The full carbon Transition Sentinel frame looks super slick, and ticks just about every box in the ‘modern geometry’ checklist

>>> Best full suspension mountain bike in 2019

Transition Sentinel need to know

• American DH-focussed mullet bike with 140mm rear travel and a 160mm fork
• Properly modern with long, low and slack numbers, optimised for Transition’s short fork offset SBG (Speed Balanced Geometry)
• Super-smooth lines on the full carbon frame – right down to the rocker link and stays
• Beefy 4-piston Code brakes to handle the Transition’s bad intentions.

Transition is based in Bellingham, Washington in the top western corner of the USA. Renegade trails laced with jumps and berms thread through its dank, steep, fern-covered woods and it looks like a fantastic place to ride. And after riding the Sentinel, and knowing this rugged fall line terrain is accessible from the company’s HQ, it’s soon clear where this 140mm 29er is designed to excel.

But before we get into that, let’s take a closer look at the bike. Reach is properly generous in each size, standover clearance is as good as it gets, and there’s a huge wheelbase on this size Large ‘trail’ bike at almost 1,250mm. A reduced offset fork reins this in a tad, and is integral to the SBG (Speed Balanced Geometry) design ethos by making the steering feel calmer. Note the bike category’s deliberately in inverted commas, since this 64° machine is way more aggressive than your standard trail bike.

FOX DPX2 Performance shock delivers 140mm of travel via four bar set-up

One gripe with Transitions in the past has been relatively poor UK value. This GX Eagle model costs the best part of £5k, but (sadly) that’s par for the course for a 2019 carbon rig of this calibre, and this is actually hundreds of pounds cheaper than equivalents like the Santa Cruz Bronson or Evil The Offering with similar kit.

So while it’s not cheap, it’s decent value and even better when Transition’s specification scarcely misses a beat and you don’t have to change a single part. The 10-50t Eagle cassette can winch up any hill and the Wide Trail Minion 3C tyres come in 2.5in front and 2.4in rear casings.

Swooping lines make for a slick-looking carbon frame

There are sorted ODI Elite grips, SRAM Code R disc brakes, and good handlebars and stem too. Cash savings mean heavier, slower-rolling, Stan’s Flow S1 rims and Fox Performance suspension, rather than the coveted Kashima coated Factory kit, plus an old-style, Reverb plunger remote I thought I’d seen the back of.

Like other Transitions I’ve tested, the Sentinel won’t win many sprint or hill-climb challenges. Thanks to the steep seat angle, the seated climbing position is great, but there’s less urgency and a duller feel at the pedals than plenty similar travel bikes. Around sag, the four-bar suspension compresses under power, so flipping the Fox DPX2 compression lever for more support when climbing, or even punching along flat trails, boosts efficiency.

The Sentinel punches well above its weight for a 140mm-travel bike

The 140mm rear suspension doesn’t have an extremely high level of sensitivity off the top either, so the suspension feeds back noise from smaller bumps and chatter on naggery, steep and tight terrain at lower speeds. Tyre grip leant over downhilling or in terms of traction climbing is still more than sufficient though.

That said, the rear suspension moves smoothly through its travel with good support against rider loads without ever bottoming harshly. The chassis remains composed and balanced, and the shock stays impressively active tracking bumps, even when panic grabbing big handfuls of rear brake when lots of other bikes falter and lose effectiveness.

SRAM Descendant 6K DUB chainset

Once you open up the throttle and let the bigger wheels charge, the Transition really comes alive. Look far ahead, point the front wheel down, let it roll and the super-stiff chassis will get you there without flinching. Stable without being cumbersome, the Transition holds some mean lines across root-flecked off cambers, and despite the long wheelbase, it’s animated without feeling sketchy, and easy and intuitive to chuck about.

The mismatched travel doesn’t upset balance, and the Fox kit at both ends syncs well and maintains speed over the dirtiest terrain. Smashing through holes, or (most notably) landing really deep off a huge step down, the Sentinel absorbed big hits incredibly smoothly, shrugged its shoulders and surged onwards; to the point of a few ‘what-the-hell’ moments where I couldn’t believe the speed and calmness on tracks I know really well.

ODI Elite grips are a quality choice but dropper remote is a bit of a relic

This ability to keep pace once gravity takes over is pretty outstanding for a 140mm bike, and makes it a very engaging rig you can push hard and fast on (if you don’t prioritise getting to the top or along twisty singletrack in a major hurry).