Guide
Which bike lock do you actually need?
Honest and done in two minutes: we'll show you which lock suits your bike and what we, as your insurer, require of your lock.
Updated September 2026
In short
U-lock, folding or chain
With an independent rating like Sold Secure or ART. Cable and spiral locks are cut through in seconds.
Always to something fixed
Lock the frame to a fixed object. A frame lock or GPS tracker alone won't stop a thief.
Around 10% of the bike's value
That's what a good lock may cost, up to about €300 for expensive bikes. For those and for e-bikes, a second lock of a different type is worth it.
For Karl from €29
Depending on your bike's value, your lock must cost at least €29, €45 or €69. The purchase price or the RRP counts.
Lock finder
Three questions, one lock.
We only suggest models that also meet Karl's requirements.
Answer the three questions and we'll show you which lock suits you.
Lock types
Four lock types that protect.
U-lock
The classic: rigid, tough and, with a thick shackle, very hard to crack with bolt cutters. The smaller the shackle, the less room for leverage. The catch: it's the least flexible to lock up.
Folding lock
Hinged steel bars that fold up. It sits compactly in a mount on the frame and is more flexible than a U-lock. But even the best folding locks rarely match a good U-lock.
Chain lock
The most flexible option, even for thick posts or cargo bikes. But a chain only gets secure with hardened links of about 10 mm and up, and by then it's heavy.
Angle-grinder-resistant U-lock
The new top tier: special materials blunt an angle grinder's cutting discs. Heavy and expensive, but the best protection against pros, for example for e-bikes that spend the night outside.
Security ratings
Every lock only buys time.
- Sold Secure
- An independent testing body from the UK. Bronze, Silver, Gold and Diamond stand for ever tougher attacks with ever heavier tools. But the angle grinder only comes into play at the motorcycle level, Powered Cycle Diamond: the lock has to withstand it for at least 90 seconds.
- ART
- A Dutch certification with 1 to 5 stars. For bikes, 2 stars (good) and 3 stars (high theft risk) are what count, and from 4 stars a lock is even tested for motorcycles. Dutch insurers usually require at least 2.
- Manufacturer ratings
- Every brand counts differently: ABUS goes up to 15 (15+ for angle-grinder protection), Kryptonite to 10, Trelock to 18. That helps you compare within one brand, but not between brands.
Models
Locks we recommend.
Karl is an Austrian partner of ABUS. Our recommendations still follow independent tests, not the brand.
U-lock
ABUS
Granit X-Plus 540
A proven classic for everyday city riding. The compact shackle leaves little room for leverage.
- Sold Secure Diamond
- ART, 3 stars
- ABUS 15/15
- Price
- around €85 to €125
- RRP €129.95
- Weight
- 1,5 kg
Qualifies for Karl at any bike value
Trelock
U6
A thick 16 mm shackle at a fair price, rated “good” by Stiftung Warentest in 2023.
- Sold Secure Gold
- Trelock 17/18
- Price
- around €65 to €95
- Weight
- 1,4 kg
Qualifies for Karl on bikes up to €2,500
Kryptonite
Evolution Mini-7
Compact and easy to stow. The cable that comes with it also secures the front wheel.
- Sold Secure Gold
- ART, 2 stars
- Kryptonite 7/10
- Price
- around €50 to €75
- RRP €95
- Weight
- 1,6 kg
Qualifies for Karl at any bike value
Folding lock
ABUS
Bordo Granit 6500K
One of the toughest folding locks. It rides along on the frame in its mount.
- Sold Secure Gold
- ART, 2 stars
- ABUS 15/15
- Price
- around €110 to €150
- Weight
- 1,7 kg
Qualifies for Karl at any bike value
Trelock
FS 580 Toro X-Press
Handy, with a quick-release mount on the frame. The best folding lock in Stiftung Warentest's 2023 test.
- Sold Secure Gold
- ART, 2 stars
- Trelock 15/18
- Price
- around €65 to €100
- Weight
- 1,4 kg
Qualifies for Karl on bikes up to €2,500
Chain lock
Kryptonite
Evolution Series 4 1090
10 mm links in a fabric sleeve that's kind to your paint. Fits around thick posts too.
- Sold Secure Gold
- ART, 3 stars
- Kryptonite 8/10
- Price
- around €60 to €110
- RRP €110
- Weight
- 2,8 kg
Qualifies for Karl at any bike value
Decathlon
C920 L ART 3
Lots of security for the money: the best chain lock in Stiftung Warentest's 2025 test. The trade-off: it weighs around 3 kg.
- ART, 3 stars
- Decathlon 9/10
- Price
- around €60
- RRP €59.99
- Weight
- 3,0 kg
Qualifies for Karl on bikes up to €2,500
Angle-grinder-resistant U-lock
ABUS
Granit Super Extreme 2500
Winner of Stiftung Warentest's 2025 test: it only gave way after just under 15 minutes and six cutting discs.
