# Bike glossary

**Reach** — The horizontal distance from the bottom bracket to the top of the head tube. More reach = a longer, more stretched-out bike. The most useful single number for comparing sizes across brands.

**Stack** — The vertical distance from the bottom bracket to the top of the head tube. More stack = a taller front end and a more upright position.

**Geometry** — The angles and lengths of a frame. It decides how a bike fits and handles: relaxed (endurance) geometry is comfortable and stable, race geometry is low and quick.

**Endurance geometry** — A road or gravel frame with more stack and less reach than a race bike, for a more upright, comfortable position on long rides.

**Head angle** — The angle of the fork to the ground. Slacker (lower) angles are stable at speed and on descents; steeper angles steer quicker.

**Standover height** — The height of the top tube where you stand over the bike. It should be a few centimetres below your inseam.

**Inseam** — Your inside leg length, measured barefoot from the floor to your crotch. Used together with height to choose a frame size.

**Frame size** — Road and gravel bikes are often sized in cm (e.g. 54), mountain bikes in letters (S–XL) or inches. Sizes are not standard between brands.

**Groupset** — The gears and brakes as a set: shifters, derailleurs, crankset, cassette, chain and brakes. Shimano (Claris → Sora → Tiagra → 105 → Ultegra → Dura-Ace) and SRAM are the main makers.

**1x / 2x drivetrain** — The number of chainrings at the front. 1x ("one-by") is simpler with one front ring and a wide cassette; 2x has two rings for closer gear steps.

**Cassette** — The cluster of sprockets on the rear wheel. A wider range (e.g. 11–50) means easier climbing gears.

**Hub gears** — Gears sealed inside the rear hub (e.g. Shimano Nexus, Enviolo). Very low maintenance and you can shift while stopped — popular on city bikes.

**Belt drive** — A carbon belt instead of a chain. No oil, no rust, very long life; needs a special frame and usually hub gears.

**Hydraulic disc brakes** — Brakes that use fluid to push pads onto a rotor at the hub. Strong, consistent in the wet and light to operate — the standard on most bikes above entry level.

**Suspension travel** — How far the fork or rear shock can compress, in mm. XC ~100 mm, trail 120–150 mm, enduro 160–180 mm.

**Hardtail** — A mountain bike with a suspension fork but no rear suspension. Lighter, cheaper and simpler than full suspension.

**Full suspension** — A mountain bike with suspension front and rear, for more grip, comfort and control on rough trails.

**Dropper post** — A seatpost you can lower with a lever on the bar while riding, so the saddle is out of the way on descents.

**Tubeless tyres** — Tyres run without inner tubes, with sealant inside. Fewer punctures and you can run lower pressures for grip and comfort.

**Tyre clearance** — The widest tyre a frame and fork can fit. Important for gravel bikes: 40 mm+ lets you ride rough surfaces comfortably.

**Mounts** — Threaded holes on the frame and fork for bottle cages, racks, mudguards and bags. More mounts = more versatile for commuting and touring.

**Mid-drive motor** — An e-bike motor at the cranks that drives the chain, so it uses the bike's gears. Best for hills and a natural feel (e.g. Bosch, Shimano, Yamaha).

**Hub motor** — An e-bike motor inside the front or rear wheel hub. Simpler and cheaper; fine for flat city riding.

**Torque sensor** — Measures how hard you pedal so the motor adds power in proportion — smooth and natural. Cheaper cadence sensors just detect that you're pedalling.

**Watt-hours (Wh)** — Battery capacity. 400–500 Wh suits most commutes; 600–750 Wh is better for hills, cargo and long rides.

**Pedelec (EU)** — The EU e-bike class: pedal assistance up to 25 km/h with a 250 W motor, treated like a normal bicycle. S-pedelecs assist up to 45 km/h and need insurance and a number plate.

**E-bike classes (US)** — Class 1: pedal assist up to 20 mph. Class 2: throttle up to 20 mph. Class 3: pedal assist up to 28 mph. Rules on where each may ride vary by state.

**Bikepacking** — Multi-day riding with bags strapped to the frame, bar and seatpost instead of racks — light and suited to gravel and trails.

**Longtail** — A cargo bike with a stretched rear end for seats, bags or a second rider. Handles much like a normal bike.

**Box bike (front-loader)** — A cargo bike with a box in front of the rider, often with a bench and rain cover for kids. Carries bulky loads; longer and wider than a longtail.