Correct helmet fit - how much movement is acceptable

Hi All

I’m in the process of looking for a new road helmet and it’s raised a few questions regarding fit. I’m not a new rider (recreational / club / small group rides for last 10 years or so) but having tried a few helmets recently I’m struggling to find helmets I like and that fit really well and it’s made me question how much movement is acceptable.

I currently use a Kask Mojito which has been really comfortable on the head but is looking tired and doesn’t smell very good! I suspected the ratchet system was also maybe not as tight as it used to be. This weekend, after experimenting with new helmets I was shocked by how much movement I got from the mojito. By pushing upwards underneath the rim of the helmet I can push the helmet pretty much off my forehead. It’s like the up and down cradle just allows the helmet to roll up off my forehead. I presume that is not normal.

I also tried a Bontrager Velocis and whilst movement was less I can still move the helmet upwards to expose a few inches of forehead. I can also move the helmet laterally a bit. Same issue with Lazer Genesis. Both, less movement than teh Mojito but not sure either a great fit.

By contrast, I tried a Lazer Century which has a rear dial rather the rollsys on top of head system and that fit very well with very little movement. However, I didn’t like the design or gimmickly light in the back that is meant to be useless. I was surprised by how good the fit was compared to the Lazer Genesis as I thought fit within the same manufacturer the fit would be similar? I also tried my cheap MTB helmets including my sons and fit seemed really solid and difficult to move the helmet (cheap Bell and Scott entry level helmets).

For info, I am using the recommended size guide for each helmet (my head measures 56.5 - 57 cms so I’m usually a medium). I ratchet the dial retention tight and I get the V straps under the ear and the chin strap is two finger tight.

So, questions:

How much movement is acceptable? Should it be absolutely rigid with the only movment being skin creasing or is some upward movement up teh forehead acceptable. My concern - if I can move it with my hand what happens if I hit an object when riding!

How will I know when I’ve found the ‘one’?

LBS’s have limited stock in my area so I’ve exhausted those options and I’m now having to order on line and return. I think I have an oval head. Any suggestions of the brands that are most likely to work? Was next thinking of ordering a POC Ventral Spin if I can get over the unusual looks.

If the Lazer Century fit well but the Genesis did not is there any point to me trying the Z1?
If you have a poor fit from one helmet would you rule out trying other helmets from the same manufacturer?

If you have any suggestions my requirements are:

Good safety (ideally MIPS or SPIN etc)
Good ventilation ( I find Mojito a bit warm on hot days)
Some aero benefit if possible but not essential
Glasses storage dock if possible but this is probably hit and miss depending on your glasses!
Available in white

Many thanks for the advice!!!

Zero movement.

I’m not sure “zero” movement is even achievable or desirable. A helmet would have to be really tight to achieve zero movement. Technologies like MIPs actually introduce movement so the helmet slips a bit on impact. Hair will also provide slip.

As long as you get the right size, snug down the straps and retention system so that the helmet stays on your head, you are good to go IMO. If a helmet can rotate 1/4" or 1/2" in any direction, I don’t think that is a problem. 1/2" still means the helmet is on your head and will protect you from an impact. Don’t over think this one.

Helmets are difficult to assess without long-term use. There’s a tradeoff between tightness and headaches. The whole cycling headache thing is under-appreciated. It affects me almost every single ride. I wear a sweat band and dial my helmet up and down throughout long rides to avoid the dull headache that can happen with any unfamiliar pressure on the cranium. That headache is super-annoying, and I can never tell how persistent it might be until I wear a helmet for a long time in various different environments. For me, I keep the helmet as tight as possible without incurring the headache. I have better luck with Giro helmets because I am “An N of One.” Your mileage will vary and can only be assessed, like most things, through long-term experimentation. Oh, and I forgot to mention FITTING THE HELMET CORRECTLY ON YOUR HEAD! So, so many cyclists don’t get this right. Helmet too far back is classic, too small is also regularly seen. Poorly configured straps–on almost every helmet I see. Don’t do that.

I had to fit a couple of different ones to find the one that fit my crane. For me it was the Abus Gamechanger in a Medium size. With other helmets I had to go up a size (sometimes 2 sizes up) but their inner profile or inner roundness wouldn’t fit my head snuggly. And tightening up with the little ratchet on the back would create unwanted pressure on my forehead.
With the Abus, my head just fits snug, and the ratchet is there to hold it in place rather than to adjust for fitment.
Also, I switched from a vented helmet to an aero helmet and I have to say that it feels much more stable in the wind. My head doesn’t get pushed around when there’s a lot of wind and I don’t end up with a stiff upper back anymore after a long windy ride.
And for me there’s enough ventilation on it.

So maybe think of zero movement as snug without the unwanted pressure. I can promise there is definitely a difference in how it feels.

Hope you find what you’re looking for.

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