When the British brand lead by Dominic Mason launched the first version of the Mason Definition in 2015, disc brakes and all-round geometries were still a rare site in the racing-bike circuit. Now Mason is launching a revised version of it — the Definition 2. Can the new incarnation of the Definition affirm its four-season dominance?

Mason Definition 2 | 8,51 kg | 3.110 €

First act — The story behind Mason Bikes and Dom Mason.

Dom decided to leave a secure job at Kinesis UK in 2015 to start his own adventure. The new brand carries his name. The risks involved were huge: the “Just doing something” approach doesn’t really work anymore especially when you consider the scale of his new project. Dom was designer and brand-manager at Kinesis for 15 years. Are these the ideal conditions to start a new venture on your own? Maybe if you have the right team around you. Dom wanted to focus more on the design side of things have a trusted person taking over the welding. That’s why he teamed up with two frame builders from Italy who understand his needs and implement his ideas with the highest quality standards.

Alone in the forest, far away from stress, noisy cars and …
… the rush hour madness. We say: …
… the forest is our highway on our way home!

Although it doesn’t seem too long ago in 2015 the road-bike sector was very different indeed. Disc brakes were a rare sight on racing bikes and endurance-bikes were mostly a slower clone of sportier racing rigs. Dom Mason’s mantra is “Make – Progress”. This clashes with what some of the bigger manufacturers are doing with their products. Mason doesn’t want his bikes to be a warmed up version of an old recipe for success but rather a true icon of real progress.

Pleasant colour matching and clever integration solutions
Now also with a 12-mm- through axle!
Seatpost and clamp are also from Mason

And you should be able to ride them all year round. Four seasons, all weather conditions, one goal: The performance shouldn’t depend on the weather. This is a meaningful consideration, if you’re a fair-weather rider you’ll only get to ride your bike a few days a year if you live in the UK… Four seasons. This stands for change, change and development. The weather is changing and so should our way of thinking about winter- and bad-weather bikes – this is Dom’s conviction. It should be your “good bike”, the one you can always ride. And not just your “n+1” mantra.

Golden hour on the Mason with 30 mm-wide Tubeless Schwalbe G-One Speed-tires

Second Act, the Mason Definition 2 with SRAM Rival 1x spec.

The “Mason Bikes” concept made perfect sense and so the Definition and the Resolution were born. But the market is changing fast and what was considered exotic in 2015 has now become standard. True to the motto “Make – Progress” Mason’s team is introducing the Definition 2 — an upgrade of their “4Season” workhorse. The frame is still handmade in Italy but the post-mount brakes and quick-release axles have been replaced by a flat mount standard and 12mm thru-axles. These details ensure a cleaner frame and improve the bike’s braking performance. What has long been recognised in the MTB community is sometimes still considered revolution in the roadie world. Dom Mason’s self-designed Aperture carbon fork was also upgraded with flat-mount brakes, thru-axle system and a more generous tire clearance — actually up to 33 mm if you’re happy to ride without a mudguard and otherwise 30 mm — still plenty considering we’re talking about a racer. Another neat detail are the interchangeable thread-plates on the fork which can be easily replaced in case of damage.

Mason Aperture 2-fork with interchangeable thread-plates
The shifting performance of the SRAM Rival 1 feels a little spongy
The braking performance on the other hand is always predictable and reliable

The heart of the Mason: the frame of the Definition 2 – is made in Italy with a custom Dedacciai aluminum tubeset and features all of the typical traits of an all-road bike. Tire clearance? Check! Mounting points for mudguards and pannier rack? Check! Popular axle-standard for a quick wheel change or replacement in case you left your axle lying on your driveway again? Check! Adaptable inserts for brake hoses and gear cables? Yup! The system with adaptable inserts is compatible with both electronic and mechanical groupsets and makes for a very versatile bike and allows you to carry out hastle-free upgrades

  The harmonious design and the beautiful colour-schemes are spot-on.

The 1x SRAM Rival groupset reduces the shifting to it’s essentials

Our Definition 2 came with a SRAM Rival 1x spec. It’s true that 1 x setups have widely been accepted — even in the peloton now! — and still they’re quite an exotic sight on all-weather racing-rigs. We like it! The SRAM Rival groupset also includes hydraulic SRAM Rival brakes which offer a very predictable modulation. The Definition 2 comes with a Deda Zero 1 cockpit and a Deda headset that match the tubeset superbly and an Mason branded seatpost and seat clamp. The wheels are the result of a collaboration between Mason and Hunt Bike Wheels – the MASON x HUNT 4 Season Disc wheels. These include 30 mm-wide Schwalbe G-One Speed tires and a 10-42 cassette. British manufacturer Fabric supplies the saddle and bar-tape and rounds off the harmonious package.

