All you need to know about micrometric or micro-ratchet helmet fasteners


What is a micrometric motorcycle helmet fastener?

The micrometric (or micro ratchet, or plain ratchet) fastener is a relative newcomer to motorcycle crash helmets. It might be new, but it’s a real goodie.

It’s uses a small hard plastic or metal curved strip with teeth on it on one side of the strap. On the other, there’s a corresponding slot with a spring-loaded ratchet mechanism. Insert the strip into the slot and the ratchet grabs onto the teeth, thereby securing the strap.

Couldn’t be easier. Insert the ratchet strip to auto-lock, pull the red tab to release

That means it’s really simple to close and lock micrometric straps; but it’s also easy to open them too. Just pull the red tab connected to the ratchet and it releases the mechanism, unlocking the fastener. Couldn’t be easier.

The strength of a micrometric fastener is in its simplicity to use and, within limits, means that you re-tighten the strap every time. Oh, and in its cheapness to produce.

But it does have a weakness. And that’s in the fact that you only have an inch or so adjustment – the length of the ratchet strip in fact. That’s fine when the strap’s adjusted correctly, but when the strap stretches over time (which it probably will) it’s all too easy to have a micrometric fastener that’s not quite tightened enough.

And that, dear friends, could give you a chance of being one of the 8% of fatal motorcycle accidents where it’s reckoned the helmet comes off!

So, if you ride with a helmet fastened with a micrometric or ratchet strap, if it doesn’t feel tight enough, take a moment to adjust the buckle on the strap itself and not just the micrometric fastener.

Other than that, micrometric’s are great.

Pros of micrometric fasteners

  • Really easy to fasten & release
  • Safe as houses if adjusted correctly

Cons of micrometric fasteners

  • Limited amount of adjustment
  • Need periodical strap adjustment

If you’re wanting a micrometric fastener on your new helmet, you can find all our helmets with micrometric fasteners here.


  1. After having two lids with micromatic I will say I much prefer double D – with some practice you can have a correctly adjusted fit each ride. Also I have lived in a humid climate and the two lids had painted carbon steel micrometric fastener (does anyone make micrometric in stainless?) and adjustment chin strap buckle. The buckle on both corroded to a point where it could have affected the integrity of the strap. All the double D ring fastener lids I have owned had stainless fittings. I suppose micrometric is fashionable now but I note that double D is mandatory for racing car helmets – does bike racing also mandate this?

  2. Well the quick release tab on my Shark Skwal Warhen has just split in half after about 18 months of use, making release a pain.
    Wish me luck sourcing a new one….

    • Never heard of a ratchet wearing out. Very much doubt it would during the expected life of a helmet, but would love to hear if anyone’s worn one out or had to bin off a helmet because of a worn micrometric strap…


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