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Mason Definition Ultegra Hydro



A fantastically speedy and versatile do-everything bike that's an absolute joy to ride, whatever the weather

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Mason Definition2 is simply a superb machine, crafted with attention-to-detail to give a ride sensation that almost defies logic. It's lively yet relaxed, delicate yet you'd take it anywhere, and is just really fun to ride. I'd never get bored of it, and it puts any other alloy bike I've ridden firmly in the shade.

  • Pros: Comfort, spec, acceleration, cornering, looks, clever design, versatility
  • Cons: The (justifiable) price means it's probably out of reach for many

There's a bit of a story behind how I got hold of this test bike. It was collected by my colleague Stu Kerton from Mason's HQ in Brighton, and he subsequently rode it the 130 miles back home to Wiltshire.

> Buy this online here

Stu's review of the first Definition was highly positive; he liked it so much he actually bought one. In fact, we decided that the Definition2 needed a different opinion this time around, to ensure Stu's Mason love affair wasn't just a personal thing.

I was keen not just to see what had changed, but to find out for myself what made a former engineer who has tested hundreds of bikes get so giddy about a £3,000 aluminium offering that weighs nearly 9kg.


To the casual observer it might look like nothing has changed that much, but the Definition2 has seen some subtle alterations that bring it up to date with the latest and most popular disc brake standards, namely the flat-mount and thru-axle formation. This meant a change to the rear dropouts, which Mason worked hard to design itself with its Italian frame makers – rather than stick on a part from a third-party that might not work with the chainstay design.

Mason Definition Ultegra - rear dropout.jpg

Mason had thought ahead on this and knew it would happen eventually when bringing out the first bike, but didn't want to rush ahead before it had come up with the right solution. The result is a custom part that no one else is using, and the Definition2 is a little stiffer at the rear with the thru-axles, according to Mason.

Mason has also moved the multiport for the rear brake hose from the top to the inside of the chainstay, because the previous placing could potentially lead to water ingress – again a small change, but every little helps. 

Mason Definition Ultegra - rear disc brake.jpg

All Definitions now come with the Aperture2 thru-axle carbon fork with the clever F-Stop Axle system (specced on the later batch of first Definition bikes) and 30mm Schwalbe G-One tyres now come as standard instead of 28mm Continental 4 Seasons, because that's what most people wanted anyway, says Mason.

Mason Definition Ultegra - fork.jpg

You get a set of 1,535g Mason x Hunt tubeless-ready wheels, Shimano Ice Tech 140mm disc rotors and Deda finishing kit, and my test bike came with a full Shimano Ultegra R8020 groupset with compact chainrings.

A new Element Grey colourway is offered in addition to Shutter Black and the Lens Blue on my test bike.


The Dedacciai tubes are hand-selected by Mason, and then sent to independent frame makers in Italy to be built. Mason and its makers maintain a close working relationship, so new designs and innovations are always a two-way thing. The frameset has mudguard mounts as standard, and my test bike weighed 8.79kg.

Mason Definition Ultegra.jpg

To look at it's beautifully finished, with very smooth welds and a vivid paint job that gleams in the sun. I really like the branding on the fork, which adds some colour to an area that's usually quite plain, while the rest of the frame is pretty understated. I'm afraid our photos really don't do justice to the finish, though – my fault for riding the bike before Oli took the photos; I cleaned it but didn't polish it, hence all the smears.

Mason Definition Ultegra - fork 2.jpg

The frame geometry is the same as the first Definition, and in terms of the tube shapes they're unchanged except for a more ovalised down tube – as opposed to round – for better stability. Mason did toy with the idea of altering the geometry to be a bit more aggressive, because a lot of its Definition customers were using it predominantly for club rides, but decided against rather than risk changing the ride feel and all-day comfort it's renowned for.

Mason Definition Ultegra - frame detail.jpg

The Definition2 comes with a 71.5-degree head angle, a 15.5cm head tube and long 42cm chainstays on my 54cm frame. The effective top tube is 55.1cm, the seat angle 73 degrees (similar to a race bike), and 38.3cm of reach is plentiful, so you can get into a racy position on the drops if need be.

Mason Definition Ultegra - riding 3.jpg

All in all it's on the sharper side of an endurance bike, but not a race geometry. The bike looks quite square, upright and relaxed, though it rides anything but – as I was about to find out.

