A road-like starting estimate
Multiply inseam by 0.66. An 84 cm inseam gives about 55 cm, which may be labelled M, 54, 55 or 56 depending on the brand.
Key point: select one or two candidate sizes, then compare their full geometry.
Match geometry to use
| Main use | Desired feel | Check |
|---|---|---|
| Road and smooth tracks | Dynamic | Reach, bar height |
| Long distance | Comfort and stability | Stack, luggage space |
| Technical trails | Control | Wheelbase, standover |
| Loaded touring | Predictability | Load distribution |
Essential geometry
Reach and cockpit
Flared bars, stem length and handlebar reach all change how far your hands sit from the saddle.
Stack and long-ride comfort
A higher stack can reduce the effort needed to hold a sustainable position for several hours.
Standover and tyres
Extra clearance is helpful on rough ground. Check tyre size, toe overlap and whether mudguards or bags reduce available space.
Between two sizes
The smaller option usually offers more clearance and a compact feel. The larger option may create a longer, calmer cockpit. Consider torso and arm length, mobility and the components supplied.
Checklist
- Measure inseam twice.
- Use the exact model-year geometry chart.
- Compare stack, reach and standover with a known bike.
- Include luggage and intended terrain.
- Test the riding position if possible.