Bike tech explained

Your quickfire guide to bike jargon

Bottom bracket

● Connects the chainset (aka crankset) to the bike. It sits inside the frame at the junction of the down-tube and seattube and includes bearings that allow the chainset to spin freely. Types and sizes depend on the brand.

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 between the top of the headtube to the centre of the bottom bracket. Taller stack means a more upright ride position; lower stack means a lower (racier) position.

Trail

● is combination derived The trail from figure of a headtube offset. angle This and measure fork shows the tyre’s contact point ‘trailing’ behind the steering axis. A small measure of trail makes for a fast-handling bike; more trail slows down the steering response.

Headset

● This refers to the parts at the top and bottom of the frame’s head-tube, into which the handlebar, stem and fork are fitted.

Groupset

● The groupset is 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.

Ultegra Di2

● generation (digital intelligence) Shimano’s integrated Di2 new brings communication wireless from the shifters to the derailleurs. The derailleurs work from a battery mounted inside the seat-tube and wired to both. New Ultegra Di2 is 12 speed which means it’s compatible with both pro-level DuraAce Di2 and the new 105 Di2.

ETAP

● This is SRAM’s electronically controlled gear system, which has evolved from the brand’s original mechanical ‘double tap’ system.