Glossary
Plain-language definitions for the terms that show up across our guides — jump to a section, or use your browser's find-on-page for a specific term.
A motor built into a wheel hub (usually the rear) that drives the wheel directly. Simpler and cheaper to service than a mid-drive motor, and perfectly adequate for flat-to-moderate commutes — most e-bikes under $1,500 use one.
Best E-Bikes for Commuting Under $1,500 →A motor mounted at the bike's bottom bracket that drives the drivetrain rather than the wheel directly. Handles steep hills and mixed terrain more efficiently than a hub motor, at a higher cost — common above roughly $2,000.
Best E-Bikes for Commuting Under $1,500 →Pedal-assist only (no throttle), with motor assistance cutting off at 20 mph. Has the widest legal access to bike lanes and multi-use paths of the three classes.
Class 1 vs. Class 2 vs. Class 3 E-Bikes →Throttle-capable — the motor can propel the bike without pedaling — with assistance capped at 20 mph. Path access is similar to Class 1 in most states.
Class 1 vs. Class 2 vs. Class 3 E-Bikes →Pedal-assist up to 28 mph (some models also allow throttle to 20 mph). Often restricted on multi-use paths and greenways due to the higher speed differential with pedestrians and traditional cyclists.
E-Bike Class Laws by State →A rigid, hardened-steel shackle lock — the baseline standard for commuter bike security. Resists bolt cutters and prying better than a cable lock.
Best Bike Locks →A hardened-steel chain with a separate lock body. Similar security to a U-lock with more flexibility to lock around awkward frame shapes or through both wheels, at the cost of more weight to carry.
Best Bike Locks →Articulated hardened-steel bars that fold compactly. Comparable security to a U-lock from quality brands, in a smaller carry footprint.
Best Bike Locks →A steel cable, usually with a combination or key lock. The weakest common lock type — easily cut with basic tools — and should only be used as a second, supplementary lock, never alone in public.
Best Bike Locks →A U-lock or similar that unlocks via a phone tap (NFC) or included card instead of a physical key. Genuinely convenient, but adds a battery you need to keep charged.
Best Bike Locks →The clearance between a rider's inseam and the bike's top tube when standing over it. A more reliable sizing check than age or height alone, especially for kids.
Bike Size Selector →The measurement from the ground to the crotch, standing. Used with standover height to size a bike correctly — our bike size selector does this conversion for you.
Bike Size Selector →A bike's size designation, given as a letter (S/M/L/XL) or a number in centimeters. Sizing charts vary by brand and bike type, so treat them as a starting point, not a guarantee.
Bike Size Selector →For kids, wheel size (12" up through 24") is the primary sizing indicator and scales with age and height, from balance bikes up to youth mountain bikes.
Best Kids' Bikes by Age →The two common adult mountain bike wheel sizes. 29" rolls over obstacles more easily and holds speed better; 27.5" is a little more maneuverable on tight, technical trails. Neither is objectively better — it's a real feel preference.
Best Mountain Bikes for the Money →Brakes that use fluid to transfer braking force. Give more consistent stopping power with less hand fatigue, and self-adjust as pads wear — the higher-end standard.
Best Mountain Bikes for the Money →Cable-actuated disc brakes. Cheaper and easier to service at home without special tools, but need more frequent manual adjustment and give up some stopping power versus hydraulic.
Best Mountain Bikes for the Money →A switch or lever that firms up a suspension fork for efficient pedaling on smooth ground or climbs, then releases it again for the descent.
Best Mountain Bikes for the Money →A mountain bike with front suspension only (no rear shock). Lighter, cheaper, and lower-maintenance than full suspension — enough for most casual and moderate trail riding.
Best Mountain Bikes for the Money →A mountain bike with both front and rear suspension. Improves traction and control on aggressive, technical, or downhill-focused riding, at a higher weight and cost.
Best Mountain Bikes for the Money →The standard frame material at most price points — light, stiff, and inexpensive to manufacture, though it transmits more road vibration than steel or carbon.
Best Road Bikes for Fitness & Commuting →A steel alloy frame material. Weighs a bit more than aluminum but rides smoother over rough pavement.
Best Road Bikes for Fitness & Commuting →The lightest common frame material, with the best vibration damping — at a significantly higher price. Matters more for fitness mileage than for a daily commute.
Best Road Bikes for Fitness & Commuting →