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Old 09-24-19, 01:02 AM
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canklecat
Me duelen las nalgas
 
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Bikes: Centurion Ironman, Trek 5900, Univega Via Carisma, Globe Carmel

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You're not overthinking it. Helmet fit is critical. And helmets of the appropriate size don't all fit the same.

My skull is 59 cm and I can wear medium or large depending on the helmet. I have to try 'em to find out.

I have Bell helmets in medium and large and with both the adjustment dial on the rear contacts the point of the external occipital protuberance. Ideally it should fit slightly below there in the hollow space between the base of the skull and neck. That would help resist tipping.

My POC Omne Air Spin in large fits as expected, with the harness dial right in that hollow area between the external occipital protuberance and neck. Snugged up, it feels secure.

However POC helmets are already like head mushrooms, wider than most because they use thicker EPS foam and polycarbonate shells. Like other users I find the overhanging brow just visible at the top of my peripheral vision, which can hinder my forward view from the drops unless I crane my neck up. Good protection and better ventilation than my Bell helmets.

Some road helmets seem minimalist compared with mountain bike helmets. My Bell Formula MIPS runs on the minimalist side, while the POC is noticeably larger in external diameter. The Omne Air Spin is more of a commuter helmet but with excellent ventilation where most commuter and skater helmets have terrible ventilation from a few dinky holes -- they look like bowling balls. I like the POC so well I've been using it on my road bikes on hot summer rides for the ventilation.

POC uses its own "SPIN" system rather than licensing MIPS. Seems to work the same way. I know the MIPS system in my Bell helmet works -- found out the hard way earlier this year. A railroad crossing arm came down unexpectedly quickly as I was passing a railroad crossing slowly. Hit my helmet, which deflected it, with the outer protective shell tipping while the harness remained in place. No harm to helmet or skull. POC just uses a different, less sophisticated looking but less cluttered approach, which probably helps with ventilation.

The POC Ventral and Octal run a bit smaller in outer diameter, so if you don't mind the hefty price they're worth considering.

Last edited by canklecat; 09-24-19 at 01:06 AM.
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