Thread-locker – Let’s use this stuff

If you get into the details of this magic stuff, it’s really quite amazing. And do you know how to use it to get the best out of it? We are having an in-depth look at the chemistry, types available and how to use the stuff.

Threadlocker simply stops bolts from rattling loose, this and the piece of mind that your disc brake rotor bolts are not going to whizz out during a gnarly descent make thread-locker a staple nowadays. The often unspoken side advantage is that it actually makes your bolts waterproof thus corrosion proof.  Permatex and Loctite are brand names often associated with this magic stuff. This liquid which is applied to bolts stops the bolt from working loose from vibration. Some bolts which are fastened with low torque can come easily undone due to vibration a perfect application for thread locker.

Thread-locker comes in three basic varieties. Red, Blue and Green. The colour refers to different properties.
Blue is a medium strength meaning it takes a medium amount of strength for it to break / come loose, and applied to the bolt before assembling.
Red is high strength and really locks a bolt in, needs high torque to come undone,, and applied to the bolt before assembling.
Green is penetrating, meaning a slightly more liquid version to penetrate into smaller spaces., applied after assembly.
For bicycles, Blue is your friend. Green, no, Red, too strong.

How does it work?

Some people think of it as glue, but really it’s not, but a lot more sophisticated than that.

First, It needs one thing to work – contact with metal – as it contacts metal the electromechanical reaction starts to polymerise this liquid, thus it gets thicker, sticky and goopy. When not in contact with metal the thread-locker is watery, thin and doesn’t set up.

Secondly,  thread locker is what the smart people call a Thixotropic liquid which means that under a shear stress the liquid becomes thinner and flows more. In this case, it means as you apply it to bolt threads and twist it into a hole it undergoes shear stress and becomes thinner to wick into all the cracks and crevices of the bolt and receiving hole, ensuring good coverage and contact with metal.

The difference between thread-locker and superglue is easily demonstrated. Squirt some thread-locker out on a plastic, wood or paper surface and it will stay wet for a while does not evaporate like superglue. The similarities are that when thread-locker is activated it will cure without air (anaerobically)

Where and how to use it?

• Use the blue one, the red stuff is too strong.
• Use new bolts or clean the treads before using.
• Use just a drop or two, no need for much more.
• Use on metal fasteners 1/4” (6 mm) to 3/4” (19 mm) in diameters and it works best on steel and black oxide steel, but not quite as good on Cadmium steel and zinc. After Blue has been set up for 24hrs it typically takes between 70 -150in lbs to break free on steel and black oxide. This means the bolt can be removed with a tool and a little extra force.

Good places to use this are bolts on disc rotors, stem and handlebar bolts, waterbottle cage bolts, spoke threads when making your own wheels (drop in the nipple top after completion and spin the wheel, don’t use while building).

Bad Places to use this are chainring bolts, threaded bottom brackets, bottom bracket spindles (square taper), pedals, wheel skewers and most drivetrain components. This is because instead you would want a layer of grease protection between the two metal surface to prevent corrosion, galling, squeaks and assist in removal.