	XXS	XS	S	M	L	XL
Stack	587mm	590mm	606mm	635mm	651mm	672mm
Reach	355mm	371mm	376mm	382mm	386mm	398mm
Stack to Reach Ratio	1.65:1	1.59:1	1.61:1	1.66:1	1.69:1	1.69:1
Seat Tube Length, Effective Center	360mm	395mm	440mm	470mm	510mm	530mm
Top Tube Length, Effective/Horizontal HT Top	529mm	549mm	559mm	573mm	581mm	599mm
Head Tube Angle	69.5deg	70deg	70deg	71deg	71deg	71deg
Seat Tube Angle	73.5deg	73.5deg	73.5deg	73.5deg	73.5deg	73.5deg
Head Tube Length	111mm	125mm	143mm	169mm	186mm	208mm
Bottom Bracket Drop	70mm	70mm	70mm	70mm	70mm	70mm
Bottom Bracket Height	273mm	273mm	273mm	273mm	273mm	273mm
Chainstay Length	440mm	440mm	440mm	440mm	440mm	440mm
Chainstay Length Horizontal	434.4mm	434.4mm	434.4mm	434.4mm	434.4mm	434.4mm
Front-Center	602mm	618mm	629mm	634mm	644mm	663mm
Front-Center Horizontal	598.6mm	614.6mm	625.6mm	630.6mm	639.6mm	658.6mm
Wheelbase	1033mm	1049mm	1060mm	1065mm	1074mm	1093mm
Fork Offset/Rake	51mm	51mm	51mm	51mm	51mm	51mm
Fork Length, Unknown	395mm	395mm	395mm	395mm	395mm	395mm
Trail	73.8mm high	70.6mm high	70.6mm high	64.2mm mid/neutral	64.2mm mid/neutral	64.2mm mid/neutral
Mechanical Trail	69.1mm	66.3mm	66.3mm	60.7mm	60.7mm	60.7mm
Wheel Flop	24.2mm	22.7mm	22.7mm	19.8mm	19.8mm	19.8mm
Standover Height	700mm	722mm	750mm	778mm	810mm	831mm
Tire to Pedal Spindle	94mm 165 mm cranks	110mm 165 mm cranks	116mm 170 mm cranks	118.5mm 172.5 mm cranks	128.5mm 172.5 mm cranks	145mm 175 mm cranks
Pedal Spindle to Ground Clearance	108mm 165 mm cranks	108mm 165 mm cranks	103mm 170 mm cranks	100.5mm 172.5 mm cranks	100.5mm 172.5 mm cranks	98mm 175 mm cranks

	XXS	XS	S	M	L	XL
Wheel Size	700C/29 in 622 mm BSD	700C/29 in 622 mm BSD	700C/29 in 622 mm BSD	700C/29 in 622 mm BSD	700C/29 in 622 mm BSD	700C/29 in 622 mm BSD
Tire Width	32mm	32mm	32mm	32mm	32mm	32mm
Tire Outer Diameter	686mm	686mm	686mm	686mm	686mm	686mm
Bike Length with Tires	1719mm	1735mm	1746mm	1751mm	1760mm	1779mm
Crank Length	165mm	165mm	170mm	172.5mm	172.5mm	175mm
Handlebar Width	580mm	580mm	600mm	600mm	620mm	620mm
Stem Length	60mm	70mm	70mm	80mm	90mm	100mm

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.

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2026 Specialized Bicycles Sirrus 4.0

Geometry