The ride

Most of my test riding was done on rough, muddy cycle path, with occasional scrambles on gravelly roads and also plenty of dedicated training rides on tarmac thrown in – easily over 1,000 miles all in all.

After initially hopping on, I could feel that it was pretty upright and tall at the front, and those 30mm tyres felt like pillows compared with the 25s I usually ride. I wondered if it would just feel a bit too relaxed and ploddy for me, but the opposite was true.

Mason Definition Ultegra - riding 4.jpg

The acceleration and power transfer you can generate through the Definition2 is almost other-worldly, and although I knew of the bike's lofty recommendations it still took me by surprise. It's easily comparable or even better than a lot of the carbon frames I've ridden in terms of power transfer; you really feel that none of your effort is wasted and everything just works in unison.

Bikes with more relaxed head angles can often leave me feeling a bit uninspired, but this is absolutely not the case here – it's properly exciting to ride, and just made me want to go fast.

The BSA threaded bottom bracket and large area around it adds stability and control, and it's a joy to ride uphill, with no creaks or squeaks. Mason says the larger down tube also adds to the stability you feel.

Mason Definition Ultegra - bottom bracket.jpg

I'm not really sure why or how because I didn't make it, but I'm sure the fork really makes a lot of difference to the ride in terms of handling and control. It feels really nippy and springy, yet when you brake it feels incredibly firm and controllable.

Although I wouldn't dare leave it locked up anywhere even in plain sight, it's also perfect for riding through town because of the acceleration you can achieve and the stability. I actually started to enjoy the last bit of my ride home through Bristol city centre on the Definition, and I don't say that lightly.

I made sure to test out the stiffness of the frame and comfort offered from the front end through the many potholes that my local council are kind enough to not bother covering up, and the Definition2 passed with aplomb. No buzz or vibrations that I dread with cheaper aluminium frames, it glides over with ease. The wider tyres and plush Deda RHM 02 handlebar with the comfy new Ultegra brake hoods would have undoubtedly contributed to this, but as a whole package you get a seriously smooth ride.

Mason Definition Ultegra - bars.jpg

Descending and cornering were equally as impressive, and the Definition has a great ability to hold its line.

Brakes & bits

Braking through Shimano's Ice Tech rotors is awesome considering their diminutive size: precise, quiet and responsive. Mason will supply you with 160mm rotors if you really feel the need for something meatier, but I'm pushing 12 stone and had more than enough stopping power on the road.

Mason Definition Ultegra - fork detail.jpg

For '4Season' purposes, I think the Mason x Hunt wheelset provided is perfect – it's tubeless-ready, pretty light at 1,535g, and the freehub even makes a sexy noise. The spokes also have brass nipples with hex heads so you can get precise tensioning, should you hammer them too much. That said, I've ridden them pretty ragged over the test period and they're still running true, so I've no doubt they will last you.

Mason Definition Ultegra - rim and tyre 2.jpg

Fabric supplies the bar tape and its Scoop Shallow Pro Carbon saddle. The saddle won't be to everyone's liking – those who like a wider groove or more padding might want to swap it out for something more plush – but I'd have thought for the majority of cyclists it will be comfortable for long rides.

Mason Definition Ultegra - saddle.jpg

Ultegra groupset

I'm a big fan of the new mechanical Ultegra, as are all of us who have tried it so far at Towers (full review of the groupset coming soon). The shifting is clean and crisp, and the front mech is particularly rapid, which comes in handy for roads that ascend sharply.

Mason Definition Ultegra - front mech.jpg

I also love the brake hoods; my hands never felt uncomfortable even on 80-milers.

Mason Definition Ultegra - bar and shifter.jpg

You're getting the full groupset included here with no cheaper components mixed in. My test bike had compact chainrings and an 11-28 cassette which was welcomed for climbing, but Mason can spec other sizes and ratios on request.

Mason Definition Ultegra - drivetrain.jpg

A very minor cosmetic moan – I reckon the old Ultegra crank would look better on this bike. The fat one here doesn't match the neat slim tubes of the frame in my opinion, and I think it looks better on an aero bike.

Mason Definition Ultegra - crank.jpg

The fact that this is my only criticism of new Ultegra tells you all you need to know about my feelings on it. Unless you've unlimited funds or ride for a pro team, there seems little need to spec Dura-Ace level components for the rest of us now Ultegra is so good. And it's versatile – you can get up to an 11-34 cassette on the back if required.

