Buying a used e-bike: the checklist

A used e-bike can be a bargain — or a bike with a dead battery and a DKK 5,000+ replacement bill. The difference is 20 minutes of systematic checking. Here is the list, point by point, in the order you should work through it on the spot.

1. The battery — the single most important point

• Ask about age and charge cycles. Lithium batteries typically last 500–1,000 full cycles; on many bikes (especially Bosch and Shimano) a dealer can read out the cycle count.
• Test capacity in practice: Ask the seller to have the battery fully charged when you arrive, then watch how many percent a 5–10 km test ride uses. More than 15–20% on flat roads is a warning sign.
• Look for moisture damage on the contacts, and check the battery sits firmly without play.
• Price in the replacement: A new original battery typically costs DKK 3,500–7,000. If the battery is tired, the price should come down by at least that amount.

2. Frame number and ownership

• Find the frame number (usually under the bottom bracket or on the head tube) and have it checked against the Danish police's bicycle register — any bike shop can look it up, and insurance companies have access too.
• Ask for the original receipt or other proof of ownership. No receipt + a seller in a hurry + a cash price far below market = walk away.
• Check that keys for the battery lock and any frame lock are included (ideally two of each).

3. Motor and electronics

• Listen on the test ride: A healthy mid-drive hums evenly. Grinding, clicking or metallic whining under load are expensive sounds.
• Test every assistance level — the assistance should come in smoothly and cut out at 25 km/h without jolting.
• Check the display for error codes and for total kilometres if the bike shows them. Compare with the seller's story.
• Be extra thorough with retrofitted e-kits — they are often illegal in Denmark (over 250 W or missing the 25 km/h cut-off) and always outside manufacturer warranty. See the rules here.

4. The mechanical parts

• Chain and cassette: E-bike drivetrains wear 2–3× faster than on regular bikes — especially with a mid-drive. A worn chain is cheap; a worn cassette + chain + chainring can pass DKK 1,500.
• Brakes: Check pads and discs (grooves or blue discolouration). Hydraulic disc brakes should bite firmly without a spongy lever.
• Tyres, rims, spokes — and on cargo bikes: play in the steering linkage and cracks around the box mounting points.
• Service history: Workshop receipts are gold — they show both maintenance and the real mileage.

5. Is the price right?

Rule of thumb for e-bikes: minus 25–35% after the first year, then roughly 10–15% per year — faster for unknown brands, slower for Nihola, Christiania, Urban Arrow and Riese & Müller, which have strong second-hand markets in Denmark. Look the model up in our database and check the new price before you negotiate: a 3-year-old bike at 60% of the new price isn't a bargain, it's the list price.

The quick checklist

1. Battery: age, cycles, capacity test on a ride
2. Frame number checked in the bicycle register
3. Receipt and keys
4. Test ride through every assistance level — no noises or error codes
5. Chain/cassette/brakes assessed (or price negotiated accordingly)
6. Service history
7. Price compared with the new price and the battery's condition