OnGuard Mastiff 8020

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Lock Type
6.28, 5.70 lbs
Diameter / Thickness
10 mm
42 Inches
Titanium-reinforced Steel

Summary of Reviews

We have read all expert and user reviews on the OnGuard Mastiff 8020. In summary, this is what cyclists think.

9 reasons to buy

  • A tester says the Mastiff 8020 is able to be carried over your shoulder.
  • The 10 mm-thick, titanium-reinforced chain resisted a tester’s angle grinder.
  • A reviewer says that the Mastiff 8020 is long enough to reach around many posts.
  • The Mastiff 8020 is long enough to lock two bikes.
  • With a keyhole at the chain’s end, a tester says the Mastiff 8020 locks efficiently.
  • The Mastiff 8020 comes with five keys, including one that’s illuminated.
  • If Mastiff 8020 owners register online, replacements for lost keys can be ordered.
  • OnGuard’s Anti-Theft Offer will reimburse the value of a stolen bike up to $2001.
  • Owners feel that the Mastiff 8020 is beefy enough to intimidate many thieves.

4 reasons not to buy

  • Sold Secure gives this lock a Bronze rating, meaning it can be broken in 1 minute with hand tools.
  • A number of owners reported that their key became permanently stuck in the lock.
  • For multiple owners, the lock mechanism broke after short-term use.
  • At 6.28 lb, the Mastiff 8020 is significantly heavy.

Bottom line

OnGuard’s Mastiff 8020 is a heavy chain lock with robust, titanium-reinforced links. One tester’s angle grinder ran out of battery before it could cut through them. A number of owners felt that it served as a strong deterrent. Nevertheless, in tests, the lock mechanism could be destroyed in under a minute using basic hand tools. OnGuard does provide an ‘Anti-Theft’ reimbursement program, but conditions are strict and it involves a fee that must be paid by check. In addition, a number of users experienced stuck keys and the disintegration of the lock mechanism. You’re better off with the Mastiff 8019, which uses a padlock.

Expert Reviews

10/100 based on 1 rated expert review
The Best Bike Lock

Onguard 8020 Mastiff: Is This the Worst Bike Lock Ever?

Ideally, the best bike lock would be light and cheap and strong. So does that mean that the worst bike lock would be heavy and expensive and weak? Because if it does, then the OnGuard 8020 Mastiff is a definite contender!

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Slide Hammer vs. OnGuard Mastiff Bicycle Chain Lock

So in probably one or two minutes, we were able to take this right apart.

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OnGuard Mastiff Bicycle Chain Lock Picked

Picking this open really didn’t take very long but because it does require a very special technique for picking, I really don’t think lock-picking is a likely real-world threat. However, I do have a few concerns about the construction of this lock.

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User Ratings

90/100 based on 206 ratings
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Bike Lock Comparison

OnGuard Mastiff 8020 in comparison to averages

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