Other options

You can get the Definition2 with Shimano 105 for less, but unless you agree with me fervently about the crank aesthetics, I reckon the Definition deserves at least an Ultegra-level spec. If you're a SRAM fan you can also get it with Rival 1x (£2,795), Force 1x (£3,130) or wireless eTap (£4.995). A shade under £4,000 gets you the Di2 version of Shimano Ultegra.

There's no denying £2,930 is a big spend, so what's out there in terms of competition? To be honest, it's hard to find anything completely comparable – premium aluminium usually means a race bike, such as Cannondale's CAAD 12 (£2,199 with an Ultegra disc spec), but that's a completely different beast, without the tyre clearance or more relaxed feel.

> Buyer's Guide: 13 of the best aluminium road bikes

Looking at alternative metal frame materials, a titanium Kinesis Tripster ATR V2 with similar do-it-all properties comes in at £1,850 for the frameset. A steel Fairlight Strael 2.0 (review coming soon) is £2,600, and with a lower claimed weight and similar attention to detail with build, tyre clearance and flat-mount standards, this could be one bike that challenges the Definition's all-season prowess.


Overall, I feel the Definition2 is a real triumph and represents the pinnacle of what can be done to date with an aluminium frame. A massively responsive ride, the latest disc brake standards accommodated successfully, and plenty of tyre clearance with no discernible disadvantage other than some weight penalty and, of course, a price premium. But I think you are really getting the best of everything with the Definition2, therefore the outlay goes much further.

With regard to the unchanged geometry: could Mason have been braver, perhaps even offering a more race-orientated Definition2 as well? Practically, that wouldn't have been ideal for a smaller brand, and with such positive feedback for the first, why risk changing it? That was the conclusion Mason came to, and from my experience of riding the bike well over 1,000 miles, I'm glad. It wouldn't feel like a Definition if the comfort, and potentially the smooth running of the new rear thru-axle system was compromised for the sake of very marginal speed gains, so I'll assume Mason knew not to try to fix something that ain't broke.

Mason Definition Ultegra - riding 2.jpg

If I could have one very good multi-purpose bike for commutes, occasional forays on gravel/mixed terrain and training rides, this would be it at the time of writing. N+1 advocates might not agree, but I'd swap my winter bike and five-year-old carbon racer for a Definition2 in a heartbeat given the choice. Any ounce of snobbery I once had about aluminium frames has been well and truly cast aside after a memorable two months with it.

Second opinion

I asked Stu what he thought of the Definition2 on his ride back from Brighton to the West Country (after I'd written this, so as not to influence my opinion). Here's what he had to say:

"From the second I started to pedal away from Mason HQ on the Definition2 it was like being reacquainted with an old friend, and I was definitely glad Mason had decided not to fettle with the geometry and the rear triangle. It still retains that same liveliness and responsiveness of a race bike with the comfort and stability of something more endurance-based.

"One noticeable difference while carving through the descents of the South Downs was the Aperture2 fork. Being thru-axle compatible, there is a firmer feel at the bottom end of the fork legs under really heavy braking compared to that of the quick release original. A minimal but beneficial upgrade."


A fantastically speedy and versatile do-everything bike that's an absolute joy to ride, whatever the weather test report

Make and model: Mason Definition Ultegra Hydro

Size tested: 54

About the bike

State the frame and fork material and method of construction. List the components used to build up the bike.

From Mason:

Dedacciai Performance triple-butted aluminium tubing. Frame hand-built in Italy

Aperture2 thu-axle fork - optimised for wider tyres and mudguard clearance, full carbon monocoque

Shimano Ultegra R80020 11 speed groupset - 50/34 chainrings, 11/28 cassette

Shimano Ice Tech disc rotors, 140mm

Mason X Hunt 4season disc wheelset

Schwalbe G-One 30mm tyres

Threaded bottom bracket, 68mm BSA

Deda headset

Deda Zero2 stem

Deda RHM 02 handlebars

Fabric Scoop Shallow saddle

Fabric Knurl bar tape

Tell us what the bike is for

Mason says, "4Season Dominance: a premium, Italian crafted, custom tubed, Dedacciai Aluminium framed bike with many of the advanced features of modern carbon bikes, but offering way more. Thru-Axle front and rear with the latest 'Flat-Mount Disc' brakes, adaptable internal routing, Electronic shifting and 1x gearing options and clearance for larger tyres and mudguards mean our bikes are perfect for getting your head down and knocking off the miles in all seasons and across all surfaces."

