I will be using the LG P-09 in a few weeks, which, as claimed by LG / tested by eros, is worse with the air vent *plugged* when going slower than 37 km/h, and better / faster with the vent *open* when going faster than 37 km/h. Projected bike would be 5:15 - 5:20.

I kid you not - this is a serious question (if it goes down in ST history like the "how do I make flat coke" post, so be it).

I will be using the LG P-09 in a few weeks, which, as claimed by LG / tested by eros, is worse with the air vent *plugged* when going slower than 37 km/h, and better / faster with the vent *open* when going faster than 37 km/h. Projected bike would be 5:15 - 5:20.

The obvious answer to the subject line would be "look at your bike computer. Number greater than 37? Unplug." But I think the headwinds on the return (or elsewhere) would colour that ... I might be riding far slower than a 37 km/h groundspeed into a strong headwind, which ostensibly would make the plugged option preferable based on the groundspeed that my noggin and the p-09 are experiencing. However, the airspeed / the wind hitting the helmet might be more than 37 km/h, making the open vent preferable.

So I want to selectively plug or unplug the vent at certain points. Not constantly switching - maybe a few times at obvious landmarks.

At what points would be preferred "unplugged" legs of the bike? I would guess:
-First 30 k
-descent from Hawi

Where else?

I kid you not - this is a serious question (if it goes down in ST history like the "how do I make flat coke" post, so be it).

I will be using the LG P-09 in a few weeks, which, as claimed by LG / tested by eros, is worse with the air vent *plugged* when going slower than 37 km/h, and better / faster with the vent *open* when going faster than 37 km/h. Projected bike would be 5:15 - 5:20.

The obvious answer to the subject line would be "look at your bike computer. Number greater than 37? Unplug." But I think the headwinds on the return (or elsewhere) would colour that ... I might be riding far slower than a 37 km/h groundspeed into a strong headwind, which ostensibly would make the plugged option preferable based on the groundspeed that my noggin and the p-09 are experiencing. However, the airspeed / the wind hitting the helmet might be more than 37 km/h, making the open vent preferable.

So I want to selectively plug or unplug the vent at certain points. Not constantly switching - maybe a few times at obvious landmarks.

At what points would be preferred "unplugged" legs of the bike? I would guess:
-First 30 k
-descent from Hawi

Where else?

I agree that the marginal gain of in/out would be offset by reaching up and coming out of position in the first place. I think the greater gain of the system would be leaving it out for the headwind concerns as well as dealing with the heat in Hawaii through better cooling throughout the bike.

I can totally appreciate psychotic what-if'ing. Part of my personality as well.


With a lack of evidence, I'm going to make a wild assumption that the difference between plug in and plug out is pretty small, ESPECIALLY when you're nominally hovering around this transition speed. That'd suggest to me that the benefit of one vs the other is quite low, and while the cost of complicating your bike leg are small as well, I'd stick with picking the side that you're going to spend more of the bike leg in (time-wise, which is even more likely to be the slower part) and leave it as such.

One fewer thing to worry about--set and forget. The less thinking one has to do during a race, the better.

And, Fleck, while your point is a good one, it's quite tangential to the question at hand. Core temps and helmet choices seem to matter, but studies suggest otherwise.

ok. Thanks, all. Not as bad a shellacking as I was expecting!

Fastest "average" across all yaws was no plug and no visor.