- Sold Secure Diamond
- Powered Cycle Diamond
- ART, 4 stars
- ABUS 15+
- Price
- around €220 to €300
- RRP €289.95
- Weight
- 2,2 kg
Qualifies for Karl at any bike value
Hiplok
D1000
Holds out against a cordless angle grinder for a long time and is fairly compact. But the small shackle won't fit around every bike rack.
- Sold Secure Diamond
- Powered Cycle Diamond
- ART, 4 stars
- Price
- around €200 to €270
- RRP €299.99
- Weight
- 1,9 kg
Qualifies for Karl at any bike value
Litelok
X1
The lightest and cheapest of the three angle-grinder-resistant U-locks, at around 1.7 kg.
- Sold Secure Diamond
- Price
- around €180 to €200
- RRP €199
- Weight
- 1,7 kg
Qualifies for Karl at any bike value
As of September 2026. Prices are a rough guide to what shops charge. We don't link to any shops.
Locking up right
Leave thieves little chance.
1.Always lock to a fixed object
Lock the frame, ideally together with the rear wheel, to a firmly anchored bike rack, railing or lamppost. For our insurance cover, the fixed object is a must.
2.High and tight
Fit the lock as high as you can and so tight that there's no room for a lever. If it rests on the ground, it's easier for a thief to get bolt cutters on it.
3.Combine two types
A second lock of a different type forces thieves to get out different tools. That takes time, and time is exactly what they don't have.
4.Secure the parts
Secure or swap out the quick releases on your wheels and saddle. On an e-bike, take the battery and display with you if they're removable.
5.Pick the right spot
Busy and well lit beats tucked away. Avoid racks that only hold the front wheel, flimsy fences and signs that can be unscrewed.
6.Document your bike and lock
Write down the frame number, take photos and keep the receipts for your bike and lock. That helps the police, and us, if you ever need to make a claim.
Insurance
What Karl requires.
For a theft to be covered, your bike must be secured with a suitable lock.
Your lock's minimum price
- Bike worth up to €500
- €29
- Bike worth up to €2,500
- €45
- Bike worth over €2,500
- €69
Either the purchase price or the manufacturer's RRP counts as the lock's price. So a bargain is no problem.
And always
- Your bike is locked to a fixed, immovable object with the lock.
- Keep the receipt for your lock, as we may ask for it in the event of a claim.
- Your lock is covered too if you upload its invoice and its value is included in the sum insured.
- Simple cable or spiral locks aren't considered suitable, even if they're expensive enough.
Premium
What would Karl cost for your bike?
What you paid, with all extras.
€5.58per month
€67.00 billed yearly
Includes 8,5% Austrian insurance tax.
You save €6.20 a year.
Common questions
Bike lock questions.
How much should a bike lock cost?
As a rule of thumb, around 10% of your bike's value. For expensive bikes, about €300 is enough, since that's what the best angle-grinder-resistant locks cost. For insurance coverage with Karl, the lock must cost at least €29. For bikes over €500 it's at least €45, and for bikes over €2,500 at least €69. What counts is the purchase price or the manufacturer's RRP.
U-lock or folding lock?
At the same weight, a U-lock is usually more secure, while a folding lock is more flexible and easier to stow. For expensive bikes we recommend a U-lock; for commuters short on space, a good certified folding lock.
What lock do I need for an e-bike?
E-bikes are expensive and popular with thieves. Get a lock with at least Sold Secure Gold or a 3-star ART rating, plus a second lock of a different type. If your e-bike is regularly parked outside, an angle-grinder-resistant U-lock is worth it. Take the battery and display with you if they're removable.
Is there a lock that stops an angle grinder?
Stop one, no. Slow it down for a long time, yes. In the 2025 test by Stiftung Warentest, Germany's consumer testing foundation, the locks lasted anywhere from a few seconds to just under 15 minutes. The best one took the testers six cutting discs. That puts most thieves off, because every minute of noise and flying sparks raises their risk of getting caught.
Is a frame lock enough?
Not on its own. A frame lock (or ring lock) only blocks the rear wheel, so the bike can simply be carried away. For insurance coverage, your bike must be locked to a fixed object. So combine your frame lock with a U-lock, folding lock or chain lock.
Does a GPS tracker replace a lock?
No. A tracker helps you find a stolen bike again and is a good extra. But it can't stop a thief, and you still need a suitable lock for insurance coverage.
Do I have to lock up my bike in the basement too?
Yes. A theft is covered if your bike was locked to a fixed object with a suitable lock. Our terms make no distinction based on where it's parked. So that also applies to basement bike storage, bike rooms and garages.
My bike was stolen even though it was locked. What now?
Report the theft to the police and let us know within 72 hours. We'll need your police report confirmation. Then we'll replace your bike up to the maximum: the sum insured in the first year after purchase, up to 80% of it in the second year and up to 70% from the third. If the thief takes the lock too, we trust what you tell us.
Get covered now
The lock makes it hard for thieves. Karl makes it easy for you.
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