The Definition "focuses on a niche that we (Mason) believe is under-developed and give it our full attention to produce the absolute best product possible."

The bikes are designed to take full advantage of the exciting new developments in braking and shifting technology and are built using what we consider to be the ideal component mix at each level.

Built up to a performance standard, not down to a price point, the Definition bikes are designed to last a long time and the modern features mean they won't date fast and can be updated as your needs and riding style changes.

These bikes are designed to go a long way in comfort, the geometry is designed for stability at speed and when loaded and the slacker, but not too slack, angles work perfectly with disc brakes and perform dependably on a variety of surfaces, on and off road. Longer head tubes mean you are not too head-down for comfort, but they are a sensible length to ensure that power isn't compromised when accelerating and climbing.

"Above all, we worked to ensure the Definition has an engaging and spirited ride that makes you want to come back to the bike and take it far and fast. That really is the essence of this premium aluminium model."

Frame and fork

Overall rating for frame and fork

Tell us about the build quality and finish of the frame and fork?

It's a thing of beauty – the fork flares out to accommodate the discs but from the side it looks clean and seamless. The frame matches and surpasses some carbon frames I've ridden, and together everything just works. The branding is nice and clean, and I like that it's slightly busier-looking on the fork.

The paint job and general aesthetics of the frame and fork are top class in my opinion.

Tell us about the materials used in the frame and fork?

Aluminium frame and full-carbon fork.

Tell us about the geometry of the frame and fork?

The top tube is quite long (55.1cm on a 54cm frame) and the frame has a fairly slack head angles – 71.5 degrees. It's on the sharper side of endurance bike, but not quite race geometry.

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

The chainstays and effective top tube are quite long, yet the seat tube angle is the same as that of a race bike. The reach is quite long so you can achieve a pretty racy position down on the drops if required.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

Very comfortable and accurate, with fantastic handling.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

It's very well balanced, among the best I've ridden, carbon or alloy, in terms of a pleasant all-round ride feel. The bottom bracket area is quality and stable, no creaks or fragility whatsoever.

How did the bike transfer power? Did it feel efficient?

Very efficient indeed; with 30mm tyres I'm faster on this bike than on my rim-brake-equipped winter hack that has 25mm tyres on a rough cycle path commute.

Was there any toe-clip overlap with the front wheel? If so

A little bit from almost standing starts at traffic lights and bridge crossings.

How would you describe the steering? Was it lively One of the best features for me was the acceleration out of corners – it makes you want to go fast, it's extremely nippy even though it's not light.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

I'm convinced my handling is better on this bike! You don't get any of the harshness sometimes associated with aluminium frames.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

The saddle won't be to everyone's liking; it's very flat, so those who like a groove or more padding might want to swap it out for something more padded. I've heard some rumblings about the smaller rotors specced on the Hunt wheels, but for me they offer phenomenal stopping power on the road. You can change for 160mm if required anyway.

Deda's 02 bars are perfectly comfortable, and combined with Shimano's new brake lever hoods they feel really nice in your hands.

Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?

Undoubtedly the frame combined with the specially designed carbon fork. It feels as stiff as many all-carbon bikes I've ridden. For '4Season' purposes I think the wheelset provided is perfect.

Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?

The new Shimano Ultegra groupset goes perfectly with the responsiveness of the bike – quick and crisp gear changes. The Definition deserves at least an Ultegra-level groupset, and it's what I'd choose if I was buying one.

Rate the bike for efficiency of power transfer:

It's easily comparable to a carbon frame in terms of power transfer, you really feel that none of your effort is wasted.

Rate the bike for acceleration:

This is a highlight of the bike, and one I wasn't expecting. Acceleration is great, it makes you want to go fast.

Rate the bike for sprinting:

It feels much faster than the weight and geometry would suggest – and accelerates very well.

Rate the bike for high speed stability:
Rate the bike for cruising speed stability:
Rate the bike for low speed stability:
Rate the bike for flat cornering:

It's impressively accurate.

Rate the bike for cornering on descents:

Accurate and solid, no problems here.

Rate the bike for climbing:

More upright geometry makes climbing easier, and compact gearing supplied will be welcome for hilly rides.

The drivetrain

Rate the drivetrain for performance:

All working perfectly after many miles, and the shifting is crisp and clean.

Rate the drivetrain for durability:

No adjustments needed yet after well over 1,000 miles.

Rate the drivetrain for weight:

Marginally heavier than Dura-Ace, for far less money.

