Potential energy refers to climbing and descending, kinetic refers to accelerations and decelerations. We know that weight matters for both; in addition, even if the route is known and everyone has to follow it, some riders take wider turns, or decelerate through braking and then have to accelerate out of the turns, so they waste energy both by unnecessary braking and then waste energy by trying to make up for it by aggressively accelerating. When you examine differences in acceleration/deceleration, and where they spend their energy, you get a sense for how wasteful some riders are.
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I don’t have a power meter on my TT bike unfortunately, so I am guessing an approximation for my TT. Despite what it says, my FTP was about 350 when I did this, and I take off +/-20 watts for the position to around 330.
I’m 6 feet exactly and around 165 pounds at race weight. Here is my setup and ride. Note that this included three turnarounds since it was on the local flat 20k course.
And the bike:
So it’s obvobviously more than 40 kph, but it should show that would be very doable under 300 watts, probably a fair bit less, if optimized a bit.
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Your 2nd lap is awfully slow 
The 1st one is awesome though 
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But we are talking about TT here and in that case unless conditions change then given identical CdA then the athlete with the highest power should win…allowing for tyres/drive chain efficiency etc…group rides and road racing are of course different…although most TT riders don’t do them (although I like chaingangs and group rides for the social side) because that type of training is of very little use to a time trialist.
Oh, sure…but your previous post sounded like you were saying that great power always trumped a better CdA, which can be true, but not always.
Absolutely agree that w/ identical CdA 9and assuming identical other forces), a higher power output will always prevail.
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I was right under 40kph for this. The course was 3 loops each with 4 corners. You could keep good speed for 3 of the corners but 1 was a bit narrower so had to ease off. Slight headwind one way but nothing too strong.
You can see from the photos I’m in a fairly relaxed position on a cheap road bike with clip bars. So plenty of room for improvement there.
I’m 188cm and around around 73kg.
NP 302
AP 298
Av speed 39.7
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My last TT was about 46.5kph at 378w normalized… Man, I really need to work on getting my CDA down. I’m a big boy at 188cm/95kg. I’ve narrowed my pads and angled my extensions up another 5 degrees to get my shoulders narrower and hands closer to my face, so we’ll see what that does. My estimated CDA for the data below from BBS was .247
Edit: Not sure why TR is showing 417ft of elevation gain…this was a pan flat out and back.
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OT, TR always reports twice the elevation for my Strava and GC rides 
Nice power btw 
The physics of getting you and a bike down the road doesn’t care about normalized power (what a weird name); it only cares about actual power.
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377w average, 378np…basically the same thing in this instance. VI = 1.
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Just for a laugh, same 10 mile course (flattish / rolling out and back with roundabout turn), different weeks, different setups and conditions, a comparison:
TT bike, aero kit, good weather:
42.9 km/h (22.30), 284W
Cyclocross bike (road tyres fitted but full fenders), 38T single chainring, and heavy rain:
37.9 km/h (25:20), 308W
Both off about 60kg / 173cm, 4iiii power meter. Not as big a gap as I’d hoped for, think I could have potential for a lot of aero gains if I’d kept working on it.
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Amazing! Love the story and the pictures! 
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Perhaps this interests the audience as well, some serious world champion datapoints:
It seems to cost the best triathlon men in the world 280W ±10W to reach 40-41kph on an ironman, albeit in 2016. Funny how Frodeno pays 10-20W less than the other guys 
What I like about this page is that it links to their real power data. And because we are talking about world championship, we know they are highly optimized (for 2016 times). Makes me wonder how Frodeno is doing now with all the Swiss Side/Canyon collab.
So my conclusion is that 40-41 kph costs ~280W when highly optimized, when riding without drafting in the crosswind situations of Kona. In Roth in the same year, Frodeno did 43kph, I’m assuming at comparable power. This is consistent with Swiss Side quoting 180/350W for 35/45km/h.
Then again, some of the guys in this thread show data where similar speeds are reached at even lower power. So what is the delta? Less crosswind? Drafting? Absence of hills? Major aero gains in just 5 years time?
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Disc wheels! Haha. Both aero and audible gains. Whoop, whoop, whoop, whoop.
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Is somebody graphing all the day from this thread?
I bet the spread is quite wide
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Mind you, the high crosswinds etc. in kona may make for less than perfect time trialing conditions, where some of the data points in this thread could well be from “perfect” days.
In fact, analyzing my above linked strava activity in mywindsock, the weather score on a scale of 0-500, the value it gave was a very low “49” which it stated was “perfect” time trial conditions.
Put me in kona that same day in 2016 and I may well have gone a bit slower. Would be very interesting to have the comparison though!
I just can’t wait for my next proper time trial ( or even triathlon! ) to get some real world comparisons again.
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Apart from the elevation (>1000m) and the wind, being highly optimised for an 8 hour triathlon is quite different to being highly optimised for a 40km TT. Position needs to be more comfortable. Suit needs to work for swimming and running and not just be the most aero. Transition limits some aero kit choices e.g. You don’t have time to be pulling on tight fitting aero overshoes. Need to carry hydration and nutrition. Might even impact tyre choice, going with a slightly more durable option rather than something super fast but fragile.
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Yeah, biggest difference between my setup above and a triathlon setup is the lack of aero socks ( though if it was a wetsuit legal swim I’d run my aero calf sleeves, but kona is not ) adding my bta hydration ( which SEEMS to be drag neutral according to most testing as it fills the existing gap in my arms, but I haven’t tested it 100% yet ) and perhaps more importantly, my triathlon skinsuit may be less compressive than my cycling skinsuit.
I run this exact position full time for tts though, regardless of distance.
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As an aside - Kessler and Hauschildt just over 5hrs and under 200W…I wish I weighed 61kg…
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Fair enough JoeX, but I’m not pushing 3.6W/kg for 5 hrs, like they are doing!
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