Transition have really stepped up their game in recent times with the addition of the new geometry setup that has been championed by the likes of Chris Porter at Mojo Rising. This “more out there” setup includes head angle changes, fork offsets and longer-lower bikes.

The all new Sentinel 29er has all these things mated up to some big wheels. Transition call this SBG (speed balance geometry) - a concept that was sprung upon me over a load of beer while sat around a table in Finale. There was big talk of numbers and “the best handling bike ever” that simply had to be put to the test.

This is the aluminium bike as opposed to the carbon version. This was all that was available at the time but it would be the bike that I would choose.

Shape and fit

The size Large sent over from Transition in Bellingham did feel a little small to start with but after throwing a tape over the bike it measured up well. There is a 475mm reach, 64 degree head angle and 1247mm wheelbase - these are good numbers that should translate to a stable and easy ride.

The standover height on these new bikes really is low too with a 700mm height on the large the frame keeping it well and truly out of the way. The aggressive, 800mm wide RaceFace bar gave a comfy cockpit area and helps make the bike feel even larger when in the riding position.

Suspension and chassis

The same classic Transition chassis look remains with a four bar linkage driving a Fox suspension platform on this model. The rear linkage, constructed from aluminium, is a single piece unit that has welded-in bracing for increased stiffness. That linkage drives a trunion mounted Fox Float DPX2 rear damper that pushes out 140mm of rear travel.

Upfront is another Fox goody with the 44mm offset 160mm travel Fox 36 Float Elite fork, which keeps to the stealth look that the bike has going on. It’s worth noting, the RockShox equipped model has a 42mm offset.


Transition Sentinel spec

Fork Fox 36 Float RC2 Performance Elite 
Shock Fox DPX2 Performance Elite 
Handlebar RaceFace Atlas 35 (800mm X 20mm) 
Stem RaceFace Aeffect R (40mm) 
Headset Cane Creek 40 Series 
Brakes SRAM Code RSC 
Shifters SRAM X01 Eagle 
Crankset SRAM Descendent Carbon (30T, 170mm) 
Rear derailleur SRAM X01 Eagle  
Cassette SRAM XG 1275 (10-501) 
Chain SRAM GX Eagle 
Seatpost RockShox Reverb Stealth 1X Remote 
Saddle ANVL Forge Stealth Cromo 
Hubs E*Thirteen TRS+ 
Rims E*Thirteen TRS+ 
Tyres Maxxis Minion DHF & DHR II 2.3 EXO 3C 
Chain Guide OneUp ISCG05 Top Guide

With some serious kit bolted onboard the Sentinel, there is no doubt that this is aimed at the enduro crowd. There’s the new SRAM Code brakes, some Maxxis DHF and DHR tyres, Eagle gearing and E-13 hoops all coming together for £5,049. It’s a great looking bike.


First impressions were not as great as I had expected, there was something just not hitting the mark for me.

The bike was going head to head with my favourite bike of current times the Orbea Rallon, two bikes that are trying to do the same job but in different ways. One carbon and one alloy but both long, low and slack 29” enduro weapons.

After one ride I seemed to have nailed the issue on the head and changed up the wheelset for a more robust option. The E-13 wheelset that was specified didn’t seem man enough for the job in hand and I had bent the rear wheel at the first time of asking.

Changing up the hoops to a Roval set made a massive difference. The Sentinel really benefits from being ridden hard and the faster the bike is pushed the more you get from it.

The “Speed Balance Geometry” also seems to be doing its job, having the playful feel that I would look for in any bike but traction at all times. The fork offset being at 44mm, as opposed to the standard 51mm for a 29” bike, gave a much nimbler feel when getting into steeper more technical terrain.

With only minor issues and after some setup, the Transition Sentinel was an absolute blast to ride. It’s always a tough call when pitching a bike against something that is as good as the Rallon but it has come out of the corner fighting. With a simple wheel swap the bike was transformed.


So some small issues with the Sentinel. Firstly was the fact that the bikes came fitted with inner tubes. This is such a tiny thing and it would be simple to setup tubeless (before the rear wheel exploded) but it is always a nice touch when buying an expensive bike to have this done for you.

The wheelset is the second thing. As mentioned previously this is not the end of the world and simply changing these out for something a little more robust is perfect. In this case some carbon rimmed Roval wheels were fitted and made such a difference.

The paint work looks amazing when unboxed. Such detail. But make sure if you’re buying one of these that ALL areas that will rub, chip or scratch are well protected and covered - as nice as it looks the paint is thin and marks very easily.


Not the perfect product but one giant leap in the right direction. The simple lines and design of the Transition Sentinel really have made some headway on the lineup. This bike sits perfectly above the Smuggler with an aggressive stance and a solid feel. The carbon chassis model may be a tad lighter but all in all I found the aluminium chassis a super fast and fun bike with a clean and silent ride.