2025 Transition Sentinel
FIRST LOOK REVIEW

2025 Transition Sentinel

Photos Skye Schillhammer
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Initially launched to great acclaim as a 140mm 29er trail bike in 2018, the Transition Sentinel is now entering its third generation. A few years after V1, the brand from Bellingham rolled out the second iteration with a travel bump up to 150mm and subtly tweaked geometry. At the time they were making room at the lower end of their travel lineup and pushing it closer to the 160mm Patrol. Since then, the Patrol got mulleted and they released the Spire as the longest travel 29er, so the latest Sentinel now sits squarely in the 29er lineup between the 170mm Spire and 130mm Spur.

Transition describes their aim with the new Sentinel as trying to hit a 'sweet spot' and make it just a tad sportier without giving up its ability to manage steep and rough terrain when the need arises. As a brand that avoids hyperbole and tired clichés, they stop short of the exhausted 'Swiss army knife of bikes,' but they also know their customer, and the Sentinel is the bike a lot of riders choose because it can handle the widest spectrum of rides. If you can't or don't want to think about what bike to bring on a trip or buy, the Sentinel will never be the wrong choice, short of an XC race.

As a rolling testament to how good the two prior generations were, the 2025 Transition Sentinel yet again sees subtle updates, however taken altogether they make for a very modern, polished package and V3 is quite different from V1.

Here's the new 2025 Transition Sentinel in a nutshell:

  • 150mm travel frame / 160mm fork
  • XS gets 27.5" wheels, M through XXL are 29" (but it's also now designed to work as a mullet)
  • Available in Carbon or Alloy including frame only options for both
  • Two build kits in either material: Deore or XT, and X0 AXS in Carbon only
  • Now has size-specific chain stays
  • HTA tweaked from 63.6 to 64
  • Updated industrial design is still reminiscent of the prior version's angular muscularity
  • Leverage curve adjusted to support the rider a little higher in its travel
  • BOOM Box (Burritos Or Other Munchies) in-frame storage; door sits low in the frame, isolated from the water bottle mount (this is a very nice touch)
  • Comes with Fidlock bottle attachment plate
  • Tool mount eyelets on bottom of top tube
  • Lower shock mount geo adjust flip chip (for wheel size changes)
  • Tweaked loam shelf area should retain less water and debris (but also, less loam shelf)
  • Cable ports on both sides of the head tube for use with wired shifting (yay!) as well as easy brake cable swaps for moto/non-Canadian colonials, and supplied inserts to cover unused ports.
  • Mud guard to protect main pivot area

This is probably a good time to mention that since that review I wrote in 2021, I still have my V2 Sentinel. I've ridden it a bunch, and I still love it. Call it bias, call it deep familiarity, but I was primed to like V3 and the fact they didn't make big changes only helped things further.

Geometry

Similar to what we're seeing elsewhere these days, things haven't changed much on Sentinel geo. For the XL I rode, the wheelbase is 10mm longer, the effective ST angle is now 77.9 vs 76.4 on the last version, all head tubes are 4/10 of a degree steeper, chain stays on the XL are 8mm longer but because they're now variable, they're 6mm shorter on the XS. Just about everything else is the same. I loved the geo on the V2 XL - it fits my long torso perfectly, it's stable as hell but doesn't handle like a sled, still feels like a trail bike but the axles feel like they're always in a good place and the bar just says 'belly up, cowboy.' Transition knew they had it about right, and they didn't mess with anything here.

What about Mullet Geo?

Transition is not going to offer a mixed wheel option for sale, but for those that want to run it, they advise using the Low flip chip setting for 29", and high setting to run a 27.5 rear. They also didn't supply a geo chart for mullets, but if you're wondering what happens to the numbers when you mullet the rear wheel, here's what they had to say: "This goes for all sizes with the exception of the stock 27.5 XS. Reach shrinks by 4mm per size, BB height is lower by 6mm. HT and ST angles are 0.4 degrees slacker. CS is 2mm shorter."

2025 Transition Sentinel Geo diagram

Transition uses sensible effective STA measurements.