See ya later, the party carries on off the beaten track
The good-natured handling loves small detours
„Look Mum, no hands“

The Mason Definiton 2 in Details

Shifting SRAM Rival 1
Braking SRAM RIVAL Disc
Tires Schwalbe G-One
Weight 8,51 kg
Price 3.110 €

Third Act: Testing the Mason Definition 2

– “I report on the victory on tarmac.” If the Definition could talk this would probably be one of the few things you’d hear from it. It wants you to take it on rough roads. It maintains its cruising speed extremely well whether you’re riding on the road or on disconnected forest paths. The heavy-ish system weight and chunky 30 mm Schwalbe G-One tires require some effort to bring the Definition up to speed but once you get there the bike feels stable, smooth and good-natured on pretty much everything that stands between you and your destination. The Definition 2 feels a little sluggish uphill but it’s also true that Dom Mason didn’t try to build a bike for mountain stages. The balanced character of the bike is the strongest attribute and greatest strength of the Definition — and it makes it a superb all-rounder. It feels composed at all times and inspires confidence even at high speeds even when the roads are wet. We didn’t deliberately choose to test the Definition in wet conditions but the rain sure made for a more interesting testing environment.

Good morning concrete jungle!
… but I’d rather go back to the countryside

The Definition reacts to fast direction- and lane-changes and rides well on all sorts of terrain — jumping from the tarmac to the adjacent forest path requires almost no steering adjustments and little acceleration. The motto is: “Just get over here, it’s all good.”
The Definition follows direction changes quickly but you’ll need a little extra strength to change lanes.
Situations where you suddenly have to avoid obstacles can lead to “close calls” — or even to quick prayers prior to hitting a pothole that just opened in front of you around the corner. With hard decelerations the SRAM Rival 1 brakes feel reliable and predictable but can’t quite keep up with the modulation and braking-power of their bigger siblings — the SRAM Force and the SRAM Red. The shifting is reliable but feels a little spongy when the chain is under load; again the Rival can’t quite match the performance of SRAM’s Force and Red models. One of the advantages of a 1x drivetrain is the absence of a front derailleur which makes the whole system a lot simpler. However in order to cover the entire gear-range without a front-derailleur the gear jumps has to be a lot bigger. This isn’t necessarily a bad thing and during our test we never felt like we were running out of gears. However it can sometimes be difficult to find the right gear for your optimal cadence.

Mason Definiton 2 Geometry

Size 50 52 54 56 58 60
Top Tube 532.8 mm 537.4 mm 551.5 mm 561.1 mm 581.3 mm 586 mm
Chainstays 420 mm 420 mm 420 mm 420 mm 420 mm 420 mm
Head angle 71,5° 71,5° 71,5° 71,5° 72° 72°
Steering tube 130 mm 140 mm 155 mm 170 mm 180 mm 190 mm
Seatstays angle 74,5° 74,5° 73,5° 73,5° 72,5° 72,5°
Reach 380,6 mm 382,5 mm 383,0 mm 388,0 mm 394,7 mm 396,8 mm
Stack 543,3 mm 552,8 mm 565,5 mm 579,7 mm 591,1 mm 599,1 mm

Conclusions Mason Definition 2

With the new version of the Definition, Dom Mason created a bike that can cope with rough surfaces and still appeal to a broad range of riders. At € 3,110, the Mason Definition 2 is slightly more expensive than most equivalent bikes from the competition — for example the BMC Roadmachine X. Having said that, for your money you’ll get a hand-built bike from the tubeset to the components. The superb package is complemented by a balanced, confidence-inspiring handling and is guaranteed fun even when the road gets ugly.


– Confidence-inspiring handling
– Composed on every kind of surface
– clevere details on frame and fork
– Quality of the frameset


– Not a featherweight
– Tires quickly reach their limitations
– Spongy SRAM Rival 1x shifters

For further information head over to masoncycles.cc

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Words: Photos: Benjamin Topf