In the past five years, mountain bikes have come a long way. We've gone through two different wheel sizes, various axle width variations, drivetrains that have gained two extra clicks, and the slow death of the front derailleur.

Bike geometry has also evolved. Each month, we meet another super bike that's longer, slacker, and lower than its predecessor. These new era geometries inspire confidence at speed, but Transition argues that they suffer at slower speeds and on flatter terrain. The culprit is the front wheel, which sits too far ahead of the rider.

Transition Sentinel Geometry

The new Transition Sentinel, which was teased here
, is based around the SBG concept.​

To maximize the benefits of these new era trends, Transition believes fork offset needs to change. A shorter fork offset brings the front axle rearward, moving it under the rider. Combined with the shorter stem lengths that are now popular, you gain better front wheel traction.

The entire concept is called Speed Balanced Geometry. It consists of five key dimensions: frame reach, head tube angle, seat tube angle, stem length, and fork offset. Most brands have figured out that longer frames, slacker head angles, steep seat tubes, and shorter stems are better, but now the race is on to figure out fork offset. Press play to learn more.

For Transition, the key to the whole concept is balance. They are trying to better center the rider between both wheels, which will improve front wheel traction, and place them in a more confident riding position.

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