Glossary
Bike jargon, decoded
30 terms you'll meet on spec sheets, in plain English.
- 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.