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Core terms and principles used to understand bicycle geometry, suspension behavior, setup, performance, and service.
Technical entry
Pedal Assist (PAS)
Pedal assist, commonly abbreviated PAS, is an e-bike control system that activates the motor in response to the rider […]
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Q-Factor
Q-factor is the lateral distance between the outside faces of a bicycle’s crank arms at the pedal mounting points. […]
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2x Drivetrains
A 2× drivetrain uses two front chainrings with a multi-sprocket rear cassette. The front derailleur makes large changes between […]
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Head Tube Angle
Head tube angle is the angle of the bicycle's steering axis relative to level ground, expressed in degrees. A smaller number is described as slacker; a larger number is steeper. It affects steering geometry,…
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Layup Schedule
A layup schedule is the manufacturing plan that defines the material, shape, orientation, position, and stacking order of every […]
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Active Braking Pivot
Active Braking Pivot (ABP) is Trek’s rear-suspension architecture built around a pivot concentric with the rear-wheel axle. The chainstay […]
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Chainline
Chainline is the lateral position of a bicycle’s chainring relative to the frame centerline and rear sprockets. Correct chainline […]
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Hub Spacing
Hub spacing is the width of a bicycle hub at the surfaces that contact the frame or fork dropouts. […]
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Wheel Dish
Wheel dish describes the lateral position of a bicycle rim relative to the hub’s installation centerline. A correctly dished […]
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Wheelbase
Wheelbase is the horizontal distance between a bicycle’s front and rear wheel axles, normally measured with the wheels pointing […]
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Fork Offset
Fork offset is the perpendicular distance between a bicycle’s steering axis and the center of its front axle. It […]
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Brake Fade
Brake fade is a heat-induced reduction in braking performance. It occurs when brake pads, rotors, rims, hydraulic fluid, or […]
Read entryTopics intentionally overlap. A drivetrain component can also be a technology; an e-bike system can include components, software, and manufacturing concepts. Cross-listing keeps related reference material discoverable from more than one path.
Technical entries are one part of bicycle knowledge for the life of the bike. Discover bicycles in the Archive, use the Encyclopedia to understand them, then carry useful context into Bike Reports or My Garage.