewed Transition’s original Sentinel back in 2018,  we said that this “is a downhill bike masquerading in trail bike attire. If gravity is your game, and you’re looking for a flat-out destroyer 29’er, the Sentinel should be on your short list.”

At the time, Transition was ahead of the curve in figuring out how frame geometry for this type of bike would progress. With their introduction of Speed Balanced Geometry, they changed the entire industry’s take on short offset forks, reach numbers, and head angles. That Sentinel has stood the test of time, and is just as relevant today as it was at its launch in 2017.

But if they hit the nail on the head with the first Sentinel, what could they have done with a new one? As with the 2020 Scout, this bike is a refinement over its predecessor, incorporating a sexy new design philosophy filled with hard, fast lines and a slew of updates and smart little improvements. Let’s break them down.

Design
You’ll recognize Transition’s updated 2020 aesthetic from the Scout, with angular, large form factor tubing and a more sparse graphic treatment than the previous Sentinel. It is all new, and all carbon; that’s front and rear triangles, as well as the rocker link. At this point, it does not seem that it will be offered in aluminum, which speaks to the upper echelon of bike manufacturing that Transition now finds itself in.

Suspension
Transition has re-worked the kinematics of their “GiddyUp” four-bar suspension to be more progressive than the previous model, giving riders a wider range in how they can make the bike feel. Do you like a super plush, bump gobbling bike that feels like you’re riding on a cloud? Run 30% sag or more. Want a super poppy, responsive ride that feels more like a down-country bike than an enduro rig? Bump up the air pressure to 25% sag, and you’ll have just that. This change also means that the bike is now coil-compatible (check out the #oncoilhashtag on Instagram and you’ll see what Transition thinks of coil sprung shocks), which we’re certainly happy about. The simplicity and consistency of coil-sprung suspension, along with the DH intentions of this bike, make for exciting prospects.

Geometry
The original Sentinel was longer and slacker than previous bikes, which turned a lot of heads. With that bike, Transition hit a sweet spot, and they have not deviated much on the new model. Reach stays about the same across the board, head angle goes from 64 to 63.6 degrees, and top tubes get a hair shorter due to the even steeper seat tube angle. We agree that this style of all-mountain/enduro bike will settle at these sorts of numbers - getting any longer or slacker has diminishing returns, and reduces the fun-factor.

Along with steeper seat angles (77 degrees on average - they vary on each size - up from 76.4), an un-interrupted seat-tube allows riders to run extremely long seat-post droppers. A 5’9” rider can now run a 200mm post on a medium frame, and small and extra small riders can run seat-posts longer than 100mm.

Details
Small details like in-set, ribbed chainstay protector and updated, more weather resistant pivot hardware speak to the attention to detail that Transition has put into this frame.

Sporting almost full Tubes-In-Tubes technology, (now WITH internal routing), it’s an extremely clean looking frame. Transition has opted to leave the rear brake external, which we are grateful for. Having to uncouple a brake hose from your lever body to change it is a major pain. Other minor items, like full size water bottle fitment and the ability to run up to 2.6” tires are sure to keep even the most discerning rider completely happy.

In 2018, riding the 35 lb aluminum Sentinel, we concluded that the bike was “a downhill bike masquerading in trail bike attire.” We loved it, but it was hard to think of it as a total quiver killer, since its heft and at-the-time revolutionary geo edged it just out of do-it-all territory. But with the 2020, version 2 of the Sentinel, Transition has smoothed out all the rough edges (while, paradoxically, giving the frame sharp edges!) and refined it into a weapon that is versatile and capable enough to be your sole bike.