Models · Mason · Definition
Mason Definition 3 (2026)
Good to know: Conventional cockpit, sized to the frame · Configurable build
Conventional cockpit, sized to the frame. Mason fits a conventional Deda stem and bars (ZERO100 or ZERO2). Bar width and stem length go up with frame size, and you can change the stem length when you order. The website doesn’t say which length comes on which size.
Configurable build (at least partly: the cockpit or bar width, for example). The stock build below is only one of the options.
Geometry ?
Mason Definition 3 2026 geometry in sizes 48CM–62CM: stack 532.1–620.1 mm, reach 369.7–405.5 mm, head angle 71–72.5°.
| 48CM | 50CM | 52CM | 54CM | 56CM | 58CM | 60CM | 62CM | |
|---|---|---|---|---|---|---|---|---|
| Stack | 532.1 mm | 543.3 mm | 552.8 mm | 565.5 mm | 579.7 mm | 591.1 mm | 599.1 mm | 620.1 mm |
| Reach | 369.7 mm | 380.6 mm | 382.5 mm | 383 mm | 388.3 mm | 394.7 mm | 396.8 mm | 405.5 mm |
| Head angle | 71° | 71.5° | 71.5° | 71.5° | 71.5° | 72° | 72° | 72.5° |
| Seat angle | 74.5° | 74.5° | 74.5° | 73.5° | 73.5° | 72.5° | 72.5° | 72.5° |
| Seat tube (c-t) | 480 mm | 500 mm | 520 mm | 540 mm | 560 mm | 580 mm | 600 mm | 620 mm |
| Head tube | 120 mm | 130 mm | 140 mm | 155 mm | 170 mm | 180 mm | 190 mm | 210 mm |
| Top tube (effective) | 519 mm | 532.8 mm | 537.4 mm | 551.5 mm | 561.1 mm | 581.3 mm | 586 mm | 601 mm |
| BB drop | 73 mm | 73 mm | 73 mm | 71.5 mm | 71.5 mm | 71.5 mm | 70 mm | 70 mm |
| Chainstay | 420 mm | 420 mm | 420 mm | 420 mm | 420 mm | 420 mm | 420 mm | 420 mm |
| Wheelbase | 989 mm | 999.1 mm | 1004.1 mm | 1009.6 mm | 1019.7 mm | 1024.7 mm | 1030.2 mm | 1040.2 mm |
| Standover | 741.4 mm | 756.5 mm | 770.8 mm | 787.3 mm | 804 mm | 818.1 mm | 833.1 mm | 853.2 mm |
| Fork length | 380 mm | 380 mm | 380 mm | 380 mm | 380 mm | 380 mm | 380 mm | 380 mm |
| Fork offset | 45 mm | 45 mm | 45 mm | 45 mm | 45 mm | 45 mm | 45 mm | 45 mm |
| Stock build by size | ||||||||
| Cranks | 165 mm | 170 mm | 170 mm | 172.5 mm | 172.5 mm | 175 mm | 175 mm | 175 mm |
| Stem | 70 mm | – | 90 mm | 100 mm | 110 mm | 110 mm | 120 mm | 120 mm |
| Bar width | – | – | 420 mm | 440 mm | 440 mm | 460 mm | 460 mm | 460 mm |
Source: masoncycles.cc, checked 1 Nov 2026 · bar position: worked out from published data
An older model year in the archive with the same stack, reach and head angle: 2018. Source: masoncycles.cc
Stock build
Definition 3 Shimano (configurable, from) ≈ €3,364
- Groupset
- Shimano
- Stem
- Deda Zero100 or Zero2, various lengths
- Handlebar
- Choice of Deda options
- Seatpost
- MASON Penta carbon, microadjust
- Saddle
- Choice of Fizik options
- List price
- £2,900 (masoncycles.cc, 1 Nov 2026)
Options when ordering (manufacturer’s default in bold):
| Size | Cockpit |
|---|---|
| all | bars Deda Zero100 bars Deda Zero2 |
Source: masoncycles.cc, checked 1 Nov 2026
Frames with similar geometry
Stack and reach within 12 mm of size 48CM (stack 532.1 / reach 369.7 mm).
Stack and reach within 12 mm of size 50CM (stack 543.3 / reach 380.6 mm).
Stack and reach within 12 mm of size 52CM (stack 552.8 / reach 382.5 mm).
Stack and reach within 12 mm of size 54CM (stack 565.5 / reach 383 mm).
Stack and reach within 12 mm of size 56CM (stack 579.7 / reach 388.3 mm).
Stack and reach within 12 mm of size 58CM (stack 591.1 / reach 394.7 mm).
Stack and reach within 12 mm of size 60CM (stack 599.1 / reach 396.8 mm).
Stack and reach within 12 mm of size 62CM (stack 620.1 / reach 405.5 mm).
Spotted a mistake or a missing build? Let me know.
Are you the manufacturer, or do you sell this bike? I’m missing 3 values for this model’s stem and bars. Add them