	S	M	L	XL
Stack	584mm	592mm	600mm	615mm
Reach	437mm	457mm	477mm	500mm
Stack to Reach Ratio	1.34:1	1.3:1	1.26:1	1.23:1
Seat Tube Length, C-T	420mm	430mm	460mm	490mm
Top Tube Length, Effective/Horizontal Center	574mm	597mm	621mm	649mm
Top Tube Slope	18.1deg	17.3deg	14.6deg	12.7deg
Head Tube Angle	66.75deg	66.75deg	66.75deg	66.75deg
Seat Tube Angle	75.6deg	75.6deg	75.6deg	75.6deg
Head Tube Length	84mm	93mm	101mm	118mm
Bottom Bracket Drop	53mm	53mm	53mm	53mm
Bottom Bracket Height	317.7mm	317.7mm	317.7mm	317.7mm
Chainstay Length	432mm	432mm	432mm	432mm
Chainstay Length Horizontal	428.7mm	428.7mm	428.7mm	428.7mm
Front-Center	714mm	738mm	762mm	791mm
Front-Center Horizontal	710.3mm	742.3mm	759.3mm	789.3mm
Wheelbase	1139mm	1171mm	1188mm	1218mm
Fork Offset/Rake	44mm	44mm	44mm	44mm
Fork Length (On-Axis)	513mm	513mm	513mm	513mm
Trail	111.4mm very high	111.4mm very high	111.4mm very high	111.4mm very high
Mechanical Trail	102.3mm	102.3mm	102.3mm	102.3mm
Wheel Flop	40.4mm	40.4mm	40.4mm	40.4mm
Standover Height	725mm	725mm	725mm	765mm
Tire to Pedal Spindle	173.3mm 170 mm cranks	197.3mm 170 mm cranks	221.3mm 170 mm cranks	250.3mm 170 mm cranks
Pedal Spindle to Ground Clearance	147.7mm 170 mm cranks	147.7mm 170 mm cranks	147.7mm 170 mm cranks	147.7mm 170 mm cranks

Published Sizing Recommendations

Height

14 ft 4 in

15 ft 0 in

15 ft 8 in

Very Upright

Somewhat Upright

Average

Somewhat Aggressive

Very Aggressive

The Bike Insights Upright/Aggressive scale is based on analysis of a bike’s proportions relative to similar sized bikes in the same category.

Category Trend

Source:https://bmc-switzerland.com/collections/cross-country-mtb-bikes/products/fourstroke-01-three-bikes-bmc-26a-000049#custom_specs_N4gpKw

2026 BMC Switzerland Fourstroke 01 THREE Base