The short version: buy a hardened U-lock (or a heavy folding lock), spend a bit more than feels comfortable, and learn to lock the frame and a wheel to something immovable. The lock matters less than how you use it.
Lock types, fastest to most secure
Cable locks look like security and aren’t — bolt cutters or even strong snips go through most in seconds. Use a cable to tie down a wheel or saddle, never as your main lock.
The marker is the floor worth buying: a good folding lock. Anything to its left (cable, cheap combos) is a deterrent, not real security; compact hardened U-locks and thick hardened chains sit further right.
The three worth buying:
U-lock (D-lock)
The standard- Hardened shackle resists bolt cutters and leverage
- Compact leaves no room for a tool inside
- Most security for the weight
Folding
Everyday middle ground- Packs down small, carries easily
- The good ones are seriously tough
- A little less secure than a U-lock
Chain
Park it and leave it- Thick, hardened chain is very secure
- Good for a bike that lives outside
- Heavy for daily carrying
What “secure enough” means
Don’t judge a lock by its marketing. Look for an independent security rating: in the UK, Sold Secure (Bronze, Silver, Gold, Diamond); in the Netherlands, ART. These bodies actually attack the locks — a higher rating means more time and noise to defeat, which is the whole game, since a thief wants neither.
A rough rule of thumb: spend around 10–20% of the bike’s value on locking. On an e-bike or anything expensive, go up a tier and consider two different locks (a U-lock plus a folding lock or chain) so a thief needs two tools.
How to lock it (this matters more than the lock)
- Lock to something fixed and solid — a proper bike rack bolted to the ground, not a flimsy sign or a post the bike can be lifted over.
- Put the U-lock through the frame and the rear wheel, around the rack. The rear wheel is the expensive one.
- Fill the space inside the U-lock with bike and rack — less air, less room for a tool.
- If your front wheel or saddle is quick-release, take it with you or secure it with a cable or a second lock.
- Point the keyhole down or inward so it’s harder to attack, and lock the bike where it’s busy and well-lit.
What no lock can promise
- No lock is unbeatable — a thief with time and the right tool wins. Aim to be slower and louder to steal than the next bike.
- A cheap lock on an expensive bike is a false economy, and so is a great lock used badly.
- Register your bike’s serial number and photograph it. It won’t stop a theft, but it helps recovery and insurance.
This guide covers durable, well-established lock advice; the security-rating schemes named (Sold Secure, ART) are independent testing bodies you can verify directly.
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