2025 Transition Sentinel Geo chart

The geo chart is based on dual 29" wheels, with the geo chip in the low setting, 64* HTA.

2025 Transition Sentinel 19

We climbed some steep stuff, too, and the slightly steeper effective STA agreed with my dimensions.

2025 Transition Sentinel 26

Chuckanut in prime conditions a few days after some rain in early August.

Riding the 2025 Sentinel

I was invited to Bellingham the week after Crankworx to spend a few days on the new bike. I rolled into town the night before and met up with Lars Sternberg at Trackside - a social mtn biker's paradise of dirt jumps, food trucks, and Kulshan brewing kiosk all a few minutes away from downtown. I just love the feeling in Bellingham. Whether you're in town for the Saturday farmer's market or taking in live music in the main square from a patio it's got this laid back crunchy friendliness. Nothing is forced, no one's too cool to say hello. Anyway, bikes.

The next day we gathered at the Transition Outpost to get sorted out. Here's how my setup turned out:

Setup

RockShox Super Deluxe Ultimate: body weight is recommended start point, so for me that was 195 psi, giving the desired 30% sag. HSC and LSC near the middle.
RockShox Lyrik Ultimate 160mm: 85 psi, LSC 5 clicks out from closed, HSC 2-3 clicks out, no spacers (as stock).
Maxxis Assegai 29 x 2.5 3C EXO+ MaxxTerra front tire: 22 psi
Maxxis DHR II 29 x 2.4 3C EXO+ MaxxTerra rear tire: 25 psi

Usually media camp rides put you in a situation where you get your test bike set up fast enough not to be the last one ready - and then, once you feel like you have the bike in a pretty good window, you call it more or less done and get riding. You also often have the benefit of knowing you'll get more time to tweak the bike to your liking at home, but that was not the case here as I didn't go home with a test bike. On the plus side, we were a small group of only two media and even though we rode a ton, there was time to tweak. Plus, we rode the bikes for a day and a half to get used to them, and then did some mild bracketing on a trail we rode quite a few times, so it was an ideal way to get a feel for what was going on.

The Riding

On day 1, after going over bikes and setup, we just pedaled right out of the Transition office's parking lot and over to Galbraith. As a side note, if you're ever visiting Bellingham, go check out the Transition Outpost - it's their offices and a beautiful showroom that's also stocked with great beers and other drinks, a full shop where you can have your bike worked on, and a food truck with Vietnamese fusion food that is mega tasty. There were all kinds of non-riders stopping in there for a snack and a drink on the patio. The vibe is chill, the people are cool. They got it right.

Off to Galby. Up we went for a few hours of a mixed bag of awesome, from the eye-watering high speeds and multiple G berms of Blue Ribbon (a trail Nico Vink built) to a few steeps, a bit of bench cut, and some flow on Pump Track (+ Actual) and a few more sprints through the short trails of Galbraith. I needed about three more runs down Blue Ribbon to really get the feel for it - it is so fast and the berms are so big that you can carry speed like a bobsled on rails, but I didn't log any A-Line time this summer. On one little steep line, I felt so comfortable I hardly saw the hole in the middle of the 2-step line, but I felt it. The bike stayed gathered but an off-balance moment would have led to a big decompression and a brief moment in orbit. No worries, though - consistent with the V2 I know well, the Sentinel seems designed to help you hold on when you take too big a bite of steak and helps you get through it without choking.

Lunch at the Outpost, then we loaded into the van and headed off to...shuttle a trail I don't think I can talk about. Steep, sustained loam. Deep stuff, mostly soft but with some holes that made for some physical riding. Many bikes would have felt good there, but not all of them would have had us all in attack mode like that. It was a cacophony of yelling and laughing, and we all ended up with necks caked in loam, which is usually a gold seal of great riding.

2025 Transition Sentinel 15

There's also a RockShox Super Deluxe Ultimate on my personal V2 Sentinel and it was a noticeable improvement over the last gen X2. I was happy to see this shock on the 2025 Sentinel.

