Transition Sentinel 2025: First Ride Review+

Transition Sentinel: 29er seeks adventurous riders for mutual outdoor fun. Sleek, sexy and BMX-y. 160mm up front, 150mm out back.

Roving reporter Tim WIld tries out a 2025 Deep Purple Transition Sentinel Carbon XT in Large size with Shimano XT build, Assegai on the front, DHR II rear, no Cushcore.

• Brand: Transition Bikes
• Product: Sentinel
• Price: $6,199
• From: Windwave
• Tested by: Tim Wild for a month

Dusty photos by John Shafer

Pros

• Super-nimble ride feel for such a large bike
• Better shock mount
• Flip-chip for mullet set-up

Cons

• Needs to be locked out to climb well, or have time spent on dialling the rear shock
• Might take some work to get the correct sizing
• Seat clamp bolt could be recessed for weather protection

I may be a bit biassed; I love the way Transition bikes look. I know there’s all kinds of advantages and benefits to offbeat frame design, and I’ve enjoyed riding plenty of  bikes with frames that look like CAD malfunctions, but Transitions all look like beefed-up dirt jumpers, and it’s such a simple, elegant, distinctive design. I’m a fan. 

Does this bike keep that playful promise, or get bogged down in the complexities?

This is a bit more of an extensive first-ride review than any of us usually get to do. If we’re lucky, a first ride is a couple of hours on our local trail, or a bikepark lap, but I’ve had this bike for nearly a month, and taken it on epic natural descents from 10,00ft, hard-packed jump trails, brutal rock climbs and twitchy steep rock rolls – on mud, grit, sand, slickrock and lava.  [Not in the UK then! – Tech. Ed]

Rest assured I gave this thing a thorough workout. 

Nuts and bolts

Transition has been selling Sentinels since 2018 – when most enduro bikes were 27.5, and the long-travel 29er was far from standard. Seven years in production is semi-serious for any brand, so there’s clearly a fanbase.

But have they just monkeyed with some trivial details so they can justify a new bike launch, or is this actually worth your time, attention and money?

Subtle but valuable

There’s no sea-change headlines here. 160mm fork. 150mm rear travel. Still looks like a Transition, rides like Transition, feels like a Transition. I’m happy about that – there’s a distinct feel to their bikes that I’d be disappointed to miss. Slack head tube angle? Check. Big standover? Check. Short-ish chainstays? Check. 

But while the changes aren’t revolutionary, they are useful. The new flip-chip makes it easy to switch to mullet, and my guess is that would be great on this bike. I didn’t have a chance to try it out myself, but one glance at the geometry will tell you that this bike would be even more playful and manoeuvrable with a 27.5 rear wheel. 

No more dirtbox

There’s no depression in the frame under the shock mount anymore, so dirt and water won’t pool there, and there’s just enough space to push a small brush or rag in to clean it out. For a UK rider, that’s a serious issue. I’d still prefer a rear suspension design with the shock under the top tube, but that’s my problem.  

Baguette serious

No need for a fanfare here, as frame storage is almost de rigeur on bikes these days, but this is a nicely-designed upgrade. Lots of room – enough for a medium French stick loaf – and the cables are properly hidden and wrapped so they don’t reduce storage volume or get ripped out by your greedy hands or a stray tubeless spike. 

Less shocking

I’ve ridden plenty of enduro-sized 29er bikes that are set and forget for both climbing and descending, but the Sentinel definitely has two modes – climb with a locked-out shock, descend with it open. It’s a reach to the shock itself too – no lever on the bars – so it’s probably going to drive some people nuts, but I think the effort’s worth it. Locked-out, it’s a way more stiff and nimble climber, but it’s not harsh or awkward. The sporty geometry allows for a lot of jumps, twists and hops even in that stiffer mode, particularly on technical climbs, and it feels light and energetic. 

The longer pedal sections are fine too. I’m sure a downcounty bike with long reach would prove itself more comfortable in the long run, but I traversed plenty of pedally singletrack in comfort, and never wished for a different bike, even though this Large’s 480mm reach is shorter than my personal bike. 

Plummet from the summit

This bike wants to play. It’s not a bruising, plough-through-anything beast – more of a mischievous goat. It’s a delight to bounce and compress and hop and flick this thing around on the downhills, and it feels incredibly nimble even at higher speeds, without ever compromising on grip or stability – I could put serious weight over the front in tight fast berms and never worry about a wash-out. It’s not conquering or resisting or dominating the trail – it’s dancing with it. It makes for a great descender, because it made me consider every rock, ledge, kicker and bump as a potential feature, and turned even the most mundane singletrack connector trail into a playground. 

Air style

I like my jumping modest, and part of the trail, and as simple as possible, but it’s clear the Transition could fly through as much air as you can manage – the front wheel pops up beautifully, the standover height is huge, and it’s pretty light. So while I’m not going to trouble the flying groms anytime soon, it felt great to pop off the kickers, tabletops and ledges of the South Western trails of Arizona, Colorado and Nevada, and I can tell it would handle the wet roots, slimy puddles and glassy surfaces of the UK with equal gusto. 

Overall

Although I’m arguably a bit partisan here – I’ve always liked Transition bikes – but I honestly loved this Sentinel a lot. My inner BMX kid just wanted to come out and play right away, but with geometry, suspension and design that keeps that feel even on big, nasty technical riding. It’s not perfect – I’d prefer a bit more protection for the frame and pivot bolts for UK conditions for example – but if I were buying my main bike for the next three years, with plans to ride it all over the UK and beyond, this would be a serious contender. 

Transition Sentinel specification

• Frame // Sentinel Carbon, 150mm travel
• Shock // RockShox Super Deluxe Ultimate, 205x60mm
• Fork // RockShox Lyrik Ultimate, 160mm
• Wheels // DT Swiss M 1900 Spline 30
• Front Tyre // Maxxis Assegai 3C EXO+ 29×2.5
• Rear Tyre // Maxxis Minion DHRII 3C EXO+ 29×2.4
• Chainset // Shimano XT M8100, 30T, 165mm
• Drivetrain // Shimano XT M8100, 10-51T
• Brakes // Shimano XT M8120, 203/203mm
• Stem // ANVL Swage, 40mm
• Handlebars // ANVL Mandrel Alloy 35, 800x30mm
• Grips // ODI Elite Flow Lock-On
• Seat Post // OneUp Dropper Post, 210mm
• Saddle // SDG Bel Air 3

Geometry of our size Large

• Head angle // 64°
• Effective seat angle // 78.3°
• Seat tube length // 430mm
• Head tube length // 120mm
• Chainstay // 445mm
• Wheelbase // 1,273mm
• Effective top tube // 605mm
• BB height // 25mm BB drop
• Reach // 480mm

Review Info

Brand:	Transition Bikes
Product:	Sentinel Carbon XT
From:	Windwave
Price:	$6,199
Tested:	by Tim Wild for 1 month

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