Power vs Speed
Hey all,
I am going to ask the dumbest questions in the world. So with my FTP and VO2 max, i am between a 175 and 208ish. Howevery if i am racing, i am keeping my power between 145 to 155 based on the race distance. With these watts, i am averaging over 18 to 19 mph. ?!?!?! So when i see folks pushing 300 watts for their FTP, what speeds are we speaking about for a HIM? 24 to 28MPH?
My biggest confusion is that people have such higher watts than me, but they are around the same times and speeds during a HIM. WHY? What the heck am i doing wrong? I want to display 200+ watts for my FTP. I feel like such a slacker and a weakling.
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EG, someone with FTP of 300 who is on a road bike with drop bars, round tubes, spoked wheels, weighing 220#, may verywell go slower than someone with tricked out tri bike, who weighs 150#, has geat aero position, and an FTP OF 200.
Bottom line, very hard to compare individuals as there are so many variables. Best to focus on things like position, interval training and race day execution.
Jonathan....I understand your question completely. What you are REALLY asking is, what if my PM is not accurate....and I'm really much stronger than the numbers indicate. I have the same questions recently. I am going to call Saris soon to see if my PM needs to be changed/rebuilt. Because...when I did IMTX in May, my FTP was 220. I'm sure of that. When I calibrated, I would usually see 506, 507, 505 pretty consistently (not sure what to call this number....it just shows up when I hit "calibrate"). After IMTX, when I started riding hard again, when I calibrated, I would see 557, 560....never again have I seen 506, 507, 508. See Coach P's thread re how to maximize trainer time, where Shaughn Simmons mentions having to have his PT rebuilt because these numbers start changing.....
So, I noticed that while my FTP dropped after IMTX, my typically speed did NOT (speed at FTP or in Z3, whatever). So, this would be explained (possibly) by my PT not being calibrated correctly anymore. I did a "hard calibrate" when I first got it, b/c I thought it was too low based of Trainer Road estimates of my FTP. When I did the hard calibrate, it was within the range of standard error though.
Have you done that "hard calibrate" procedure (if you have a PT)? You basically lock the brake/wheel, apply a load to the pedal (weight of some sort) and then look at the number on your head unit. Calculation then required to see if it's accurate. Youtube/Google it or check Saris site for details...can't remember them now.
So, it is possible that although your PM may be perfectly CONSISTENT, it may not be ACCURATE. Doesn't matter as far as how to train/race, but sure does make your W/Kg look different if your PM is calibrated too "low".
Does that help? If you figure something out, would love to hear more...
JL
The long answer is much more complicated. First, Aerodynamics has a lot to do with it. If Joey big quads puts out 300 Watts while sitting upright most of the time without a clean bike setup, then he will not be faster than Tiny Timmy who stays aero and has a clean bike setup pushing lower watts.
If it's a flat course, then Absolute Watts matter more, but if it's a hilly course, then W/Kg matters more... So your weight sometimes matters as much as how many watts you can put out.
Then there's the whole "physics" of air resistance which increases as a function of your speed-squared. What that means is that on a flat course, as you go faster (say north of 20mph), the amount of power required to go just 1 mph faster is A LOT more... but at say 8 mph, the amount of incremental power needed to go 1 mph faster is just a little bit more.
So lets put some HUGE generalities around your question with some "guesses". (you can get much closer with some of the software out there, but I'm too lazy to do that for you so I will just guess and hope I'm close.) You say at ~150W you go ~18.5mph. I think I remember Juan Vergara doing a 5:21 bike split at IMFL (~21mph) which is pretty flat but a bit windy on ~170-175W and he's roughly your size. I averaged ~24.5mph at Challenge AC on ~235W for the first several hours until the wind picked up a bunch (and I was ~185lbs and about as aero as you could get with a super clean setup - think aero kit, shoe covers, and no bottles other than a torpedo). To get to ~27mph which some of the Pro's can pull off, you're looking at ~325-350W for ~4hrs. But to get above 30mph, you'd need well north of 400W...
Jonathan,
I think it's been mostly covered. Beyond a calibration issue with your power meter it's more like what are you doing right. If you are making the same times and speeds in HIM as others with much fewer watts then you have a good set up.
As for pushing the bigger watts that's what the OS is for or maybe a bike focus or big bike weeks to help you push up your numbers. Use me for example my best watts coming out of the OS is 260 my lowest weight was around 220lbs or (100kg) so I only have a 2.6 w/kg. If I recall correctly in my last IM race rehearsal I was around or just below average 18MPH off 175 watts. Gravity's is a bitch on fat boy's.
This is all really good info . It shows how important the aero factor is. It also tells me more money needs to be spent on becoming more aero
My FTP at that point was around 320W, my height is 178cm and my weight was around 75kg at that point. I did use a very solid aero-gear including helmet, FLO-Disc + FLO60 on a Scott Plasma CR1.
Weather conditions were cold (which increases air density) and wet (which reduces rolling resistance). Race took place at 700m above sea level.
The 90,2k long double-lap course only had a total elevation of 570m (which is almost totally FLAT for a venue located directly in the alps!)
I averaged 261W (IF0.85) and hit a NP of 270W (VI 1.03) which was good for the fastest bike-split (2:13:56) of all non-PRO starters averaging a bit above the magic mark of 40km/h.
Here is a very nice article about the legendary Miguel Indurain and how he and his crew prepared for his 1h-TimeTrial World-Record back in 1994! Unfortunately the page is in german but Google may translate it pretty well normally.
http://www.radpanther.de/index.php?id=57
For getting an understanding about the power needed to achieve a certain speed on the track look at this table:
1st column is the speed in km/h
2nd and 3rd columns reflect the needed power for a guestimated Cwa of 0,35 and 0.30.
4th column is the power needed if you would have Indurains Cwa
Here is a sad reminder of how bad I suck on the bike with a 2.68 W/Kg
(from the link Stefan posted above)
Well Steve that's why we are in the OS. My problem for the most part has been the denominator of the equation, but I could use some more in the numerator category as well.