The POC Omne Air Spin may fit. It's oblong and runs larger than spec. My noggin is 23", on the cusp between medium and large so I ordered the Omne in large, but it's just slightly too big for my head -- although I usually wear a bandanna which takes up the slack.

The Omne is made in China to POC specs and runs about half the price of the Octal and Ventral helmets. Right now Nashbar has 'em on sale for $120.

It's a bit heavier than some road helmets due to the thicker foam and "roof" that runs ear to ear. It's more of a well ventilated commuter helmet than a high end roadie helmet. But it looks less bulbous and mushroom-heady than POC's Octal and Ventral, despite having very similar profiles. I suspect it's an optical illusion created by the very different vent patterns. The Octal and Ventral have a very distinctive appearance that some folks hate to love or love to hate. The Omne looks more conventional.

While I got it for errands and casual rides on my hybrid, I ended up wearing it more often on road bike rides in summer because the air flow is so good, better than my Bell Formula MIPS (which isn't bad at all, and a better overall value than the POC).

My only gripe about the POC Omne is the thicker foam and lower fit on the skull means I can see the helmet overhanging my brow when I'm in the drops. It would be unsuited to TT/tri-bikes in the aero bars because of the overhanging brow. But for mostly upright rides it's very good.