We unravel a few of the more puzzling phrases you sometimes hear when buying a bike…
Aero: Marketing spiel used to point to the aerodynamic efficiency of a bike or particular parts of a bike.
Alloy: Usually refers to aluminium, although in fact all metals used in bike building (steel, titanium) are alloys.
Chromoly: A tough steel made with chromium and molybdenum, aka CrMo or 4130 steel.
Double-butted: Refers to a frame with tubes thicker at the joints (for strength) and thinner in the middle (to save weight). A sign of quality.
Hardtail: Typically used to describe a mountain bike (or MTB) with no rear suspension or shock absorbers.
Monocoque: Often used to describe parts of a carbon bike frame which are molded in one piece rather than assembled from tubes.
Quick-Release (QR) Wheels: These attach to a bike’s frame via a lever and clamp, allowing them to be removed easily without a spanner.
Suspension fork: A type of fork with suspension or shock absorbers.
Thru-axle: Commonly found on MTBs these are increasingly replacing QR wheels on road bikes, offering a wider diameter axle that screws into the frame’s drop-outs or fork ends and provide extra stiffness.
Relaxed geometry: Describes a bike frame with angles and tube lengths that allow a rider to sit in a more upright and thus more comfortable position, as opposed to a race geometry which pulls the rider forward and low into a more aero and less comfortable position.
Torsional stiffness: Also known as steering stiffness, this refers to how much a bike frame ‘gives’. The ‘stiffer’ the bike, the more responsive it tends to be under big power outputs, making it more agile and therefore faster. The downside? The ride also tends to be less comfortable.