2022 Bird Bikes Forge 140mm Fork

	Medium	Medium Long	Large	Extra Large
Stack	654mm	663mm	672mm	681mm
Reach	449mm	473mm	496mm	518mm
Stack to Reach Ratio	1.46:1	1.4:1	1.35:1	1.31:1
Seat Tube Length, C-T	395mm	420mm	445mm	470mm
Top Tube Length, Effective/Horizontal HT Top	605mm	630mm	655mm	680mm
Head Tube Angle	65.8deg	65.8deg	65.8deg	65.8deg
Effective Seat Tube Angle, ETT HT Top	76.8deg	76.8deg	76.8deg	76.8deg
Seat Tube Exit Angle	75deg	75deg	75deg	75deg
Head Tube Length	100mm	110mm	120mm	130mm
Bottom Bracket Drop	87mm	87mm	87mm	87mm
Bottom Bracket Height	290mm	290mm	290mm	290mm
Chainstay Length	430mm	430mm	435mm	435mm
Chainstay Length Horizontal	421.1mm	421.1mm	426.2mm	426.2mm
Front-Center	766.8mm	793.7mm	820.4mm	847.3mm
Front-Center Horizontal	761.9mm	788.9mm	815.8mm	842.8mm
Wheelbase	1183mm	1210mm	1242mm	1269mm
Fork Offset/Rake	42mm	42mm	42mm	42mm
Fork Length (Axle-To-Crown)	509mm	509mm	509mm	509mm
Trail	123.4mm very high	123.4mm very high	123.4mm very high	123.4mm very high
Mechanical Trail	112.6mm	112.6mm	112.6mm	112.6mm
Wheel Flop	46.1mm	46.1mm	46.1mm	46.1mm
Tire to Pedal Spindle	219.8mm 170 mm cranks	246.6mm 170 mm cranks	273.4mm 170 mm cranks	300.2mm 170 mm cranks
Pedal Spindle to Ground Clearance	120mm 170 mm cranks	120mm 170 mm cranks	120mm 170 mm cranks	120mm 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.

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Source:https://www.bird.bike/wp-content/uploads/2022/03/Forge-Full-1.png

Geometry