2026 Principia Gravel 40 Base

	48cm	51cm	54cm	56cm	59cm
Stack	533.6mm	556.3mm	579mm	598mm	619mm
Reach	373mm	377.5mm	389mm	398.5mm	407mm
Stack to Reach Ratio	1.43:1	1.47:1	1.49:1	1.5:1	1.52:1
Seat Tube Length, Unknown	480mm	510mm	540mm	560mm	590mm
Top Tube Length, Effective/Horizontal Center	526mm	537mm	555mm	570mm	584.5mm
Top Tube Slope	8.1deg	7.3deg	6.4deg	6.2deg	5.2deg
Head Tube Angle	69.5deg	70.5deg	71.5deg	71.2deg	72deg
Seat Tube Angle	74deg	74deg	74deg	74deg	74deg
Head Tube Length	115mm	135mm	155mm	175mm	195mm
Bottom Bracket Drop	67mm	67mm	67mm	67mm	67mm
Bottom Bracket Height	289mm	289mm	289mm	289mm	289mm
Chainstay Length	435mm	435mm	435mm	435mm	435mm
Chainstay Length Horizontal	429.8mm	429.8mm	429.8mm	429.8mm	429.8mm
Front-Center	599.3mm	602.2mm	611.4mm	627.2mm	637.2mm
Front-Center Horizontal	595.5mm	598.5mm	607.8mm	623.7mm	633.7mm
Wheelbase	1025.3mm	1028.3mm	1037.6mm	1053.5mm	1063.5mm
Fork Offset/Rake	45mm	45mm	45mm	45mm	45mm
Fork Length, Unknown	400mm	400mm	400mm	400mm	400mm
Trail	85.1mm very high	78.3mm high	71.7mm high	73.7mm high	68.4mm high
Mechanical Trail	79.7mm	73.8mm	68mm	69.7mm	65mm
Wheel Flop	27.9mm	24.7mm	21.6mm	22.5mm	20.1mm
Tire to Pedal Spindle	73.3mm 170 mm cranks	76.2mm 170 mm cranks	85.4mm 170 mm cranks	101.2mm 170 mm cranks	111.2mm 170 mm cranks
Pedal Spindle to Ground Clearance	119mm 170 mm cranks	119mm 170 mm cranks	119mm 170 mm cranks	119mm 170 mm cranks	119mm 170 mm cranks

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://principiabikes.com/gravel/gravel-aluminium/gravel-40---bronze-pg-2588

Geometry