I think it's faster "plug in" at less than 38 kph, and faster "plug out" at higher speeds.

I think you'd be surprised at how warm the lid can get with the plug in, even over short distances. I was racing this weekend in 70 degree weather with the plug in, and sweat was pouring down my forehead into my eyes. I had to reach up and pull the plug out to continue racing, and it was only a sprint.

I would race plug out unless it's really cold. I raced an oly with the plug in and 50 degree weather and was perfectly comfortable the whole time.

From an older post about the PO9:

Jim@EROsports
Jan 23, 14 13:04
Post #53 of 408 (6877 views)


No one had the Split, but my work with Luke McKenzie seemed to confirm it's a fast helmet. The P09 worked on a broad range of riders - more so than most helmets. I don't think it really hurt anyone. It tied or bested the McCLaren on the few riders who tested both. Back in June/July we tested a prototype and found it faster without the visor. We also only tested it with the vent plug out, and at the speeds some of the campers were riding, it would've tested better with the plug in based on our previous testing (we didn't have a plug).

ps......I've had mine for about two years now. Usually keep the visor on and plug in my OLY distance racing....took plug out and visor off for a couple of high heat IMs and HIMs.

What speed were they riding at though.......tri speeds or tt speeds??

Here's a link to the article that first appeared on ST in Jan 2014.

http://www.slowtwitch.com/Lifestyle/A_California_Aero_Camp_4145.html

Found it! 37 km/h, per ERO and Garneau tests. I was off by 1 km/h!

http://forum.slowtwitch.com/...plug%20p-09#p4641693

Thanks for that. Plug out for me this Saturday.