How to choose target power for various cycling durations
Hi team! I am doing a ~46 mile multi-surface cycling time trial this week for charity (gravel, pavement and some crushed limestone). It has ~2200 feet of climbing according to the strava segment. Unlike a normal bike race, this must be done solo, so a target power become more critical without other riders to try and hang with.
I would like to target ~2hr15min (maybe a little faster and possibly as slow as 2hr30), but more importantly, I'd like to see the max power I could average for ~2hr15 minutes (as a % of my FTP or % of my 1 hour power. My last 1 hour power record was 354 watts in the aero bars outside and I've done a LOT of cycling since then. But I am also weighing ~91 kg.). If I can push a really strong effort, I won't care too much what the time ends up being (I probably can't win it anyway, as the current leader is ~2:09 moving time, ~2:11 total time. I have competed against him in at least 5 other weekly challenges recently and I know his w/kg is significantly better than mine and he consistently beats me by a solid margin (although he does tend to do worse on the gravel than the pavement). We are required to stop and get a selfie on course at a designated spot, hence the 2 minute stop).
I asked about this specific case in group me. But a better discussion would probably be general strategies/tools for how to take your various power records and scale them to other durations (for example, 120% of FTP is generally a good target for a 5 minute all out effort). I'm sure WKO4 can do this, but I don't have that yet. Can Training Peaks or Final surge? I have heard of best bike split and it sounds like that can make some recommendations along these lines, but I'm not sure that can account for gravel and soft surface riding.
Also, should I use average power or NP as my target? If I had to guess, I would probably go for ~90% of FTP, and yes, I expect that to be very difficult, but I did take it a little easy the last ~1.5 weeks. @Tim Sullivan suggested that 0.9 might be a tad high. I wouldn't be surprised if that is the consensus. There are also a lot of hills in the last 10 miles (mostly pavement). So maybe start w/ 0.8-0.85 and see if can push it up on those final hills?
Thanks a ton!
Comments
Let's start with the PD and MMP curves! What does the model think you can hold for power for about 2:15? (PDC). What have you actually done for that duration in the last 90 days (MMP)
thanks @Tom Glynn ! I do not have WKO4 or 5. Can I make those graphs without it? I do pay for training peaks and Strava premium.
and I should add, that unless I racing in Zwift, going for a KOM or doing an interval I ride really easy. So I am sure I have almost no data on what i can do if I really pushed for 2.25 hours. Most Zwift races are 1 hour or less. I do go all out for 1 hour semi regularly as FTP check.
It's time to start pushing harder for longer :)
TrainingPeaks has a graph called Peak Power Bike that may help. If you don't have much reliable data passed an hour or so, but good data below that (I assume if you are pushing hard on Zwift then the 20-60 minute stuff is pretty good), then use the Zwift data to estimate FTP. Look at some Half IM files if you have done one and see IF numbers. That may get you in the range. My max power drops about 10% from 1 hour to 2 hours.
I agree with @Tom Glynn looking at your best for 2 hours will give you an ballpark idea depending on your 2+ hour race or maximal efforts. Strava or Training Peaks can give you that chart.
It could be interesting to think of not only the watts you need, but what energy system and source (fats vs glycogen) you are using to generate those watts. For easy efforts we tend to use fats for fuel. For harder efforts above FTP are primarily stored or immediately available glycogen. For sub-threshold efforts you are at the edge of your maximium lacate steady state - producing and clearing lactate. But every time you go over FTP you are going to generate more lacate than you can clear, also reducing your future available energy.
Each of those efforts above FTP will draw from your glycogen stores, but you won't get the most bang for your energy buck because above threshold you will be producing more energy anaerobically. I would think that the high VI will have a higher energy "cost" and most likely impact your ability to generate sustained power after the 1 hr mark.
The VI for your approach will be ridiculous for a 0.9 IF. There are 3 long descents that will most likely drop your IF average. Say you could ride downhill at IF .8 for 10', that means you would need to ride IF 1.1 (389 W) for 10' to average IF 0.9 for those 20'. Those punchy climbs efforts will put you over FTP repeated and every time you do that there is a cost in energy efficiency. It will be essentially a 2 hour interval session or like crit city for 2 hours. That might be the most inefficient way to race.
It could try and see what happens. If you do attempt it, it would interesting to see your IF and VI for under 1 hour and after 1 hour. The 3 steepest climbs are 20 miles into back the course.
My take on the fastest possible time on this course would be to:
- Do your analysis if terrain and wind like you normally do.
-Use your advantages strategically - push the watts downhill (within safety of course).
-Don't press into the wind. Press with the wind. Press on the flats.