Rate the drivetrain for value:

Very nearly as good as Dura-Ace, for far less money.

Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?

I'm a big fan of new mechanical Ultegra, and you can't argue with getting the full groupset included with no corners cut.

Wheels and tyres

Rate the wheels for performance:

They complement the bike really well, are great with the wider tyres and not too heavy.

Rate the wheels for durability:

Strong and still true after many miles on very rough roads.

Rate the wheels for weight:

Not the lightest (this is an area you could save weight if you wanted to) but they work on this bike.

Rate the wheels for comfort:
Rate the wheels for value:

Tell us some more about the wheels.Did they work well in the conditions you encountered? Would you change the wheels? If so

They're perfect for the all-season job for which they are intended, which I guess is the reason Mason put its name on them.

Rate the tyres for performance:

I love these tyres, and wish my other bikes could take them in 30mm.

Rate the tyres for durability:

Still look basically new and no punctures or nicks, even though I've tried my very best to destroy them.

Rate the tyres for weight:
Rate the tyres for comfort:

About as comfortable as you can get on a road bike, with not a great deal of speed sacrifice.

Rate the tyres for value:

Competitively priced and long-lasting, no complaints.

Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so

I'd change them out for 25 or 28mm race tyres if I wanted to race the Definition (something I believe it would be perfectly capable of) but for winter riding and training they're perfect and will last you the year with ease.


Rate the controls for performance:
Rate the controls for durability:
Rate the controls for weight:
Rate the controls for comfort:

Your summary

Did you enjoy riding the bike? Yes

Would you consider buying the bike? Yes

Would you recommend the bike to a friend? Yes

Rate the bike overall for performance:
Rate the bike overall for value:

Use this box to explain your overall score

A fantastic bike is now (marginally) even better – to look at the Definition2 at face value the liveliness of the ride almost defies logic, yet it's super-comfortable and I was happy riding this all day, every day. If I had to have one multi-purpose bike, this would without doubt be it.

Overall rating: 9/10

About the tester

Age: 27  Height: 179cm  Weight: 75kg

I usually ride: Road bike (currently Specialized Tarmac)  My best bike is: Ridley Chronus TT bike

I've been riding for: Under 5 years  I ride: Every day  I would class myself as: Experienced

I regularly do the following types of riding: road racing, time trialling, commuting, club rides, sportives, general fitness riding, triathlon races

Arriving at in 2017 via 220 Triathlon Magazine, Jack dipped his toe in most jobs on the site and over at eBikeTips before being named the new editor of in 2020, much to his surprise. His cycling life began during his students days, when he cobbled together a few hundred quid off the back of a hard winter selling hats (long story) and bought his first road bike - a Trek 1.1 that was quickly relegated to winter steed, before it was sadly pinched a few years later. Creatively replacing it with a Trek 1.2, Jack mostly rides this bike around local cycle paths nowadays, but when he wants to get the racer out and be competitive his preferred events are time trials, sportives, triathlons and pogo sticking - the latter being another long story.  

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sergius replied to Bassmann13 | 6 years ago
Bassmann13 wrote:
Prosper0 wrote:

Ten. Kilos. Aluminium. Ultegra. Three. thousand. pounds. 

Chaps, come on. 


Equivalent pricing to a Spesh Roubaix Comp, better spec than a Trek Checkpoint SL5 etc etc.  Weight isn't everything, and I'd take the Mason all day long over the big brands if (when) I have the chance.


It's noticeable though. 


My 10kg Canyon Inflite vs my 7kg Rose. 

Alu vs Carbon.

Both Ultegra w/ discs.


I really don't like heavy Aluminium frames nowadays.  Lighter bikes feel faster and more responsive for me. 

Jack Sexty replied to Prosper0 | 6 years ago

Prosper0 wrote:

Ten. Kilos. Aluminium. Ultegra. Three. thousand. pounds. 

Chaps, come on. 

As weight appears to be a talking point here, I've actually just got a note from Mason who insist they weighed the same bike at a fraction under 9kg - I would be surprised if our scales were that far off, but it's 100% closer to 9 than 10kg. In the meantime, we're going to check the calibration of our scales...

Dom replied to Prosper0 | 6 years ago
1 like
Prosper0 wrote:

Ten. Kilos. Aluminium. Ultegra. Three. thousand. pounds. 

Chaps, come on. 

Hi Prosper0,

Please see my response above.


Dom | Mason Cycles.


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