Buying a Bike or E-Bike Online: Sizing, Specs and What Happens After Delivery

Buying a bike online widens your choice, but you can't test ride it first. A bit of measuring and spec-reading up front avoids most of the problems.

Start with the type of riding you'll actually do

Pick the bike for the riding you do most often, not the riding you imagine doing once a year.

Get the frame size right

Every brand publishes its own size chart, and sizes are not consistent between brands. A "medium" from one maker can fit like a "large" from another, so always use the chart for the exact model you're looking at.

1. Measure your height without shoes.
2. Measure your inseam: stand against a wall with a hardback book pressed up between your legs, spine against the wall, and measure from the top of the book to the floor.
3. Compare both numbers to the chart. Many charts list a height range per size; some also list inseam.

A few points to watch:

• Sizing units vary. Road and gravel bikes are often sized in centimetres, mountain bikes in inches or S/M/L, and children's bikes by wheel size.
• Standover height matters. You should be able to stand over the top tube with both feet flat and some clearance.
• Between sizes? The smaller size usually feels more nimble, the larger more stretched out. Check what the brand suggests.

Reading e-bike specs

An e-bike adds a motor, a battery and some extra jargon.

• Motor position. Hub motors sit in the front or rear wheel and are common on lower-priced and city e-bikes. Mid-drive motors sit at the pedals and work through the gears, which tends to feel more natural on hills.
• Battery capacity (Wh). Watt-hours tell you how much energy the battery holds. If only volts (V) and amp-hours (Ah) are listed, multiply them: a 36V, 10Ah battery holds 360Wh. More watt-hours generally means more range, but also more weight and cost.
• Range claims are estimates. Advertised range depends on rider weight, hills, wind, temperature, tyre pressure and how much assistance you use. Treat the figure as a best case and plan for less.
• Removable battery. Useful if you can't park near a power socket. Check that replacement batteries and chargers are available.
• Weight. E-bikes are much heavier than ordinary bikes, which matters if you have stairs or a car rack.

E-bike rules differ by country

• In the US, many states use a three-class system based on whether the motor assists only when you pedal or also has a throttle, and the top assisted speed. Which classes are allowed on bike paths or trails depends on your state and local area.
• In the UK, e-bikes that meet the rules for an "electrically assisted pedal cycle" (EAPC) can be ridden like ordinary bikes. These rules set limits on motor power, assisted speed and rider age. Bikes outside the rules may be treated as motor vehicles.

Check the official guidance where you live before buying, especially for throttle-equipped or high-powered models. This guide isn't legal advice. If the bike ships from abroad, see our international shipping and customs guide.

Plan for delivery and assembly

Most bikes arrive in a large box, partly assembled. Typically you'll need to fit the handlebars, front wheel, pedals and seatpost, and sometimes the mudguards and lights.

• Check what tools are included and whether a fully built option is offered.
• Pedals are side-specific. The left pedal usually has a reverse thread, so it tightens anticlockwise.
• If you're not confident, a local bike shop can check brakes, gears and bolt tightness.
• Inspect the box on arrival and photograph any damage before you unpack.

Servicing and returns

• Find a local shop willing to service it. Some shops won't work on certain e-bike systems.
• Check the warranty and whether it requires regular servicing.
• Read the returns policy: who pays return shipping, whether the bike must go back in its box, and whether riding it counts as use. Keep the packaging until you're sure. If something goes wrong, our guide to refunds and chargebacks explains your options.