Mountain bike size chart by height
Roots, rocks and grins. The right size makes the bike feel like it's on your side.
Mountain bikes are sized by letter (XS to XXL), and some trail bikes use style-based sizes instead (Specialized's S1 to S6). Height gets you a starting size; brands overlap their ranges, and reach decides between two sizes.[1 3 · Oct 22, 2026] Always check the chart for the exact model you are buying.
Quick lookup by rider height
| Rider height | Trek Marlin (Gen 3)[2 2nd-hand · Oct 22, 2026] | Specialized XC/hardtail (Epic, Chisel, Rockhopper)[4 2nd-hand · Oct 22, 2026] | Specialized S-Sizing (Stumpjumper, Levo)[3 4 2nd-hand · Oct 22, 2026] |
|---|---|---|---|
| 5'0" (152 cm) | XS | XS | S1 |
| 5'4" (163 cm) | S | S | S2 |
| 5'8" (173 cm) | M or ML | M | S2, S3 or S4 |
| 6'0" (183 cm) | L | L | S4 or S5 |
| 6'4" (193 cm) | XL | XL or XXL | S5 or S6 |
The lookup is our own restatement of the brand charts below (centimeters converted from feet and inches and rounded).
Trek Marlin size chart (rider height and inseam)
| Size | Rider height | Inseam |
|---|---|---|
| XS | 4'9"–5'1" (145–155 cm) | 27–29 in (69–73 cm) |
| S | 5'1"–5'5" (155–165 cm) | 29–31 in (74–78 cm) |
| M | 5'5"–5'10" (165–177 cm) | 31–33 in (79–83 cm) |
| ML | 5'8"–5'11" (173–180 cm) | 32–34 in (81–86 cm) |
| L | 5'10"–6'2" (177–188 cm) | 33–35 in (84–89 cm) |
| XL | 6'2"–6'5" (188–195 cm) | 35–36 in (89–91 cm) |
| XXL | 6'5"–6'8" (195–203 cm) | 36–38 in (91–97 cm) |
On the Marlin, XS and S use 27.5-inch wheels and the larger sizes use 29-inch wheels.[2 2nd-hand 5 · Oct 22, 2026]
Specialized size ranges
| XC/hardtail size | Rider height | S-Size | Rider height | |
|---|---|---|---|---|
| XS | 148–155 cm | S1 | 4'11"–5'3" | |
| S | 158–165 cm | S2 | 5'2"–5'8" | |
| M | 165–178 cm | S3 | 5'5"–5'11" | |
| L | 178–185 cm | S4 | 5'8"–6'2" | |
| XL | 185–193 cm | S5 | 5'10"–6'4" | |
| XXL | 191–200 cm | S6 | 6'2"–6'8" |
With S-Sizing, a lower number is more nimble (shorter reach) and a higher number is more stable at speed; Specialized's own example puts a 5'8" rider on S3 for balance, S2 for nimble or S4 for stability.[3 · Oct 22, 2026]
General mountain bike size chart (not brand-specific)
A widely shared shop chart, useful as a first guess before you open a brand chart:
| Size | Rider height | Traditional frame size |
|---|---|---|
| XS | 4'9"–5'1" | 13–14 in |
| S | 5'2"–5'5" | 15–16 in |
| M | 5'6"–5'10" | 17–18 in |
| L | 5'11"–6'1" | 19–20 in |
| XL | 6'2"–6'4" | 21–22 in |
| XXL | 6'4" and up | 23 in |
Heights are the chart's feet-and-inches figures.[6 · Oct 29, 2026] (Its centimeter figure for L, 170–185 cm, doesn't match its own 5'11"–6'1" range, so we use feet and inches.) The same guide calls 29-inch wheels ideal for riders over 5'7" and 27.5-inch wheels suitable for adults about 5'2" to 5'10", and notes some brands put 27.5-inch wheels on XS and S frames.[6 · Oct 29, 2026]
Between two sizes?
- Compare reach, not seat tube. Trek recommends comparing reach and effective top tube across sizes and brands; reach matters most when you ride standing on the pedals.[1 · Oct 22, 2026]
- Size down for a shorter, more playful bike or if your torso and arms are short for your height.[1 · Oct 22, 2026]
- Size up for more stability on fast descents or if your torso and arms are long for your height.[1 · Oct 22, 2026]
- Use inseam to break ties where height ranges overlap (for example Trek's M and ML).[2 2nd-hand · Oct 22, 2026]
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Road bikes are sized differently: see the road bike size chart.
Sources: 1. Trek, What size mountain bike do I need? 2. Trek's Marlin Gen 3 sizing table as published by Trek dealers: The Wheel House and Bicycle Barn (second-hand). 3. Specialized, S-Sizing. 4. Specialized size guides as published by UK dealer The Ark Cycles (second-hand). 5. Trek, Marlin 5 specifications (XS and S tire size 27.5 in). 6. Ridley's Cycle, Mountain bike size chart and fit guide (checked Oct 29, 2026). Checked Oct 22, 2026.