Transition Sentinel Review (A New Type of Mountain Bike)

With so many companies producing long travel 29ers, the decision of what bike to go with is harder than ever before. The Sentinel is the new long travel 29er offering from the folks at Transition Bike Company. Not only does it offer 160mm / 140mm of travel front and rear, but comes spec’d with a redesigned layout called SBG, or Speed Balanced Geometry. The new Sentinel from Transition offers some of the most radical geometry featuring a slack 64 degree head tube angle, but more on the specifics later.

Transition Sentinel

The Sentinel comes with boost spacing, front and rear, a metric trunnion mounted Fox DPX2 rear shock, and internal cable routing for everything but the rear brake. This is a great feature that will have any mechanic smiling from ear to ear! You can also fit a full size water bottle in all sizes along with a longer length dropper post; 150-170mm will fit in most frame sizes. Additional features such as molded rubber frame protection and updated internal cable grommets help keep the bike quiet while riding.

A radical change from most bikes is the newly introduced Speed Balanced Geometry (SBG). SBG consists of 5 major changes:

  1. Slacker head tube angle
  2. Reduced fork offset
  3. Shorter stem
  4. Longer reach
  5. Steeper seat tube angle.

The combination of all these geometry changes results in a very unique, yet fun bike that will inspire confidence in the most technical of sections. Many companies have been going longer and slacker within the last couple of years, but instead of going slowly with each new model, Transition decided to jump head first into the change and adopt this style on their entire lineup!

Speed Balanced Geometry

First Ride Impressions: 

Climbing was something that I was immediately skeptical about on a bike this large. With the aluminum frame adding more weight, my initial thought was that the bike would be a slug. From the start, the climb was technical and steep featuring a singletrack to the top. After getting comfortable with my positioning on the bike, I started to cruise up the climb with as much ease as a mid-travel carbon bike would. To my surprise, I was able to clear almost all the steep rocks without any trouble. With the reduced fork offset, the front end did not want to slap side to side the way you would expect a 64 degree head tube angle to do so. Considering I left the shock in open mode, the bike had very little suspension bob and seating position was as good as any XC race bike.

Transition Sentinel Review

Keeping my legs in proper riding position with my weight centered on the bike, I made it to the top with time for both Instagram and Snapchat pictures before my co-worker came into sight. Now the fun part...descending! Dropping into the trail, the first section is a steep and fast shoot which the Sentinel was able to handle this with ease and allowed me to carry more speed through this section than ever before. While riding, I was so focused on going fast that I didn't stop to think about what part of the bike was making this possible. However, after analyzing the bikes performance, the head angle and long wheelbase clearly work well together and provide a feeling of stability and confidence in steep and fast sections.


Feeling confident, I went ahead and did the bigger drop on the trail and followed it up by hitting the trail gap. Not a huge drop, but the run in can be a bit sketchy. This was no challenge for the Sentinel, which smashed through the rocks and skimmed the chatter while easily holding enough speed. Considering I haven't hit this gap since the rain, I was very happy to hit it first try on a new bike. The other jumps on the trail were primarily long and low with small lips that send you far. The momentum held by this monster made it easy to launch off anything and provided an extremely enjoyable riding experience.


Overall, I think Transition nailed it with the Sentinel and the new SBG geometry. Not only did I enjoy my ride but am greatly looking forward to trying the other updated bikes in their lineup, such as the Smuggler or Patrol. With a slack head tube angle, long wheelbase, reduced fork offset and steep seat tube angle all playing major roles in bikes right now, Transition has hit the nail on the head. For a bike with this much capability downhill, its climbing traits are impressive to say the least. I expected this bike to shred on the downhill but was blown away with the actual riding capabilities. Insane speed, no loss of turning ability, and all around a blast to ride. If you want a bike that can climb and replace your DH bike (do people still ride those?), I think you should try out the Sentinel soon! I was really impressed with the bike and am looking forward to getting more rides and a full ride review on this monster 29er!

If you're interested in purchasing a Transition Sentinel, please contact us or give us a call at 1-805-375-4525 and we'll be happy to get you on the bike of your dreams!

Transition Sentinel

Transition Sentinel Review

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November 06, 2017

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