The Importance of Bracketing

On day 2, we did 4-5 shuttle runs on Chuckanut and took the opportunity to do a little bit of bracketing. Lars told us he'd been experimenting with running the shock's compression settings both fully closed and really liked the way it was riding. I may not ride like Lars, but he still thought I'd feel what he did. I'd been riding the shock pretty much in the middle of the range on day 1 and for the first 2 laps on day 2 and the Sentinel felt good almost everywhere. Before trying Lars' idea, we decided to open the shock all the way first. That gave the back end a less composed feeling - I was searching for traction and not finding enough of it, and it also felt a bit harsh. We stopped pretty quick and went all the way in the other direction, and closed the high and low-speed compression circuits all the way. And...whoa! What I felt now was a whole bunch of support that I could push into and use that energy to reach for doubles or, if I made a mistake or missed, I still felt like there was more traction and therefore margin for error. The back end felt calmer, and as a result I could spend less time focusing on technical thoughts and just ride the bike. I was a bit quicker and smoother, and felt myself using less energy, even as we racked up a few more laps.

I saw Chuckanut through new eyes after putting in all those laps. I'd always liked it up there but it's so much more fun once you start to remember at least half of the turns and blind risers. It's a good one to remember for bike testing.

2025 Transition Sentinel 28

Because the V3 feels and rides like an iteration of its predecessor, I find it easier to form opinions of the bike after 'only' two days - albeit pretty solid ones (especially day 1). There are bikes in this category that climb better, but the Sentinel is no slug - in fact it climbs better than ever, thanks to the tweaked leverage curve that held me higher in the pocket and responded a little more swiftly to inputs. When descending, the harder I pushed and the more engaged I was, the better it rode. Aggression and intensity were rewarded with control and precision. But part of what I love about the V2 I own is still true here. Plenty of trail and enduro bikes with aggressive geometry only reward you when ridden hard, but the Sentinel's positive traits don't disappear if you are having a chill day, they're just not as prevalent. That's a perfectly acceptable compromise, but one that makes the Sentinel a great choice for riders with a variety of skill levels.

2025 Transition Sentinel BOOM Box 1

I didn't get a chance to play around with my BOOM Box at home and put clever things in there like mushrooms, or gummies, or gummy mushrooms.

2025 Transition Sentinel BOOM Box 2

Transition did a nice job with the latch and door assembly, and the tool and accessory pouches are nicely shaped and work well.

Spec and Pricing

I'm not going to spend a lot of time talking about the components on my test bike - mainly because there were no surprises and everything worked well. After two days, you wouldn't expect anything less. Transition makes sensible spec choices throughout the line, and I think the pricing reflects a good balance of performance and value decisions. The Carbon XT trim level I rode costs 6,199 USD / 8,399 CAD which is enough cake that you shouldn't have complaints. Full XT, RockShox Ultimate level Lyrik and Super Deluxe Ultimate suspension, a 240mm OneUp dropper post, and Maxxis rubber - it all checks out. If there's a vulnerable spot at this price, it's the DT Swiss M 1900 wheels, but only by weight - it should be a workhorse wheelset with easy-to-service 370 hubs.

In contrast to some other recent releases, there are no limitations with this frame as far as cable/wireless drivetrain choices. And if you're curious about building one up from parts, you can do that - the 2025 Sentinel is available as a frame only in alloy and carbon. As usual, pricing on frames only isn't the greatest value proposition, but if you're in that position, the Sentinel frame is a stunner with lots of sensible features and well thought out design.

2025 Transition Sentinel Pricing

None USD CAD
2025 Sentinel Alloy Deore 3,299 4,499
2025 Sentinel Alloy XT 4,499 5,999
2025 Sentinel Carbon Deore 4,899 6,599
2025 Sentinel Carbon XT 6,199 8,399
2025 Sentinel Carbon XO AXS 7,899 10,799
2025 Sentinel Alloy Frameset 2,199 2,999
2025 Sentinel Carbon Frameset 3,399 4,599

Since it was first launched, the Sentinel has represented exactly what you want in a trail bike, and the latest version continues the tradition: it’s happy to pedal and climb all day long if you need it to, but it’s all still in service of the descent. And when that time comes, the Sentinel delivers. Even if you get in a bit over your head, it has you covered. It won’t replace the big bike for some, and it isn't pretending to, but it does a great job as a stand in. As far as trail bikes go, the Sentinel keeps its spot high on my list of favourites.

