johnlink

From the fall of 2009 until the fall of 2013 I wore a helmet made by Louis Garneau that cost me about $50 that was so comfortable I often forgot I was wearing it. That helmet saved my head in a very slow-speed crash last fall (my front tire got stuck as I went from cobblestones onto a sidewalk). Since then I've tried on many helmets and have bought three, none of which I find comfortable: Specialized Echelon II, Specialized S3, and Mavic Espoir.

Everything I've read about helmets says they're supposed to fit snuggly and not be able to move much when pushed, but I find that I can force them way out of position even when I adjust them to be uncomfortably tight. I think that everyone on each of the teams at the Tour de France wears the same model of helmet, so it seems that I should be able to adjust about any good helmet to fit safely and comfortably. What's the secret to getting a safe and comfortable fit? Is it to add extra padding? Just how snug must the helmet be?

I will be grateful for any advice offered.

Little Darwin

Snug in this case doesn't mean impermeable to force... I am sure that My helmet would move a lot when muscled enough.

Snug to me means tight enough to stay on your head long enough to absorb some of the force in case of impact, and not go flying off when it is needed the most... Basically, it just needs to be tight enough to be on your head when it hits something.

If you hit your head, it is probably a good thing for the helmet to twist some, since the torsional forces would otherwise be applied to your head and neck.

This isn't a comment on style, but as an example... I suspect that the statements you read that say to wear helmets snug is so that helmets aren't worn the same way that some people wear their pants. A snug belt doesn't necessarily mean that someone couldn't pull your pants down if forced, but it should keep the waistband up at your waist in normal conditions. A snug helmet likewise should stay in place during normal usage.

Retro Grouch 

Look at any helmet that you are considering from the top. Some brands are quite round, some are more oval front-to-back. Buy whichever matches your head better.

spdracr39

The idea is for it to stay in place on your head while riding so that you are protected when you hit the ground. If it falls out of place on its own or when you shake your head a little then it is too loose. It does not need to fit like a glove or be so tight as to be uncomfortable. As stated above find one that fits the shape of your head and adjust it so it doesn't flop around and you are good.