Bike tech explained

Your quickfire guide to bike jargon

Fork offset

● How far the front axle – in the middle of the front wheel – is offset from the steering axis. This is an imaginary line that follows the angle of the head tube until it hits the ground.

Groupset

● All the parts involved in braking, changing gear or running the drivetrain. This includes the shifters, brake levers, front and rear brake callipers, front and rear derailleurs (or mechs), crankset, bottom bracket, chain and cassette.

Crankset

● The crankset, or chainset, is the bit that propels the bike and consists of the cranks and one, two or three chainrings. Our three test bikes all have two rings, but single-ring or ‘1x’ setups, paired with wider cassettes, are becoming more common, especially on gravel bikes.

Reach

● The horizontal distance between the centre of the bottom bracket and the centre of the head tube. A longer reach lowers your ride position; a shorter reach means you sit more upright.

Stack

● The vertical distance from the top of the head tube to the centre of the bottom bracket. Taller stack means a more upright ride position; lower stack means a lower (racier) position.

Trail

● The trail figure is derived from a combination of head tube angle and the fork offset and shows how far the tyre’s contact point ‘trails’ behind the steering axis. A small measurement makes for a fast-handling bike; more trail slows down the bike’s steering response.

Thru-axle

● end This that has screws a threaded directly into the frame or fork blade. The larger-diameter axle is more secure than a narrower quickrelease axle as it can’t pop out; it increases stiffness and improves braking.

Wheelbase

● The distance between the centre of the two wheels. The longer the wheelbase, the more stable the bike will be. Gravel, endurance and touring bikes typically have longer wheel bases than you’ll find on a racing bike.