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Power meters and racing Ironman
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Tin Pot




Joined: 08 Jul 2013
Posts: 2197
Location: Bromley

PostPosted: Mon Jul 03, 2017 4:54 pm    Post subject: Power meters and racing Ironman Reply with quote

I've been over a lot of the old posts but I'm still unclear on a few items ahead of IMUK in two weeks, your thoughts would be appreciated.

Power Display
What outputs are useful on the display?

I found the simple "Power" number when racing fluctuated so much say +/-30W on what felt like a consistent output it was hard to get useful feedback.
Are average outputs better?

Target Power
Online references like Friel suggest I want an IF of around 0.67, I've done 0.65 for 4hrs45 on the turbo which left my legs feeling okay, but this is constant output.
Bolton will mean hills and coasting, staying at 0.65 going uphill is literally impossible.
Even 0.8 to 0.9 was pathetically easy effort at Exmoor 70.3 and led to my longest ever bike split.
A solid perceived effort on hills for me is about 140% FTP, which oddly doesn't feel as hard as 120% VO2 intervals indoors.

So if I want to average 0.67, is it sane to go to 140% up hunters and sheep house, light/coast the downhills, and easy/moderate effort 67% the rest?
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Tin Pot




Joined: 08 Jul 2013
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Location: Bromley

PostPosted: Mon Jul 03, 2017 5:00 pm    Post subject: Reply with quote

The Friel reference:
https://www.trainingpeaks.com/blog/how-to-cheat-by-using-a-power-meter-in-an-ironman/

Here’s a table I use to help determine what an athlete’s IF and TSS should be for an Ironman race. This was created by Rick Ashburn. If you know how to use it you can nail your Ironman bike and come off with good legs for running.

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Tin Pot




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PostPosted: Mon Jul 03, 2017 5:09 pm    Post subject: Reply with quote

At the last race i just used those in bold, Power and Cadence. On steady state rides my cadence tends to drift down, leading the power down, so I like to see I'm in the cadence range I want to be.

In italic are the values I'm considering as alternatives.

These are my Lezyne Macro GPS display options:

Distance
Speed
Avg Speed
Max Speed
Clock
Elevation
Grade
Ascent
Descent
Temperature
Calories
Heart Rate
Avg Heart Rate
Max Heart Rate
Cadence
Avg Cadence
Power
Avg Power
3s Power
10s Power

Lap Distance
Lap Speed
Lap Power
Lap Heart Rate
Lap Cadence
Lap Time
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Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
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Half Mara '16 2h04, '14 2h07
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explorerJC




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PostPosted: Mon Jul 03, 2017 5:45 pm    Post subject: Reply with quote

use the display you have been training with...

when will you be coasting?
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Tin Pot




Joined: 08 Jul 2013
Posts: 2197
Location: Bromley

PostPosted: Mon Jul 03, 2017 6:28 pm    Post subject: Reply with quote

explorerJC wrote:
use the display you have been training with...

when will you be coasting?


Why, if the power output that appears not to be useful? Am I misreading the information?

I recall the descent from sheep house has a number of twists and other people brake on, making it dangerous for me to power through. For example.

I can't imagine a race route that allows for the continuous steady power the turbo does.
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Iron '16 14h30
Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
Sprint '16 1h17, '14 1h40, '13 2h01
Half Mara '16 2h04, '14 2h07
10 Mile TT '16 00:26:30
Trail 10K '16 54:01 '13 54:46
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TriSam




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PostPosted: Mon Jul 03, 2017 7:36 pm    Post subject: Reply with quote

When I race, I have 4 displays on my screen.

Time
Distance
3s Avg Power
Normalised Power

That's all I've found I've ever needed
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stenard




Joined: 04 Sep 2013
Posts: 1242

PostPosted: Mon Jul 03, 2017 8:42 pm    Post subject: Reply with quote

I have a lot more than TriSam, but 3s power is my main metric. Smoothed enough to not be excessively volatile, but short enough that its represents current effort.

One thing that didn't make sense to me is that you said you were able to ride 0.8-0.9 IF and it was "pathetically easy". IF only means something if your FTP on which it is based is accurate. Your other statement about holding 140% on hills being easier than 120% on the turbo implies you may well have the issue of different FTPs indoors and outdoors. There's been quite a few posts about this on here. Can result from temperature, cooling, lack of inertia of the turbo, mental stimulation, etc.

Try using something golden cheetah. Plug all your outdoor rides into that and it will give you an estimated FTP from its power model. It sounds like you'll find that quite a bit higher. There's no point riding to power if it results in your slowest ever bike, unless that's because you then had a great at run that saved more there than you lost on the bike.
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Tin Pot




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PostPosted: Mon Jul 03, 2017 9:35 pm    Post subject: Reply with quote

Okay I'll go with 3s power, cadence and maybe distance. I'm not sure if distance helps or hinders morale.

Theres some evidence from a TT that my ftp is higher but not by much 3 or 4 %.

Ignoring that for a second how hard would you hit the hills? I would have thought 100% FTP easy to maintain for the longer hills, 120% theoretically only for the short ~2 minute efforts..? Burns "too many matches"?

