Master Lock Mini U-Lock review

At under a kilo and with a Sold Secure Diamond rating, Master Lock has provided a good blend security and portability

Master Lock Mini U-Lock
(Image credit: Stefan Abram)
Cycling Weekly Verdict

Master Lock’s Mini U-Lock combines an impressively low weight with top notch security, being awarded Sold Secure’s superlative Diamond rating. Much of the weight saving is due to the small size, however it is still large enough that locking up isn’t a challenge every time and being smaller, it is easy to stow the lock in a rucksack. There are some negatives, it doesn’t come with a bike mount and although four keys are provided, there isn’t a replacement service – so try not to lose them. On the other hand, the Master Lock Mini U-Lock is the cheapest Diamond rated lock we’re aware of, so it’s fair not to expect so many extras.

Reasons to buy
  • +

    Under a kilo

  • +

    Highly secure

  • +

    Small, but not too small

  • +

    Four keys provided

Reasons to avoid
  • -

    Doesn’t come with a frame mount

  • -

    No replacement key service

You can trust Cycling Weekly. Our team of experts put in hard miles testing cycling tech and will always share honest, unbiased advice to help you choose. Find out more about how we test.

The Master Lock Mini U-Lock is designed to be a lightweight and portable U-lock which also incorporates a high level of security. Based in the USA, Master Lock has been a producer of padlocks and other security products for over 100 years now.


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Internal measurements and lockable area
Master Lock Mini U-LockKryptonite Messenger Mini (main lock)Zéfal K-Traz U17
8.3cm x 15.2cm | 126cm²9.5cm x 16.5cm | 157cm²11.5cm x 23cm | 268cm²
Swipe to scroll horizontally
Dimensions8.3cm x 15.2cm | 126cm²
Keys4 (no replacement service)
Mount incl.No

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Stefan Abram
Tech features editor

After winning the 2019 National Single-Speed Cross-Country Mountain Biking Championships and claiming the plushie unicorn (true story), Stefan swapped the flat-bars for drop-bars and has never looked back. 

Since then, he’s earnt his 2ⁿᵈ cat racing licence in his first season racing as a third, completed the South Downs Double in under 20 hours and Everested in under 12.

But his favourite rides are multiday bikepacking trips, with all the huge amount of cycling tech and long days spent exploring new roads and trails - as well as histories and cultures. Most recently, he’s spent two weeks riding from Budapest into the mountains of Slovakia

Height: 177cm

Weight: 67–69kg