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FiftyOne Assassin review

2 Dec 2021

Variable geometry gives the FiftyOne Assassin an ace up its sleeve when it comes to versatility off-road. One for all occasions

Cyclist Rating: 
Variable geometry • Responsive • Highly adaptable
Mounting points will be overkill for some

Over the past six years, FiftyOne has forged a reputation for making some striking custom road bikes in its native Ireland, but the FiftyOne Assassin marks a departure for the framebuilder. First up, it’s a gravel bike; second it’s made in Asia. But there are compelling reasons for this.

Gravel bikes are made from increasingly complex tube shapes that can’t be fabricated with the tube-to-tube method FiftyOne employs in Dublin. To hit the gravel high notes, a large-scale factory had to be employed to execute the company’s ideas, of which there are quite a few.


The Assassin fits both 650b and 700c wheels, with a maximum tyre size of 47mm in both cases; both chainstays are dropped to afford tyre clearance, preserve stiffness and allow space for double chainsets as well as 1×.

Rack and guard mounts abound, including up the fork legs; under the down tube is a rubber bash guard; the fork has internal routing for a front dynamo. It’s all bob-on the latest gravel trends, and yet there’s one thing that marks the Assassin out as unique (to the best of my knowledge): radically changeable geometry, courtesy of flip chips.

Flip chips are alloy inserts in the dropouts that can be removed and ‘flipped’ – from a high to a low position at the fork, or across three different fore-aft positions at the rear end.

Flipping these inserts changes the position of the wheel axles relative to the frame (because it’s the chips that locate the thru-axles), thus a few flourishes of an allen key sees the Assassin go from 75mm trail in the ‘low’ position to 87mm trail in the ‘high’ position, and 1,047mm wheelbase in the ‘short’ position to 1,062mm in the ‘long’ position.

In a sense this is nothing new – the GT Grade and Rondo Ruut gravel bikes have flip chips in their forks – however this is the first time I’ve seen front and rear flip chips on a gravel bike, and although the changes seem tiny – mere millimetres – the effect is significant.

Flippin’ ’eck

All things being equal, longer trail and wheelbase means slower but more stable handling, while shorter trail and wheelbase means faster but twitchier handling. It’s why a size-comparable road bike has around 58mm trail and 990mm wheelbase, whereas an enduro mountain bike might have 130mm trail and 1,200mm wheelbase. What the Assassin is trying to do, then, is to do it all.

Want to sell your possessions and bike round the world? Go long wheelbase and long trail, the best type of geometry for stability and comfort over heavily laden miles. Want to ride fast, technical trails? Go short trail and short wheelbase to shoot through those chutes. That’s fine in theory, but does it work?

Simple answer: yes. Swapping between the Assassin’s extreme geometries was like going for a coffee with Dr Jekyll, then downing pints with Mr Hyde. The long, relaxed setup was cruise ship stately, but changing to short trail, short wheelbase left the Assassin like a possessed tractor.

To best describe it: bowling down a steep, rutted track in long setup I just held on, relaxed and leant back a touch. But repeating this in short setup I had to concentrate hard, almost fighting the bars as the ground tried to knock the front wheel off line. But if that sounds undesirable, it’s not.


While long setup might be at times sedate (hence why FiftyOne says long setup works so well for bikepacking) it also allows the Assassin to roll over gnarly stuff without landing like a shopping trolley off a skate ramp.

And while short setup might sound unruly, the payback is being able to ride twisty singletrack at speed, which on this bike is hugely rewarding. Short setup also means the Assassin is much more adept on the road than it otherwise might be, climbing without the languidness of a longer, slacker bike and taking turns with nippy aplomb.


Yet while the Assassin is highly adept at many things, it doesn’t excel at any one. For example, it is competitively light at 8.91kg but it could be a chunk lighter without the extra mounting hardware and flip chips. Although in short guise it’s much more responsive on the road than in long mode, it could be even shorter – there are gravel bikes out there with trail figures under 60mm and wheelbases very close to 1,000mm.

These aren’t criticisms, just observations, and ones that cement the point. This is a jack-of-all-trades bike, and where gravel is concerned that’s only a good thing. Want to bikepack to Scotland then race Grinduro? The Assassin will oblige. Want to keep up with the chaingang? You might need different tyres but the Assassin can do it.

The greatest gift of gravel is variety, and to take advantage you need utility and versatility, which the Assassin has in spades. Plus it delivers on the thrills too.

Photography: Patrik Lundin

Pick of the kit


Sportful Evo jersey, £110, Sportful Fiandre bibshorts, £115

I’ve long been a fan of Sportful for its no-nonsense approach, and this latest offering doesn’t disappoint. The Evo jersey is light, breathable, has a racy cut and has pockets that don’t sag, and I’m a particular fan of the ‘raw cut’ sleeves (ie, no hem).

The Fiandre bibshorts have been around for a while now, and in this ‘light’ guise they lose the thicker brushed lining of their NoRain Fiandre sisters but retain the windproof and water-resistant status. The short’s cuffs are also raw cut and use neat silicone grippers to keep them in place.

• Buy the Sportful Fiandre Light bibshorts from SigmaSports


Go road

If classic road is more your thing, FiftyOne makes road bikes to measure from its workshop in Dublin. Framesets start from £6,500, and are available in rim and disc.

Stand out

The Assassin is available in two stock finishes, but for an upcharge starting from £600 (based on complexity), FiftyOne offers custom finishing, such as on this Rothmans Racing-inspired road bike.


Frame FiftyOne Assassin
Groupset   Campagnolo Ekar
Brakes Campagnolo Ekar
Chainset Campagnolo Ekar
Cassette Campagnolo Ekar
Bars Enve Gravel
Stem Enve Road Carbon
Seatpost Enve Road Carbon
Saddle WTB SL8 saddle
Wheels Campagnolo Shamal Carbon Disc, WTB Riddler 700c × 45mm tyres 
Weight 8.91kg

All reviews are fully independent and no payments have been made by companies featured in reviews

£3,299 (frameset)