Racing with average power and splits to estimate NP

matthewbward

I use a LYC with my Powertap that won't give me NP or TSS or anything like that.  Basically I just get Average Power.  I read something a while back from Jordan Rapp (can't find it now) about splitting his race into 1/4ths or so and tracking his AP to optimize his power output when he rides.  It seems like a pretty good idea.  My assumption would be that over many smaller intervals (10 miles or so, maybe) I could pedal to a predetermined AP, get a lower VI, and have a better indication of NP while racing.

Has anyone tried anything like this?

The reason I ask is that sometimes I feel like I'm hitting my NP goal (and TSS by extension) during a ride, only to download it later and see I didn't push hard enough.

 

Paul Hough

@ Matt - I'm new to outdoor power and I'm not sure what all is available on my Edge 500. But I have an example of how targeting a power number can help. I rode the same 57 mile loop with ~ 3,000 elevation gain on Sunday 15 April and again on Saturday 21 April. On the 15th, the ride took me 3hrs 2 mins and when I downloaded the data I had an average power of 196. On that ride, I was sort of following my power and trying to stay in Zone 3. Six days later, I did it again as a HIM race rehearsal and specifically chased 222 watts on a 3 second avg power reading which is 85% of my FTP. With constant elevation changes, I was frequently over and under but I watched it the whole ride. This time I finished in 2hrs 51 mins. I expected my avg power to be higher but when I uploaded to Garmin Connect, it was 192 - 4 watts lower. So less overall work and heck of a lot faster. So while I don't know the net power or VI, etc, just going for a target power number was very effective.

[Deleted User]

@Matt - I've noticed the same thing. I think I am hovering around the target wattage while riding, but am surprised to find that I often undershoot it. My theory is that on a trainer, you are always working - you have to keep the pedals moving and pushing those watts at all times. While outside, there are probably more little "micro rests" - you can lay of the power momentarily but momentum keeps you moving along, and you may not notice the momentary let up. This adds up, and your NP is less than you thought it should be, based on your experience watching the LYC on a trainer. I'm no expert, and this is just a theory. I think practice keeping the power up, and maybe shooting slightly high, could fix the problem.

Peter Greagg

Hi Matthew — I use the LYC with my PT wheel. I have been using power for about 18 months.
What I have found is that in a race or RR, if I target, say 185 watts, I end up around 175 AP — so I now add 10 watts to my target and I usually end up within a few watts of where I want to be.
One factor you need to keep in mind is that the amount of climbing and the steepness of the up-slope compared to the down slope. The reason being that EN execution has us aiming higher than our target AP going up and coming off the gas a bit when going down, but if you are just coasting (because you are going over 32 mph) then your AP for that down section will be close to zero. So the more you are coasting, the lower the AP for the ride will be compared to your target AP.
YMMV.

Al Truscott

@ Matt - your original question was about splitting a ride into segments, and "chasing" the average power within each segment as a proxy for trying to hold to a specific IF/NP.

This is the a strategy several ENer's have suggested, including Coach R. That is, hitting the interval button everhy 30 minutes (e.g.) while riding, and trying to keep a steady pace while trying to hit the metric you are targeting. It's what I did yesterday on a "steady state" ride. I was trying to go 80-80%. I threw out the first segment, warming up @ 71%, then did approximate 30 minute segments using downhills as a rest period. I ended up with 78, 82, 81, and 87 (mostly uphill on this last segment). If I'd not done it by intervals, by then end, I would have seen nothing but "0.785) on my screen for the last segment, and not known how hard I was working.

While I'm using a Joule with IF showing, I'm sure a steady effort level using AP and eyeballing the current (3 second averaged) watts in 20-30 minute intervals would accomplish just what you are looking for. Some of the best bikers here do not have instant IF on their screen, and use the AP as a proxy. Over time, looking at the watts while riding, and then going back and analyzing the intervals after the fact, you'll learn just what number works for you. And keeping it steady is also an art that can be learned. Even the Joule and Garmin dont give you VI - one would have to do the math on the fly using NP and AP, and I doubt many folks actually do that. I know I don't.

matthewbward

Thanks for the replies everyone, very helpful!

