2022 Bird Bikes Forge 150mm 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	65.5deg	65.5deg	65.5deg	65.5deg
Effective Seat Tube Angle, ETT HT Top	76.5deg	76.5deg	76.5deg	76.5deg
Seat Tube Exit Angle	74.7deg	74.7deg	74.7deg	74.7deg
Head Tube Length	100mm	110mm	120mm	130mm
Bottom Bracket Drop	85mm	85mm	85mm	85mm
Bottom Bracket Height	292mm	292mm	292mm	292mm
Chainstay Length	430mm	430mm	435mm	435mm
Chainstay Length Horizontal	421.5mm	421.5mm	426.6mm	426.6mm
Front-Center	766.2mm	793.1mm	819.8mm	846.7mm
Front-Center Horizontal	761.5mm	788.5mm	815.4mm	842.4mm
Wheelbase	1183mm	1210mm	1242mm	1269mm
Fork Offset/Rake	42mm	42mm	42mm	42mm
Fork Length (Axle-To-Crown)	516mm	516mm	516mm	516mm
Trail	125.7mm very high	125.7mm very high	125.7mm very high	125.7mm very high
Mechanical Trail	114.4mm	114.4mm	114.4mm	114.4mm
Wheel Flop	47.4mm	47.4mm	47.4mm	47.4mm
Tire to Pedal Spindle	219.2mm 170 mm cranks	246mm 170 mm cranks	272.8mm 170 mm cranks	299.6mm 170 mm cranks
Pedal Spindle to Ground Clearance	122mm 170 mm cranks	122mm 170 mm cranks	122mm 170 mm cranks	122mm 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