Indicative frame size
Multiply inseam by 0.59 to estimate frame size in centimetres, then divide by 2.54 for inches. An 82 cm inseam gives about 48 cm or 19 inches.
Important: 29-inch wheels do not mean a 29-inch frame. Wheel diameter and frame size are different measurements.
Letters and inches vary
| Information | Meaning | Use |
|---|---|---|
| S–XL | Brand range | First filter only |
| 15–21″ | Approximate frame size | Older comparison |
| 27.5 / 29″ | Wheel format | Handling and rollover |
Three essential checks
Reach
Reach strongly affects the standing attack position. Too short can feel cramped; too long can make weighting the front wheel difficult.
Standover and dropper insertion
Keep room to move over the bike and check that the dropper post can be inserted low enough for your saddle height.
Wheelbase and intended use
Cross-country bikes favour efficiency; trail and enduro models often use longer, slacker geometry for stability.
Between two sizes
A smaller bike is usually easier to move beneath the rider. A larger bike can feel calmer at speed but requires enough reach and control. Do not compensate for a clearly wrong frame solely with stem length.
Checklist
- Compare reach, stack and wheelbase.
- Check standover and dropper insertion.
- Use the chart for the exact wheel size and model year.
- Consider technical terrain and riding speed.
- Test both standing and seated positions.