	XS	XS	S	S	M	M	L	L	XL	XL	XXL
Stack	515mm	515mm	537mm	537mm	555mm	555mm	578mm	578mm	603mm	603mm	628mm
Reach	360mm	360mm	370mm	370mm	380mm	380mm	390mm	390mm	400mm	400mm	410mm
Stack to Reach Ratio	1.43:1	1.43:1	1.45:1	1.45:1	1.46:1	1.46:1	1.48:1	1.48:1	1.51:1	1.51:1	1.53:1
Seat Tube Length, C-T	470mm	470mm	490mm	490mm	510mm	510mm	530mm	530mm	550mm	550mm	570mm
Top Tube Length, Effective/Horizontal Center	510mm	510mm	526mm	526mm	546mm	546mm	562mm	562mm	584mm	584mm	602mm
Top Tube Slope	7.4deg	7.4deg	7.4deg	7.4deg	7.2deg	7.2deg	7.4deg	7.4deg	7.8deg	7.8deg	8.2deg
Head Tube Angle	70.8deg	70.8deg	71deg	71deg	71.2deg	71.2deg	72.6deg	72.6deg	72.8deg	72.8deg	72.8deg
Seat Tube Angle	74deg	74deg	74deg	74deg	73.5deg	73.5deg	73.5deg	73.5deg	73deg	73deg	73deg
Head Tube Length	93.2mm	93.2mm	115.7mm	115.7mm	134mm	134mm	150mm	150mm	175.5mm	175.5mm	201.6mm
Bottom Bracket Drop	78mm	78mm	78mm	78mm	78mm	78mm	78mm	78mm	78mm	78mm	78mm
Bottom Bracket Height	273mm	273mm	273mm	273mm	273mm	273mm	273mm	273mm	273mm	273mm	273mm
Chainstay Length	418mm	418mm	418mm	418mm	420mm	420mm	410mm	420mm	422mm	422mm	422mm
Chainstay Length Horizontal	410.7mm	410.7mm	410.7mm	410.7mm	412.7mm	412.7mm	402.5mm	412.7mm	414.7mm	414.7mm	414.7mm
Front-Center	577mm	577mm	592mm	592mm	607mm	607mm	602mm	602mm	618mm	618mm	635mm
Front-Center Horizontal	571.3mm	571.3mm	587.3mm	587.3mm	601.3mm	601.3mm	607.5mm	597.3mm	612.3mm	612.3mm	630.3mm
Wheelbase	982mm	982mm	998mm	998mm	1014mm	1014mm	1010mm	1010mm	1027mm	1027mm	1045mm
Fork Offset/Rake	56mm	56mm	56mm	56mm	56mm	56mm	48mm	48mm	48mm	48mm	48mm
Fork Length (Axle-To-Crown)	388mm	388mm	388mm	388mm	388mm	388mm	388mm	388mm	388mm	388mm	388mm
Trail	62.9mm mid/neutral	62.9mm mid/neutral	61.6mm mid/neutral	61.6mm mid/neutral	60.3mm mid/neutral	60.3mm mid/neutral	59.7mm mid/neutral	59.7mm mid/neutral	58.4mm mid/neutral	58.4mm mid/neutral	58.4mm mid/neutral
Mechanical Trail	59.4mm	59.4mm	58.3mm	58.3mm	57.1mm	57.1mm	57mm	57mm	55.8mm	55.8mm	55.8mm
Wheel Flop	19.6mm	19.6mm	19mm	19mm	18.4mm	18.4mm	17mm	17mm	16.5mm	16.5mm	16.5mm
Standover Height	743mm	743mm	763.2mm	763.2mm	782.2mm	782.2mm	803mm	803mm	824.8mm	824.8mm	846.4mm
Tire to Pedal Spindle	56mm 170 mm cranks	56mm 170 mm cranks	71mm 170 mm cranks	71mm 170 mm cranks	86mm 170 mm cranks	86mm 170 mm cranks	81mm 170 mm cranks	81mm 170 mm cranks	97mm 170 mm cranks	97mm 170 mm cranks	114mm 170 mm cranks
Pedal Spindle to Ground Clearance	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks	103mm 170 mm cranks

	XS	XS	S	S	M	M	L	L	XL	XL	XXL
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	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	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm
Tire Width Max	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm	40mm
Tire Outer Diameter	702mm	702mm	702mm	702mm	702mm	702mm	702mm	702mm	702mm	702mm	702mm
Bike Length with Tires	1684mm	1684mm	1700mm	1700mm	1716mm	1716mm	1712mm	1712mm	1729mm	1729mm	1747mm

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.

Learn more about the Upright/Aggressive Scale

Category Trend

Performance Road

Source:https://fiftyonebikes.com/wp-content/uploads/2024/04/FiftyOne-Sika-Geo-Bar-Stem-Table-.pdf, https://storage.fiftyonebikes.com/landing/FiftyOne-Sika-Geo-Bar-Stem-Table-1-1.png

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2025 FiftyOne Sika Base

Geometry

Base Build

Stack and Reach vs. Category Trend