2025 Transition Sentinel

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Comments

heathen
+2 Dogboy Curveball

Sad the chip doesn't keep the geo the same. Also odd not to show a geo chart for the mixed wheel setup

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dogboy
+1 Curveball

I'm glad I'm not the only one who feels this way. I like the ability to switch between 29 and MX wheels and the geo being preserved seems like the way to go. Anything else just seems like a flip-chip half measure.

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Jotegir
+1 Curveball

Norco, on their most recent batch of Sights and Optics had to do a lot more than a flip chip to maintain geometry - different rocker links and shock mounts! It leaves me to wonder if certain suspension designs are forced to choose between big changes (like Norco) or differing geometry to change that rear wheel size.

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Curveball
0

My Rallon came with a different shock yoke to switch between them and maintain geometry. I recently used that to switch it to MX after too many butt bites with the 29er. I'm very much loving the change.

Reply

pete@nsmb.com
+1 Tjaard Breeuwer

I'm not certain but think it may be because they're not selling it as a mullet and want to avoid confusion.

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dolface
+1 AJ Barlas

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dolface
0

This comment has been removed.

GrundleJ
+2 Pete Roggeman BarryW

Great write-up @Pete Roggeman!  I appreciate your quantitative feedback and your more casual comparison when it's suitable to get the message across. 

You mention that "There are bikes in this category that climb better, but the Sentinel is no slug."  What bikes would you say climb better in this category?  As a Michigander that visits areas all over but does 90% of my riding on the short up/downs that most of Michigan provides if like a FS bike that I can push into some sketchy stuff and pick the "less traveled" line through the rough stuff but also that I can pedal uphill all day.  Finding something that fits the bill and is available in alloy or steel has been a search that I've not yet found a winner in.

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pete@nsmb.com
+2 GrundleJ Tjaard Breeuwer

I haven't ridden the new Stumpy EVO but the last gen is one. Spectral is another.

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GrundleJ
0

The spectral is on my radar, but I've largely ignored Specialized over the last few years for personal reasons.  Might be worth having another look.  Thanks!

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araz
+2 GrundleJ Timer

Banshee frames are on sale super cheap right now. Prime or Titan might fit the bill since you want metal

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orrphism
0 Chris D Jotegir

too bad no UDH, need to be able to sell the frame someday

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GrundleJ
0

They use a modular dropout so it *shoud* be easy for them to offer a UDH compatible dropout that fits all of thier Dropout V1 & V2 frames

DaveSmith
+1 Cam McRae

On trend. There's going to be a lot of great options for 150mm/160mm bikes on the market from every manufacturer this season.

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Frorider
+1 Curveball

Geo of the XL is very close to my current benchmark bike (SB 160), but the rear tire clearance issue in the PB review is surprising.

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BarryW
+1 Pete Roggeman

Great first look review Pete! 

That purple color is awesome! And the pricing seems pretty good, and available in alloy? What's not to like?

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pete@nsmb.com
+1 BarryW

Thanks Barry. Yeah the frame and bike availability in alloy, carbon and three colours of each is impressive. I was partial to the crisp white but the purple is sweet, too.

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Curveball
0

If you're dead-set on running a 2.6 tire in back, it seems that it's limited to a 2.4. That's about it from what I can tell.

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craw
0

Sounds like a good update! What's the actual seat tube angle (always a relevant deciding factor for XXL bikes)?

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dano91
+3 Cr4w firevsh2o solar_evolution

I think someone mentioned it being about 72 on PB. 

That stack height is still too short for my liking on the XXL. The spire had the same problem.

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craw
0

I've got two bikes with roughly a 77-78' ESTA but one has a 72' ASTA and the other 69' ASTA. 72' ASTA bike fits way better. I could live with a 140mm head tube on XXL. It's nice to have more options. 

My 170 bike has a 1333 WB which is pretty long but suited to task. My 150 bike is around 1310 which feels appropriate. Things get blurry when the shorter travel bike is also very long.

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sospeedy
0

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