Bike Size Guide
Not sure what size to go for? Use this guide to find your fit. As a general rule, it's safer to size down than up — especially with secondhand bikes, where you can't fully customise the setup like you can with new.
A quick note on secondhand bikes: because every bike we sell is preloved, sizing can vary slightly between brands and models even at the same "frame size." The charts below are a great starting point, but if you're between sizes or unsure, message us with your height and inside leg measurement before you buy — we're happy to check a specific bike's geometry against your measurements.
How to measure yourself
Height: Stand against a wall in socks (no shoes) and measure straight up from the floor.
Inseam (inside leg): This is the measurement that matters most for bike fit — it's different from your trouser inseam.
- Take off your shoes and stand with your back against a wall.
- Place a book between your legs, spine up, and pull it up firmly into your crotch as if it were a saddle.
- Keep the book level and pressed against the wall.
- Measure from the top edge of the book straight down to the floor.
That measurement is your inseam for bike sizing purposes.
Mountain Bikes
MTB sizes are usually given in inches or as XS–2XL. As a rough guide, smaller frames tend to run 27.5" wheels and larger frames 29" wheels — check the individual listing for wheel size.
| Height | Inseam | Size |
|---|---|---|
| 4'9" – 5'1" (145–155cm) | 69–73cm | XS |
| 5'1" – 5'5" (155–165cm) | 74–78cm | S |
| 5'5" – 5'9" (165–176cm) | 79–83cm | M |
| 5'8" – 5'11" (173–180cm) | 81–86cm | M/L |
| 5'10" – 6'2" (177–188cm) | 84–89cm | L |
| 6'2" – 6'5" (188–195cm) | 89–91cm | XL |
| 6'5" – 6'8" (195–203cm) | 91–97cm | 2XL |
Road, Gravel & Cyclocross Bikes
Road bike sizes are usually given in centimetres (frame/seat tube size).
| Height | Inseam | Frame size |
|---|---|---|
| 5'0" – 5'2" (152–158cm) | 71–75cm | 48cm |
| 5'2" – 5'4" (158–163cm) | 74–77cm | 50cm |
| 5'4" – 5'6" (163–168cm) | 76–79cm | 52cm |
| 5'6" – 5'9" (168–174cm) | 78–82cm | 54cm |
| 5'9" – 5'11" (174–180cm) | 81–85cm | 56cm |
| 5'11" – 6'1" (180–185cm) | 84–87cm | 58cm |
| 6'1" – 6'3" (185–190cm) | 86–90cm | 60cm |
| 6'3" – 6'5" (190–195cm) | 89–92cm | 62cm |
Hybrid, Commuter & City Bikes
Hybrids are usually sized XS–XL rather than in cm.
| Height | Inseam | Size |
|---|---|---|
| 4'10" – 5'1" (147–155cm) | 69–73cm | XS |
| 5'1" – 5'5" (155–165cm) | 72–78cm | S |
| 5'5" – 5'9" (165–175cm) | 77–83cm | M |
| 5'9" – 6'1" (175–186cm) | 82–88cm | L |
| 6'1" – 6'6" (186–197cm) | 87–93cm | XL |
Still not sure?
Send us your height and inside leg measurement (and the bike you're looking at) and we'll help you get it right before you buy.
Sizing is a guide only. Actual fit varies by brand, model and geometry — check the specific listing where available.