Aerohelmet - Is there a "threshold" benefit?
I'm debating the benefit of purchasing/using an aerohelmet for racing having used only a road helmet for many years (assuming at least equal comfort and heat dissipation for both). Is the benefit only for the > 3.7 watt/kg folks or would a 6:30 IM bike individual benefit assuming that both can hold a comfortable aero position for the same duration.
What do the experienced folks say - is it worth the purchase for mere mortals?
Thank-you.
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That said, Matt is right. Aero helmet (especially if you don't go crazy on the cost) is huge bang for buck. AND, the slower you are the bigger the benefit in absolute terms (minutes) but the smaller the benefit in percentage terms. The math works out this way because we all travel the same distance, as opposed to the same amount of time.
Man, I love having smart people on the Team!!!
Thanks for the feed-back!
Being out of the aerobars is less aero but the benefits of the helmet still stand (more or less) regardless - riding upright with an aero helmet is faster than with a road helmet. If you want to turn your 6:30 IM bike split into a 6:10-1:15 and are willing to invest $150-200 then I think it definitely worth it.
Yes to the aerohelmet, as with other things: regardless of your speed, you need to wear a helmet, have tires in your wheels, tubes inside your tires, bottles on your bike, a singlet, race number, etc. You might as well do due diligence to get the above as aero and slippery as you can.
Is not linear, so the wind is higher as a total percent of resistance when going from 20 to 21 mph than from 16 to 17 mph, and therefore aero gear is more valuable as a percentage of performance improvement as your speeds increase.
@Brett - aerodynamic drag is a function of Velocity squared. (full equation here: http://en.wikipedia.org/wiki/Drag_equation) So, as your speed increases from 10 to 12, an increase of 20% in speed, the drag you have to overcome is increased 44%. Going from 20 to 24, however, again a 20% increase in speed yields the same increase in drag of 44% [22*22 = 576, 20*20 = 400. (576-400) / 400 = 1.44].
To use your numbers:
So, after all that, what do we know. We know that for a specific percentage increase in speed, the drag increases the same percentage. However, the difference in absolute drag, overcome by your POWER PRODUCTION, is a much bigger number (since we are starting from a bigger number.....).
Really simplifying things here, if it takes 200W to go 16mph, the numbers would look like this:
So, 16 to 17 is a larger percentage increase, but a SMALLER absolute number. 20 to 21 is a smaller percentage increase, but a LARGER absolute number.
I hope I didn't muddy things up.....does this make sense?
@Joe, but what color aerohelmet is the fastest?
Sorry, just sat thru 2.75hrs of the Dark Knight. I gots nothin' til mornin'
Pink, of course.
I don't wear my aero helmet above 80F for an IM. I think any aero benefit is offset by heat retention/brain cooking so that you pay back the 5-minutes of aero saving with 20-minutes of dehydration and heat exhaustion.