-Climb above your threshold only on the steepest portions for the shortest durations.
-Use a 4 month window for your peak power chart. Use that power number as a starting point.
-Divide the course into two parts.
First 20 miles rolling. Use your peak power for 2 hours as a guide for the first hour of the ride. Try to keep your average and NP close for the first 20 miles. Use the numbers as a rein.
-Last 25 miles 3 steep climbs. Race. Increase effort. Go by feel and push the numbers. Using the thoughts above.
-At the 40 mile mark after the last climb you are 5 miles out. 15-25' depending on the surface. At this point you are all in. Use the numbers if that motivates you, otherwise it is all about effort.
-Fuel early and consistently to setup the second half race. The first hour sets up the race second hour. You need to be able process calories while close to your limit. So, easily digestable is key.
@Larry Peters
Ok, thanks a ton. I’ll check that out @Tom Glynn !
Woah, @matt limbert , I love it! I am taken aback and so grateful for your careful and thorough reply! Based on a lot of “racing” (solo Strava TT efforts organized by local race director) I’ve been doing Over the last 6 weeks at 1-5 minute segments up through 20-40k efforts (all 1 hour or less), I was finding that it was faster to push harder uphills and rest more on the downhills. I was surprised because this seemed counter to the EN dogma of “flattening the hills” and evenly distributing your power over the incline and decline. But I recognized and thought it made sense that the situation was different with shorter efforts. I wasn’t sure where the line was (in terms of duration of the effort) between where “flattening the hills” versus surging over hills would be more efficient. But your logic is sound to me, and I would totally believe it would be better to avoid efforts over FTP on the hills early in a race of this duration. I will read your response closely and plan to take your advice. I really appreciate it. The good news is that the final 10 miles is mostly pavement. There is one fun, winding descent in the gravel, but it has corners with poor visibility, so I’ll have to ride that descent conservatively to be safe.
I will look at my TP power chart in the morning. Thanks a million to you both!
@Larry Peters Go get 'em! Your nemesis will never know what hit him! Kinda like the scene in Top Gun "Where'd who go?" 🤣 I look forward your post race update.
Thanks again SO much for the advice and support @Tom Glynn and @matt limbert . I used your advice as much as I could and the race went really well. It wasn't a perfect execution, but overall, I'm very happy with the effort. Sadly, I was broadcasting my HR from my garmin 935 and recording event with my garmin edge 520 plus. This created interference and I had micro power drops periodically during the event. So I don't know exactly what the numbers were, but they were pretty good. I wrote a lot of details with photos from training peaks screen shots in my strava file.
No need to read it, but since you provided so much help and advice, I did want to follow-up and let you (and anyone else reading) know how it went:
Thanks!
@Larry Peters 275 watts for 2.5 hours - are you sure you had power drops?? That is a ton of power!
I looked at the Strava segments and it looks like you were pushing a lot of power in the beginning with less power at the end. Was this terrain related or a race strategy? Or just going out too fast 😂
The weather looked good too at 62 degrees, that's pretty darned good!
For nutrition, how many calories and fluids were you aiming for? Did you have a good meal plan a day or to before the race and race morning? I would think you could get by with less calories on a 2.5 hour race if you had a big meal the night before a lots of calories for breakfast.
Congrats on the race!
Thanks a ton @Tom Glynn ! When considering my power numbers, Keep in mind, I’ve been weighing 91-92 kg (morning, unclothed, fasted weight) lately. But I really appreciate the kind words!
yeah, looking at Strava segments, it sure looks like I had power drops (two screen shots in the Strava picture showing the evidence). And this is a known issue when I run my Garmin 935 and my edge 520 at the same time for recording. But I’ve never tried broadcasting heart rate for my 935 to my 520 until that day. So this is another reason i suspect micro power drops. But it may not have had a big impact on the numbers.
if you are looking at any of the segments after “the leg wrecker final sprint” segment, that was the very slow ride home my girlfriend and I took. We rode to the starting line on our bikes, did the race, and then rode home. We like to bike commute whenever possible. So I didn’t fade that much during the race.
yes, I did have a meal plan, but I deviated a little bit from it and did not take as much nutrition as I should have on the ride. So I felt like I lost a little power from lack of calories in the last 30%, but I managed to still push pretty good power.
if you look at the screenshots in the Strava file, I have a breakdown of the different portions of the race with TrainingPeaks data and explanations such as the one shown below:
This one shows NP of 288 for first 18 miles and NP of 287 for last 26 miles, so I don’t think I faded too much, even if I felt like I was dying and getting weak.
Thanks again!