Tools you might need next
Calculate bicycle gear ratios, gear inches, and development for any chainring and cassette cog combination on your bike.
Calculate bicycle spoke length from hub flange diameter, rim ERD, lacing pattern, and number of crosses for wheel building.
Calculate optimal bicycle tire pressure from rider weight, tire width, wheel diameter, and riding surface for comfort and grip.
Standover clearance is inseam minus frame standover height. Road bikes often leave 1 to 2 inches; MTB may need more.
frame size (cm) ≈ inseam (cm) × 0.65 for road (rule-of-thumb starting point)Aggressive road fit uses longer reach; comfort hybrids favor shorter top tubes relative to seat tube length.
Labels like 54 cm or size M map differently across brands. Use calculated size as a starting range, not a single answer.
Updated: July 2026
Cross-check inseam-based size against brand geometry charts before ordering.
Use height and inseam together when a rider is between kids and adult sizing.
Compare suggested sizes when the same rider wants slack MTB geometry vs. longer gravel reach.
Combine inseam, reach preference, and the brand's geometry table.
Off-road riding needs extra clearance when dismounting on uneven terrain.
Start with body measurements instead of guessing S/M/L. Enter height, inseam, and bike type to get suggested frame size in centimeters or inches.