Mason Definition
Mason Definition
Mason Definition
Mason Definition
Mason Definition
Mason Definition
Mason Definition

Mason Definition

$1,495.00 USD


Our Definition frame set uses lightweight, Premium Dedacciai aluminium tubing to provide a responsive and engaging ride. Take it far and fast.


Full details and photographs on website soon

MultiPort internal cable routing, disc brake specific, suitable for larger tyres mudguards and rack. Choose the Alu. Definition if you love to ride all day, in all seasons, attacking climbs and descents along the way. Why Aluminium? Read more here.

The Dedacciai aluminium frame is a super efficient pedalling and power transmission machine. Low weight, straighter stays and large diameter down tube give it a punchy and responsive ride. It has more of a race-bike feel, although it still retains a beautiful ride quality because of the advanced tubing, custom BoatTail stays, advanced taper steerer Aperture carbon fork and of course the capacity for larger tyres.

Teamed with the fingertip control of a modern disc brake system, this frameset is the basis for a hugely entertaining, practical and addictive bike.

We use our own MultiPort adaptable, internal cable routing system for this frame. Developed by us to allow your Mason frame to be used with a combination of control systems and adapt and evolve with your requirements and riding styles.

Interchangeable alloy parts allow five options: 1. Full cable outer. 2. Hydraulic Hose. 3. Split outer. 4. Electronic cable [e.g. Shimano Di2]. 5. Blank.

We worked very hard to make sure all cable routes are as smooth and direct as possible to minimise drag and increase life and efficiency, there are no 'sumps' in the cable runs to prevent moisture collection and shift deterioration.

  • As with all our frames, the tubes are hand picked and custom formed where necessary to ensure the bike performs in the way we envisage. We don’t simply order an ‘off the shelf’ tube set.
  • Like the top tube on it’s steel cousin, the top tube used for the Definition has a pronounced oval section. The wide profile gives great lateral stability and gives a large weld area at the head tube, increasing strength and durability. The tube flows beautifully into the seat stays as it passes the seat tube, excellent structurally at this crucial area.
  • A full 48mmØ down tube allows wall thickness to be pared down without loss of overall strength, torsional stability and ride quality. The oversize tube also gives a greatly increased weld area at the base of the taper head tube and at the bottom-bracket shell, and allows us to pass the control cables, hose and wires cleanly through.
  • The modern taper head tube takes our own, taper-steerer 'Aperture' full carbon fork, providing flex-free braking and instant response to steering input. Read more about our fork here. An oversize seat tube gives the frame superb core-stability and keeps the BB stable, we use a 27.2mm post size for comfort.
  • Flowing out of the ovalised top tube then curving and tapering down to the axle, our custom seat stays with their clever ‘BoatTail’ tube design has a custom bend giving disc-rotor and calliper clearance and allow a little compliance to tune out road-buzz. The chain stays are deep section for efficient power transfer and are tapered and curved for ride-quality and to provide clearance for full ‘guards and larger tyres. Once again we add a custom bend so they work perfectly with the disc rotor and calliper.

Read more about the tubing here.

All eyelets are discretely hidden on the inside of stays where practical. This keeps things looking clean and business-like when the ‘guards are off. The rear eyelets are placed away from the dropouts inside the seat stays so there is no interference with the disc-calliper. Proper, separate eyelets for rack mean no 'doubling up' onto the mudguard mounts when fitting a rack.

Even the BB shell on this clever frame is a custom part, machined specially for us. The 50mmØ shell presents a huge weld area to the base of the down tube and then steps down to 68mm width threaded seats. This unique design provides plenty of space around the outside of the bottom-bracket bearings to pass control cables and hose through on the way to the chain stays and out to the brake and rear mech.

NOTE: This BB shell design requires the use of a bottom bracket with a 'sleeved' axle. P

As for the Resolution frame, a specially designed 3D printed, structural nylon cable stop guides the front mech cable smoothly around the BB.

A modern and highly refined aluminium frame, designed to cover the miles fast in all seasons and keep you engaged along the way.

The following parts are provided with your frameset;

Deda Headset. Expander-bung for fork. M∆SON Macro clamp. Marine Grade Stainless bolts x 12. M∆SON 3D printed Structural Nylon BB guide inc screws. M∆SON 3D printed Structural Nylon mudguard mounts for fork x 2. Cable liner for front mech. Di2 rubber grommet 45º x 3. Rubber blanking grommet x 1.

MultiPort Inserts: Hose/outer x 4. Interrupted-outer x 2. Di2 x 2. Blank x 2.


  50CM 52CM 54CM 56CM 58CM 60CM
SEAT TUBE C/T 500 520 540 560 580 600
SEAT TUBE C/C 452.7 473.0 493.5 513.6 534.1 554.0
BB DROP 73 73 71.5 71.5 71.5 70
REAR CENTRE 420 420 420 420 420 420
TT EFFECTIVE 532.8 537.4 551.5 561.1 581.3 586
TT ACTUAL 516.8 522.7 536.3 546.7 566.9 574.3
STACK 543.3 552.8 565.5 579.7 591.1 599.1
REACH 380.6 382.5 383.0 388.3 394.7 396.8
STAND-OVER 756.5 770.8 787.3 804 818.1 833.1
OFFSET 45 45 45 45 45 45
TRAIL 66.3 66.3 66.3 66.3 63.2 63.2
FORK CROWN HEIGHT 380 380 380 380 380 380
HEAD ANGLE 71.5º 71.5º 71.5º 71.5º 72º 72º
HEAD TUBE LENGTH 130 140 155 170 180 190
SEAT TUBE ANGLE 74.5º 74.5º 73.5º 73.5º 72.5º 72.5º
WHEELBASE 999.1 1004.1 1009.6 1019.7 1024.7 1030.2
FRONT CENTRE 590 595 600 610 615 620
AXLE SPACING 135 135 135 135 135 135
FORK WEIGHT APERTURE 365g 365g 365g 365g 365g 365g
STEM 90 90 100 110 110 120
CRANKARM 170 170 172.5 172.5 175 175