Normalised power in a road race

Bronzie

Right then, still having lots of fun collecting lovely data with this PowerTappy thing.

From a Cat 3/4 race I did on Sunday, my normalised power for the first 1h03m (26 miles) was 290W (average 205W). My understanding of NP is that this is the physiological equivalent of riding at a steady 290W for this duration.

1) How accurate is the NP algorithm in real terms? Does it correlate really well between stop-start race efforts and steady state?

2) Assuming the race continued at a similar pace* to the end (56 miles c.2.5 hours), what ballpark figure for FTP would I need to be able to achieve to ride the full 2.5 hours at NP of 290W?

* - in reality things probably calmed down a bit towards the end as riders got more fatigued

chrisw12

I've seen posts on other forums questioning the validity of Np. I certainly dont have enough knowledge to judge.

For what it's worth my mate has a powertap and he'll often tell me his np rather than his true average simply because it's higher.

What I've noticed is that when he does a tt, np=ave power
Where as on our hilly rides there's a difference BUT now where near as much as you had.

I'm stating the obvious above as the maths of the formulas fit those statements.

The big difference between your np and ap suggests a great amount of variability in your power. What that means I dunno. I'm sure Alex will help out there.

Alex_Simmons/RST

Bronzie wrote:

From a Cat 3/4 race I did on Sunday, my normalised power for the first 1h03m (26 miles) was 290W (average 205W). My understanding of NP is that this is the physiological equivalent of riding at a steady 290W for this duration.

1) How accurate is the NP algorithm in real terms? Does it correlate really well between stop-start race efforts and steady state?

Well the algorithm is accurate, since, well, it is precisely defined and if you are using WKO+ then it is being accurately calculated.

NP from a hard 1 hour race like effort will typically be no more than 5% of your functional threshold power. There are examples of when it exceeds that but it is rare. Over many thousands of power meter files I have for myself and many I've coached, I have seen one example of where NP possibly over estimated steady state power ability by more than 5%.

Bronzie wrote:

2) Assuming the race continued at a similar pace* to the end (56 miles c.2.5 hours), what ballpark figure for FTP would I need to be able to achieve to ride the full 2.5 hours at NP of 290W?

* - in reality things probably calmed down a bit towards the end as riders got more fatigued

Well on the assumption that you could attain an NP of ~290W for 2.5 hrs, then as a rough guage I would say your FTP would need to be about 7-10% higher than that.

Bronzie

chrisw12 wrote:

The big difference between your np and ap suggests a great amount of variability in your power. What that means I dunno.

It means I was riding a road race - spent 15 mins in the first hour freewheeling, which was nicely balanced by chewing bar tape for most of the other 45 mins. Specifically, there were 2 climbs on the circuit of around 35-50m that I had to make big efforts on to stay in contact.

Alex_Simmons/RST wrote:

NP from a hard 1 hour race like effort will typically be no more than 5% of your functional threshold power.

Hi Alex, yes I confirm I'm analysing with WKO+.

Well, obviously I found it hard, although in fact I didn't get dropped this time, rather I got held up for a few seconds by a crash and couldn't get back on. I suspect I was approaching my limit though as I was starting to feel the legs going on the climbs.
In the last race of similar distance a couple of weeks ago, I lasted around 1h40m before I blew (this was before I got the PM so no power data available).

I'm still trying to pin my FTP down - I don't think I could do an hour at 290W. Think I'll try doing some 2x20's at around this level and see how I find them.

Alex_Simmons/RST wrote:

Well on the assumption that you could attain an NP of ~290W for 2.5 hrs, then as a rough guage I would say your FTP would need to be about 7-10% higher than that.

So around 320W then. Although I have a sneaky suspicion that I'm nearly at my limit, I presume the best use of my training time now is to focus on improving FTP as much as possible?

Either that or I learn how to be a lot more economical during races.

Perhaps what the TruthMeter is really telling me is that I should just take up chess? :oops:

Alex_Simmons/RST

Bronzie wrote:

Alex_Simmons/RST wrote:

NP from a hard 1 hour race like effort will typically be no more than 5% of your functional threshold power.

Hi Alex, yes I confirm I'm analysing with WKO+.

Well, obviously I found it hard, although in fact I didn't get dropped this time, rather I got held up for a few seconds by a crash and couldn't get back on. I suspect I was approaching my limit though as I was starting to feel the legs going on the climbs.
In the last race of similar distance a couple of weeks ago, I lasted around 1h40m before I blew (this was before I got the PM so no power data available).

I'm still trying to pin my FTP down - I don't think I could do an hour at 290W. Think I'll try doing some 2x20's at around this level and see how I find them.

Sorry, it wasn't obvious because you didn't say you got dropped.

Given the 5% margin of error in a hard 1hr NP = FTP, then your FTP could be anywhere from 275+ W.

Bronzie wrote:

Alex_Simmons/RST wrote:

Well on the assumption that you could attain an NP of ~290W for 2.5 hrs, then as a rough guage I would say your FTP would need to be about 7-10% higher than that.

So around 320W then. Although I have a sneaky suspicion that I'm nearly at my limit, I presume the best use of my training time now is to focus on improving FTP as much as possible?

Either that or I learn how to be a lot more economical during races.

Perhaps what the TruthMeter is really telling me is that I should just take up chess? :oops:

A focus on improving threshold is fundamental. How best to achieve that is the trick.

The truth meter is just telling you where you are at. Now you need to work out how to bridge the gap to where you need to be.

Bronzie

Alex_Simmons/RST wrote:

Sorry, it wasn't obvious because you didn't say you got dropped.

I was practicing improving my economy (of the truth)