Road endurance
Mason Definition 3
2025 · 700c wheels · 8 sizes
Third generation of Mason's Dedacciai aluminium all-road frame, a sporty, all-season road bike with full mudguard clearance and room for 35 mm tyres (32 mm with mudguards). Mason publishes one geometry table covering both the Definition and its steel sibling, the Resolution. Trail figures are Mason's own; Mason does not say which tyre size they assume. Mason's table prints the 48 cm centre-to-centre seat tube as 43.29; it should read 432.9. Stem, bar and crank sizes are from the Definition 3 Shimano build; where Mason lists two options for a size, that size is left blank.
Source: masoncycles.cc/products/definition-frameset-definition-frameset
Size run
Published geometry by size. How each size rides and fits for your rider profile loads with the page.
| Size | 48 | 50 | 52 | 54 | 56 | 58 | 60 | 62 |
|---|---|---|---|---|---|---|---|---|
| Stack (mm) | 532 | 543 | 553 | 566 | 580 | 591 | 599 | 620 |
| Reach (mm) | 370 | 381 | 383 | 383 | 388 | 395 | 397 | 406 |
| Head angle (°) | 71.0 | 71.5 | 71.5 | 71.5 | 71.5 | 72.0 | 72.0 | 72.5 |
| Seat angle (°) | 74.5 | 74.5 | 74.5 | 73.5 | 73.5 | 72.5 | 72.5 | 72.5 |