A HR athlete's takeaways from the recent power webinar
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This was an excellent, informative webinar. Even though I don't own a PM, I watched it anyway hoping to learn stuff that would benefit my HR bike training.
My takeaways:
- I wanted a PM before, but now I REALLY want one.
- I am so grateful for TrainerRoad. It's not perfect, but it's SO much better than HR training alone.
- I need to prepare for my transition back to outdoor training, where I will no longer have access to power numbers via TrainerRoad.
- While training indoors, I need to start mentally correlating power zones with HR and RPE
- Even in the spring/summer, I am considering doing my shorter weekday ride on the trainer, just so I can train with power via TrainerRoad.
- Coach's explaination of Variability Index (VI) blew my mind. I will never sprint over a hill in a race ever again!
- Did I mention I really want a PM?
Link to webinar: http://bit.ly/L7x3aO
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Also, add in correlating pedal pressure with power zones, such as 85%, 95-100%, etc. Before the winter set in, I was working on that to minimize always looking down at the wattage - and it's a skill that can definitely be learned.
I think it's a good idea to do a shorter ride indoors even in the spring/summer - it can help keep those HR/RPE/pedal pressure correlations accurate. So I'd say you are right on the money there.
Finally, training with power is like doing the jedi mind trick on HR based training - 'this is not the training you are looking for'
On a side note, if my SO doesn't sell his PowerTap to one of our local club members tonight, I'll be posting it to the EN classified tomorrow
@ Brent: My obnoxious computer shut down twice will listening to the webinar. Ugh! Can you tell me, in a nutshell, what coach's explanation of VI is? Thank you, thank you!
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VI stands for Variability Index - which is a gauge as to how wide your power output varies. The ideal scenario is one where you output a specific power constantly over a period of time. That type of riding is less strenuous. By contrast, if you surge, rest, surge, rest - the riding is far more strenuous and you 'burn matches' every time you surge. Same thing with charging up a hill - power output increases massively, but you are burning matches to do so. Unfortunately, the box of matches is only so big - only so many matches. Think of fuel economy in a car - sudden starts and stops lowers your miles per gallon vs steady driving. At some point, your legs have nothing left to give, and you have to ease up and slow down.
Brent may have heard a different explanation, but the one I've heard CoachR give is that if you imagine two riders in a race - both of them same aero profile, same FTP, riding at the same wattage in the flats. When approaching a hill, one surges ahead and up the hill, the other hangs back keeping power output steady. Once at the top, the surger slumps over and has to coast downhill to recover. However, mr steady rider crests the hill (albeit a little later) and now, in order to maintain constant power output, he gets the benefit of speeding up on the downhill and makes up distance on the surger, if not catches him/her outright. They both reach the bottom of hte hill at the same time - but mr steady rider maintained even power output (which is less strenuous) while the surger has burned matches. Eventually, those burnt matches will take its toll ont he surger - which is often on the run or the 2nd loop of an IM course. It's like racing against someone who decides mid-race to run up a flight of stairs and down again - extra effort expended, but for little/no benefit.
Glad you guys found the webinar to be helpful!
Average power = the physics of you riding your bike. You applied watts X to the rear wheel, moving your bike, body weight and tires' rolling resistance down the road for 2hrs and performed an average work effort of 220 watts. An example, using Timmy and Jimmy:
Timmy and Jimmy finish the ride both averageing 220w but their style of riding was quite different.
Normalized power = how tired you made yourself while producing those watts. It accounts for the exponentially higher metabolic cost of higher watts.
We can assign a number to the styles of these two rides:
Variability Index (VI): Normalized Power / Average Power
Jimmy: VI of 1.136
Timmy: VI of 1.045
Timmy and Jimmy get off the bike in T2 at the same time with the same bike split -- they've done the same physics (work performed) for the same bike ride, yielding the same split (FYI, TnJ are identical twins on identical bikes, natch). But Jimmy's style of riding made him much more tired and he will pay on the run.
A good race day VI, for long course racing, is <1.06. 1.02-1.04 is ninja territory. 1.136 is very, very bad. Jimmy is in for a wake up call on the run. </p>
@Ryan - Correlating pedal pressure - I like that one.
So based on pedal pressure, you're able to determine which power zone you're in? That's really impressive.
To me, right now, that sounds like it would extremely difficult to do. But you say it can be learned, so I believe you!
I'll use pedal pressure as my homework assignment to keep my brain occupied throughout the upcoming bike focus block
@Anna - Looks like Ryan and Rich beat me to it
"Pedal pressure": for years I've been trying to feel that. And I''ve got a LONG background of learning about and using pressure sensations from my feet from years as a DH skier. I just have never been able to translate that to my cycling.
What I CAN do is use my sense of how hard my quads and especially glutes are working to tell me what my ball park power is.
I don't think pedal pressure is a tool to help you estimate what your watts are. Rather, you can use it to keep you from spiking watts in high-risk situations. For example, as you come into the base of a hill, pay attention to the pressure on the soles of your feet and keep it constant, as you shift gears to keep your cadence the same as what you were doing on the flats:
Contant pedal pressure + constant cadence = constant power = not spiking (too much)
The errors that 95% of athletes on the course make (and you'll be able to see this dramatically when you're wearing your 3D Power Glasses) is:
But you can throw all that right out the window after 3 hours on the bike! Perceived effort and pedal pressure is not the same at 1hr , 3 hrs , or 5hrs. The pressure yes , but how it feels to you ? NO .... Therein lies the beauty of the PM to keep you honest!
Great idea David. Just created an RSS feed for an Ebay search for "PowerTap". Looks like the going rate is ~$700 for the hub + wheel. Does that sound about right?
It's certainly not an exact science - but when I say it is a skill that can be learned, I'm just referring to being able to use it to sense when you are relatively close to your desired, previously correlated, wattage. I found this out over the summer when I was trying to hit 200W during FTP intervals. Riding outdoors requires a lot of attention on things other than the wattage display. So, over the course of a couple weeks, with practice, I found that I was able to stay in the 200W range (say, +/- 10W) for longer periods of time between glances to my display.
Tim may have a good point about RPE/pedal pressure after 3 hours.. I've not tried it on a ride that long, so I have no experience with that