@Al - The strategy you're alluding to sounds exactly like what I was going for. Steady-state intervals is a great way to think about a race. The bottom line is every 30 minutes my AP should be as close to my goal NP watts as possible, taking a SWAG for the effects of the low power situations like downhills.

What would you put on your display when you're executing this strategy? I don't have the ability to show 3 second power. I only have instant power (captured every 1 second) or my lap average.

Dino Sarti

Interesting question that may be off topic. I am using a Garmin 500 and it will display "Percent of FTP". I use this a little more than looking at the watts because then I ma not doing any math. "Percentage of FTP" = IF, correct?

matthewbward

BTW, I just realized the LYC can display 3 second power averaging even while recording at 5 seconds, according the online manual. I had no idea. I'll try that tonight.

Gene

 @ Dino. You are right %FTP is the instantaneous IF. The problem I've found is that it jumps, I can't figure out a way to make it a3 second average. I display both 3 sec avg and %FTP. 

[Deleted User]

Posted By Dino Sarti on 23 Apr 2012 03:44 PM

Interesting question that may be off topic. I am using a Garmin 500 and it will display "Percent of FTP". I use this a little more than looking at the watts because then I ma not doing any math. "Percentage of FTP" = IF, correct?

Kind of. You can use FTP% loosely as "instantaneous IF", but the way IF is defined makes it difficult to give it an instantaneous value. IF= NP/FTP. Norm power is calculated in intervals longer than 30 sec (that is, you can't define a NP for any interval < 30 sec) to account for all the spikes and jumps in power, so really IF can only be defined for an interval, as opposed to an instantaneous value. You can use % of FTP to *estimate* the resultant IF after some interval, as long as you ride very steady. Basically, you want your NP to match your average power as closely as possible to get a good IF estimate using the % of FTP.

Hope that makes sense.

Peter Greagg

I think AP is a rolling 30 sec average that weights higher power more than lower power. The point being, as Anson says, AP by definition can't be for a time period of less than 30 secs.

cgres123

@ Matthew, when you say AVG power on the LYC do you keep the LYC on AVG Watts or let it display watts every few seconds ?
If you display watts and It jumps around a lot your looking at what we all are looking at. I find that if I aim for the middle of the jump
that is about my true wattage. LYC displays between 180 and 200 I'm at 190 or so.

Something else you may find helpful is to go to your Power Agent software if you use this , it's free, program your LYC to display
power averaging every 2 - 30 seconds what ever you find more comfortable.

tuckerm

Posted By Peter Greagg on 24 Apr 2012 04:18 AM

I think AP is a rolling 30 sec average that weights higher power more than lower power. The point being, as Anson says, AP by definition can't be for a time period of less than 30 secs.

I think you mean NP no? AP is by definition average power for a given duration with everything included, even zeroes. Normalized Power is a construct to give us a supposedly better way to measure the physical costs of a ride. 

Live found that on my Edge 500 that if I exclude zeroes from my AP the number is fairly close to NP

matthewbward

@David - There are two things here. First, the current wattage which it seems like you can configure to display 2/3/5/10/30 second moving averages. Then the average wattage that is the mean over the current lap/ride. My original question was about creating a strategy to track average watts. The smoothing discussion viz. the current watts just kind of popped up. For me, monitoring the avg power every 10 minutes or so during 30 min splits while defaulting to watching my current power (no smoothing) is probably the best strategy. On the bottom line on the display, I show the split time.

rbogle

 Matt, it looks like the LYC can be set so that Av Power can exclude zeros, that may get you closer to NP estimate over intervals too...its a few menus down in the setup routine

Peter Greagg

Sorry yes Tucker of course NP is what I meant to write — my bad