I can put four VO2 intervals into my final long turbo to test I suppose.
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Iron '16 14h30
Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
Sprint '16 1h17, '14 1h40, '13 2h01
Half Mara '16 2h04, '14 2h07
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Trail 10K '16 54:01 '13 54:46
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Jorgan




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PostPosted: Tue Jul 04, 2017 8:47 am    Post subject: Reply with quote

I assume you can scroll screens, so no need to worry about leaving stuff off the main one. It's horses for courses really, but as alluded to in the last, I always use IF & NP. If my IF is drifting high, then I know to back-off ...that's where the 'coasting' downhill can be useful, especially as if you're aero you lose no time over pedalling. It's an Ironman, and not a flat course, so as an AGer, being cautious on the bike is not going to harm you when there's a marathon ahead.

You might lose 10 min by playing it safe on the bike. That's in the bank for the run. Other way around though; pushing to be on target or better on the bike might cost you 30+ min on the run.

I'm not sure who said this:
"think what can I do now, on the bike, that will help me on the run"
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r0bh




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PostPosted: Tue Jul 04, 2017 8:55 am    Post subject: Reply with quote

3s power
Lap average power with autolap every 10 (or whatever) miles.

I wouldn't go to 100% FTP on hills unless the gradient meant I had no choice, 90-95% would be my max.
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PCP




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PostPosted: Tue Jul 04, 2017 11:00 am    Post subject: Reply with quote

NP
3 sec power
Cadence
HR
IF
Distance
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tuckandgo




Joined: 03 Sep 2012
Posts: 282

PostPosted: Wed Jul 05, 2017 11:02 am    Post subject: Reply with quote

I think you are overly complicating what should be quite a simple system.

Know your expected average power for the race. (you can guesstimate this from Friels table.)

Let's say it's 200W. You want normalised power to be within 5% of this, less on a flat course, a bit of leeway on a hillier course.

BUT - AND THIS IS IMPORTANT - it is no good getting 2/3rds of the way round and saying '#@?# my average power is too high I'd better slow down' and slowing down and getting the right average power. The damage is done.

So, you want to aim for a steady 195-205W on 3sec power avg, a total cap on the steepest hills of X (pick your own number but would suggest not much over FTP.) and keep power up downhill except where impossible.

That should give you an NP of say 210W.


While you are racing don't worry about time or distance with regards to power and pacing. Just pace it and let the race come to you.
Job done.
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Tin Pot




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PostPosted: Wed Jul 05, 2017 11:51 am    Post subject: Reply with quote

tuckandgo wrote:
I think you are overly complicating what should be quite a simple system.

Know your expected average power for the race. (you can guesstimate this from Friels table.)

Let's say it's 200W. You want normalised power to be within 5% of this, less on a flat course, a bit of leeway on a hillier course.

BUT - AND THIS IS IMPORTANT - it is no good getting 2/3rds of the way round and saying '#@?# my average power is too high I'd better slow down' and slowing down and getting the right average power. The damage is done.

So, you want to aim for a steady 195-205W on 3sec power avg, a total cap on the steepest hills of X (pick your own number but would suggest not much over FTP.) and keep power up downhill except where impossible.

That should give you an NP of say 210W.


While you are racing don't worry about time or distance with regards to power and pacing. Just pace it and let the race come to you.
Job done.


This is the simplicity I'm looking for, but I've no problem with dealing with the underlying complexity to get there.

1. At an FTP of 231 multiplied by 0.67 IF I'm looking at a paltry average 155W.

2. Upto 231 uphill.

3. Display 3s Power and Cadence.


I'd love to see/laugh at the predicted bike split to haul 84kg around Bolton on 155W. In fact I wouldn't, it's just going to be demoralising.

Personally I think I'm looking at a much slower race than last year. It's not very motivational, but I've bought into the Power paradigm and I can't be sure if I'll do better or worse until the race has finished...as long as I don't die of old age out there.
_________________
Iron '16 14h30
Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
Sprint '16 1h17, '14 1h40, '13 2h01
Half Mara '16 2h04, '14 2h07
10 Mile TT '16 00:26:30
Trail 10K '16 54:01 '13 54:46
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Tin Pot




Joined: 08 Jul 2013
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PostPosted: Wed Jul 05, 2017 12:13 pm    Post subject: Reply with quote

Yep, just went on bestbikesplit - fifteen minutes slower than last year, 7hrs 13. Ugh. How depressing.

Might go for 165W, 0.75 IF. Saves half an hour, and I'm a rubbish runner anyway. Idea
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Iron '16 14h30
Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
Sprint '16 1h17, '14 1h40, '13 2h01
Half Mara '16 2h04, '14 2h07
10 Mile TT '16 00:26:30
Trail 10K '16 54:01 '13 54:46
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SGreg




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PostPosted: Wed Jul 05, 2017 12:19 pm    Post subject: Reply with quote

I think you really need to look at your outdoor FTP

You can't sustain 140% ftp uphill for long, 2/3mins max, the fact you say you can means your ftp is wrong.


I train power indoor (virtual) but race on feel because I think its best (and nothing to do with me being too tight to buy a PM...honest Wink )
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