Definition 105 Di2 £3,595.00

InBoard Disc-Mount

The calliper is mounted on the chain stay, this allows us to use lighter more comfortable seat-stays and gives a flex free mounting for the post-mount components to be welded to. Mounting the brake on the chain stay also keeps it cleanly out of the way of rack and ‘guard stays.

EN Tested

All our frames and forks complete the brutal strength and fatigue testing to comply fully with EN regulations. They are pushed, pulled, dropped and twisted over 100,000 times and must survive without any damage before they can pass.

It's not law that frames and forks have to be tested to their limits like this, but our frames will always be tested in this way, so you can be sure that your MASON frame not only looks beautiful with a ride quality to match, but it is tough, safe and dependable too.

Multiport

Our frames use an adaptable, internal cable routing system. 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. We were the first to bring this type of system to a performance steel frame and now use this system across our range. Interchangeable alloy parts allow five options:

1. Full cable outer. 2. Hydraulic Hose. 3. Split outer. 4. Electronic cable [e.g. Shimano Di2]. 5. 2 x Hose/cable or Hose/Dynamo wire 6. Blank.

Taper Head Tubes

Our frames use modern 1-1/8” - 1.5” taper head tubes. Pioneered by composite frames, the taper head tube makes huge sense for metal frames too;

The large overall diameter provides a useful weld area. The fully integrated headset is light and has a very low stack-height. Large 1.5” lower bearing, mated to a tapered carbon fork steerer, spreads the load and gives flex-free braking and instant response to steering input.

Threaded Bottom Brackets

We choose a more traditional 68mm BSA, and T47 threaded standard for our frames because we know that it gives greater durability and creak-free reliability over many miles. The threaded BB is easier to service using standard tools and you are more likely to find a replacement when adventuring far from home. A properly lubricated, threaded BB is also an ideal interface with a metal BB shell.

BoatTail Stays

Unique to MASON. The seat stays flow out of the ovalised top tube and then curve and taper down to meet the chain stays which curve up towards the axle. We call this ‘BoatTail’, a custom bend giving disc-rotor and calliper clearance, helping to avoid chain-slap on the rough stuff and allowing a little compliance to help smooth the ride.

Aperture2 Fork

Designed and tooled for by us and unique to MASON. This frame is fitted with our beautiful 'Aperture2' 365g, Ø12mm thru-axle/flat-mount, monocoque carbon fork.

Features: Mason F-Stop axle system including replaceable axle inserts, TrueTaper steerer, Internal Routing for Dynamo and brake-hose, Full mudguard clearance, space for 32mm tyres + 'guards [up to 35mm without 'guards, depending on rim/tyre spec] Custom layup UD carbon construction, discrete eyelets.

F-Stop Axle System

Aluminium Dedacciai Tubing

The entire tubeset was developed in conjunction with Italian, metal tubing gurus Dedacciai. The Definition is constructed from Triple Butted, Hand Selected, custom shaped, 7000 series, Dedacciai Alu tubes and tig welded by hand with beautiful Smooth weld beads. The welds require no after sanding or finishing, so there is no thinning and weakening of the tubes at crucial areas. The frame is fully heat treated, stress relieved and anti-corrosion treated after welding.

27.2 Seat Post

Our oversize seat tubes don't house oversize seat posts. The large diameter seat tube helps the 'core-stability' of the frame but large, stiff seat posts don't help rider comfort. A 27.2mm post helps to dial out road-buzz and the smoother ride means you stay fresher for longer.

Internal Routing

We route the hoses and cables internally where practical, keeping the 'adventure nature' of our bicycles firmly in mind. For smoother runs and a cleaner aesthetic, all control cables, hoses and electronic shift control wires now run through the down tube, via the special BB shell and out through the chainstays, guided by our Mason 'MultiPort' adaptable inserts. Interchangeable Internal routing keeps the control cabling away from road dirt and grime, helps avoid accidental damage, makes cleaning easy, de-clutters your bike and means you can adapt your bike easily to work with various shifting and braking methods. For adventure and endurance riding, internal routing also has the advantage that it is easy to strap frame packs to the frame tubes without being hindered by external cabling and hoses.

Integrated Headset

Integrated, 41.8ø upper, 51.8ø lower, for taper head tube. Both bearings are ‘ACB’, meaning ‘Angular Contact Bearings’. The head-tube seat angle is 45º.

The headset drops into a tapered seat in the head tube and is tensioned using a headset tensioner within the fork steerer. Tensioning the headset centres it on the taper and prevents any play. The larger lower bearing allows a tapered steerer and larger crown. This gives sharper response, helps reduce flex under braking and spreads bearing load.

FlatMount Brake Calipers

Flat mount disc-brake callipers are lighter, neater, and open up more space within the dropout area for racks and ‘guards. The calliper is mounted to the dropout, allowing us to use a lighter, more comfortable seat-stay.  Up front, the calliper is mounted directly to the fork [via the brake manufacturers adaptor] and offers a cleaner and more minimalist appearance and also provides a compact packaging of the brake caliper.

D-Form Downtube

The DForm down tube is designed by us and tooled exclusively for MASON by Dedacciai in Italy. It is not a simple ‘D’ section and varies in shape from being taller/narrower at the head tube to being wider and lower in section where it meets the BB shell. This shape allows a very wide weld where the tube meets the BB, giving it great stability and ensuring that the weld doesn’t excessively overlap onto the base of the seat tube.

Thru-BB

'Thru-BB' is unique to MASON aluminium frames. The large 56mmØ presents a large weld area to the base of the down tube and then steps down to the 68mm [road/gravel] & 73mm [MTB] width threaded seats. This step-down provides plenty of space around the outside of the bottom-bracket bearings to allow the control cables and hose to pass through on the way to the chain stays/seat tube and out to the brake, rear mech, dropper-post etc.

IMPORTANT: This BB shell design requires the use of a bottom bracket with a 24mm or 30mm 'sleeved' axle like most Shimano or SRAM DUB, because the hose/cables/control wires run through the shell and under the axle. DO NOT use a bottom bracket type without a sleeve. Campagnolo sleeves are available on the site HERE. Please contact us if you would like advice on compatible cranksets/BB types.