OnGuard Mastiff Series Chain Combo Lock

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Product Description

The OnGuard Mastiff chain combi lock is a flexible and versatile bike lock to keep your pride and joy secure in public. Titanium reinforced steel chain links are strong against sawing and cutting attacks, as well as bolt cutters.

A user settable combination gives the OnGuard Mastiff bike lock up to 10,000 variations to deter opportunistic code breakers. You also don’t need to worry about losing keys or forgetting your keys. To protect your bike frame from scratching there is a durable chain cover.

Key Features:

  • Chain 80cm x 8mm With Cover
  • Titanium Reinforced Square Steel Chain Links
  • Steel Ball Click Combo Gear System
  • User Settable Combination With 10 000 Variations
  • Durable Chain Cover Prevents Scratching

    Occasionally, without notice, manufacturers change product design and/or specifications.

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    Chain Lock Guide


    Chain Lock Guide


    For use in medium to high crime areas

    Chain locks are flexible, tough and come in a range of lengths. They opening up a range of versatile locking options that you don’t get with other types of lock. With a chain lock, you’re not limited to fixing your bike to racks and lampposts, but also trees and other oddly shaped objects.

    Chain locks are made of two parts, the steel links that create the chain and the lock. The lock may be integrated into the chain, a separate padlock or even a mini D-lock.

    A burly chain lock can withstand a range of attacks from crowbars to powered tools. However, the trade off is weight. These are the heaviest bike locks that you can get, with some models weighing over 7kg. The heavier the chain, the stronger the links and the more protection you get.


    Portable Chain Hiplok

    Portable Chain:
    1kg – 3kg

    Lighter weight chain locks under 3kg can be wrapped around your seatpost or frame and taken with you on your morning commute. These locks are more practical for daily use, however, will not offer the same level of protection as a sturdier chain.

    Thick Knog Chain Lock

    Stationary Chain:
    3kg – 7kg

    Locks weighing over 3kg are not practical to carry around with you. They do make a great stationary storage solution for your garage or shed, where the chain can be permanently fixed in place. Match a chain lock with a ground anchor for the ultimate protection for your bike at home.


    Chain links are usually built out of steel. However, premium chains will be constructed from hardened steel. By tempering the steel during forming, it becomes harder and less brittle. This makes it much tougher to cut through the links without serious equipment and time.

    Triple heated Boron Manganese steel is exceptionally resistant to cutting style attacks while remaining ductile.

    Thick Knog Chain Lock

    Link Thickness

    Small diameter d-lock

    12mm & Under:

    Chain links under 12mm can be cut with sustained effort with standard bolt cutters if the conditions are right.

    Tip: Lock your bike in an awkward position to make it harder to use bolt cutters.

    Medium diameter d-lock

    13mm – 15mm:

    Only the heaviest duty bolt cutters will be needed for these links.

    Remember, chain links need to be cut twice to break the link. This will take skill, time and effort.

    Large diameter d-lock

    16mm & Over:

    Even the best hand operated bolt-cutters will struggle to tackle these links.

    Tip: Keep your chain and lock off the floor. Freeze spray and a hammer strike can compromise the best chain locks.

    Locking Mechanism

    The Lock

    You’ll find most chain locks either come with an integrated lock or a separate padlock (or mini D-lock). A chain is only as strong as its weakest link, so make sure the lock is tough enough for your needs.

    Look for double deadbolt locking mechanisms that make it much harder to pick or drill the lock open. The thicker the shackle diameter on the padlock or D-lock, the tougher it will be to cut through.

    Close up showing the locking mechanism of the padlock


    Chain Length

    Most brands offer varying chain lengths to suit your needs. Consider where you’re likely to be locking your bike.

    Lengths under 1m will be useful in tight areas such as locking your bike to a rack, fence or post. 1.5m – 2m chains are useful for locking multiple frames to one spot in your garage (you won’t be carrying these length chains with you as they’re too heavy).

    Showing the cable lock in full

    Sold Secure Rated

    A great way to determine the quality of a bike lock is to see if it is Sold Secure Rated. This is a third party, UK independent rating system for bike locks.

    Sold Secure bronze logo

    Sold Secure Bronze

    Coverage: Up to £500

    Sold secure silver logo

    Sold Secure Silver

    Coverage: Up to £1,000

    Sold secure gold logo

    Sold Secure Gold

    Coverage: Over £1,000

    An approved lock is graded as Gold, Silver or Bronze. The rating is chosen by how long it takes to break the lock and the tools needed to break it. If you're planning on insuring your bike, many insurers will state you need a Sold Secure rated lock to make a successful claim.

    These values vary between insurance providers so check the terms and conditions of your provider.

    Frame Protection:

    Metal chain links can quickly scuff your paintwork. Look for chain locks that come with plastic or canvas sleeves to protect your frame from damage.

    It’s also worth choosing a lock (whether integrated or separate) that has rubberised or bump proof shackles and crossbars to ensure your paintwork is safe.

    Showing a close up of the coated part of the lock

    Delivery & Guarantee

    UK Delivery Information

    International Deliveries – Temporarily Suspended 11/11/20

    Note: We are still offering deliveries to the Isle of Man, Scottish Highlands, Scottish Islands, Channel Islands, Isle of Wight, Jersey and Guernsey. 

    Courier Delivery update: Due to the COVID19 situation, we are currently experiencing some delays with deliveries. Our couriers are working around the clock to get your order to you as soon as possible but there is a potential delay of up to 48 hours . Please check your tracking on track your order here.

    Please download the TNT Track and Trace App for iOS here and Android here so you can keep an eye on your delivery and any further updates.

    Please note on the TNT tracking app it may show your delivery status as ‘Collecting’ (as per image below). This means your delivery has left our warehouse and is currently held at TNT main depot and there could be up to a 48 hour delay.

    tnt delivery

    Please keep checking the TNT tracking for further updates. On behalf of TNT we apologise for any delay and inconvenience this may cause. 

    We are committed to offering fast and free delivery, whether you're ordering bikes, accessories or clothing. Our standard delivery service is FREE in the UK, regardless of the size and on all orders over £20.

    Please note that bulky products and bikes shipped to outlying UK regions are excluded from free shipping.

    Please note that Pre-Order dates can sometimes change due to updated stock information.

    Click here for more UK and international delivery information.

    Returns & Warranty

    It's easy to return a product with our 365 day, hassle free returns. 

    We will give you a full refund on any item that is returned to us unused/unfitted, in a resaleable condition and in its original packaging (where possible).

    Please note: For hygiene reasons, we cannot accept returns of facemasks, undershorts or underwear if the item has been removed/unsealed from its original packaging.

    If your item develops a fault or arrives damaged, please contact us first so we can resolve the issue for you as quickly as possible.

    For more information please visit our Returns & Warranty page.