Originally Posted by canklecat

When I compared Giro and Bell helmets last year they fit and felt pretty much the same. The only significant difference was the straps -- the Giro straps were a little softer and easier to adjust with one hand. I got the Bell because it was the only model REI had in my size and hi-vis yellow at the time.

The Bell Formula MIPS is one of the closest-fitting, smallest outer diameter helmets I've worn. The Giro Foray appears to have a similar appearance.

The only really bulky helmets I've seen that look like mushroom heads are POC. Good helmets but odd looking. I have a POC Omne Air Spin and while it's a little larger in outer diameter than the Bell, it's not quite a mushroom-head looking as the Ventral and Octal models worn by several pro cyclists. The POCs have outstanding ventilation, great for summer wear.

I got my POC in large (my head measures 59cm, on the margin between medium and large), so there's room for a knit cap in winter. My Bell is medium and a tight fit with a knit cap, although it'll handle a bandana.

I'd avoid getting a helmet that's too small for the sake of appearance. I've seen people buy a POC Ventral or Octal that's obviously too small, because they wanted the helmet but not the mushroom head look. The problem with that is it interferes with the SPIN design, POC's version of MIPS, and reduces head protection.