Those with the ability to record this data, can any of you get close to 50kph puting out only 345 watts? It might be easier because of the higher mass, but as a relative case, can you offer up your speed vs. wattage data?
Thanks,
-SD
Down a hill? Easy 
On the flat no headwind At 69kg I’ve recorded 360+ watts required to hold 50kph. Though its hard to find conditions in the real world that mean this is anything but a estimate in conditions that infequenctly occure.
Hello,
You might also want to post on biketechreview.com, they have a lot of techies over there.
Styrrell
Yea,
But the tech guys lurk here too, plus they’ll come running over to dispute anything they don’t agree with.
I have a hard enough time keeping up with the few forums I’m alreayed engaged in.
thx,
-SD
Those with the ability to record this data, can any of you get close to 50kph puting out only 345 watts? It might be easier because of the higher mass, but as a relative case, can you offer up your speed vs. wattage data?
Thanks,
-SD
Are we talking track or road here, and is 79 kg the total mass, or just the mass of the rider? What about the environmental conditions (i.e., air density)?
Anyway, this might help put things in perspective: I can think of a number of individuals (mostly women, but at least a couple of men) who can achieve the benchmark you suggest, but none who weigh 79 kg.
P.S. If by any chance you’re hinting at what I think you might be hinting, I’d be happy to provide detailed info/analysis/assistance…just drop me an email.
I don’t want to say ‘impossible’, but I’d have to say, I would find it ‘next to impossible’. I would be capable of doing that (for about 4 minutes…). To give you an idea, (to put it in more human terms!), 28 mph takes me about 260 watts in ideal sea level conditions. That would put me right around those numbers for 50 kph. However, I’m 61-62 kg or so. I just don’t see how it would be possible for someone that size to roll that fast.
wait–is that bike and rider weight, or just rider weight?
I’m 79kg. I’ve done intervals at that kind of wattage on my road bike and…actually on your tri bike (when I test rode it one day). I was moving at 24 to 26mph avg for the intervals. Race wheels, helmets and skinsuits help a lot, but I don’t think I’d be rolling at 30mph with a disc and an aero helmet.
Not for me… 350w gives me around 43-45kph, and I would need a tail wind to get 50kph on that power… I am currently passing through the 79kg barrier 
I don’t think my position is that great however (OK, not great)…
during a 3hour ride i was that for just over 6mins in total
.
If he’s hinting at what I think you’re hinting, he’s only really got to go better than 49.700 kph.
If he’s hinting at what I think you’re hinting, he’s only really got to go better than 49.700 kph.
I’m wasn’t hinting at what you thought I was hinting.
If he’s hinting at what I think you’re hinting, he’s only really got to go better than 49.700 kph.
No–that would be impossible (without aero equipment). I feel pretty confident in saying that.
My guess it that’s the watt/speed for one of the Slipstream guys–and I would have to think that’s total weight (rider/equipment). That’s believable–extremely good, but believable.
Otherwise, at sea level at least, I’m changing my answer to ‘impossible’. That would put the rider at that weight around a CxA of .0175. IOW, Impossible (or nearly so).
Funny enough, I suspect Slipstream has 3-4 guys who could possibly come close to those numbers, though I’m sure everyone here will assume it’s Zabriskie…
roady … errr. hang on there… factor of 10??
If taken from Fort Collins wind tunnel and w/o correction to sea level densities, I make the CdA around 0.220-0.225. That’s quite good but not exceptional
OTOH, if corrected to say 20C and sea level, I make it around 0.185 which IS exceptional. Even more so at 79kg body mass.
I’ve assumed 79kg rider and 8kg of extra bike and kit. Road Crr of 0.004
The mass is male but the w/kg isn’t …
Yeah, that’s why I repeated kept putting the ‘sea level’ part in there!
I was using .0045 for Crr (for more of a ‘real world’) number, and 10 kg for bike and kit (which I also think is more realistic when you toss shoes/helmet etc. into the mix). Also, I’m guessing the w/kg is a baseline for 50kph.
Dave,
I weigh ~79kg and can sit on 345w for quite a while. I can assure you that my average speed with those numbers is nowhere near 50kph, though. It’s more like 45kph on a flat road under decent conditions. And I have a very good position and good equipment. FWIW, I consistently see 50kph on the flats only when I’m well into the 400w+ range. You’d have to be damn tiny and damn aero to squeeze 50kph out of 345 watts.
I weigh in at about 76kg maybe less and at about 360W to 380W I do about 28mph. the problem is I just can’t hold it!
I weigh 83 kg, and I am certainly not a body made for aerodynamics; I’m pretty broad shouldered and bulky (I’m 5’9"). It appears that I’m not too far off that mark, though. This screenshot is from Saturday, TT bike, regular clothes (shorts, jersey, gloves, arm warmers, no aero helmet). It was very close to windless. The highlight was with me in front of our Saturday ride group, trying to tire them out before the sprint point.
That’s pretty slippery for a guy your size. You’ve definitely have a solid position. Here’s the bitch of it, though–take a quick guess (no cheating!) on how many more watts you’d need to go 50 kph?
Yikes! (OK, I cheated)… ~100 watts!!
The hour record’s not gonna be mine any time soon. Heck, probably not the 2 1/2 minute record either.
sea level, negligible yaw, track surface, round and round (not perfectly flat), but certainly no hills.