I got a questions, which might be of interest for all of you who are analyzing the races of the season.
Last season I did a race, which was won/lost on a specific hill. I would like to know: How do I calculate the power I need, to keep up with the group, if every componend (equipment, weather, etc.) stays the same next year.
First the hill:
The gradience is around 5 percent, which gets you an alevation gain of 72 meter on 1300m lenght.
My last year perfomance:
To finish this segment it took me 4:10 minutes and I averaged around 305 watts. Me and my bike were at maybe 81 kilo.
What I strive for:
To keep up with the group I have to finish the hill in 3:20 minutes.
Question:
How much power do I have to put out to finish the segment in that time?
How would the needed power change if I lose 2kg and me and my equipment just weight around 79kg?
If we disregard drafting, perhaps the easiest to do would be to find a strava file of someone who finished in the group and guess his his weight. Then you would have the watts/kg you need.
But they propably used a different powermeter - so i can’t compare it to my data. And guessing their weight is not an option, because it’s to inaccurate.
Plug your power and weight in, plus the distance and gradient, see what time it spits out, then maybe play around with other parameters to get closer to your actual time. Then adjust power and weight to see how time varies with everything else constant. Helps if you can do some Strava sleuthing of some people from the 3:20 group to validate the numbers.
Of course what it won’t tell you is what training everybody is doing over the winter and who is going to show up next year and do that hill in 3:10…
last season I´ve used bestbikesplit.com for my specific race. You can upload one track /gpx file for free and play a little with all different components as weight, weather and so on. May this could help you.
and yes, there is a physical formula to calculate, but it´s quiet long and you`ll need a lot of information (e.g. rolling resistance, weight, speed, wind speed, surface of bike + rider and so on and so on)
The issue is that your result is only as good as your estimates, such as drag coefficient, frontal area, coefficient of friction etc. Bikecalculator will give you ballpark figures for these and will almost certainly do a better job of calculating it than us.
Use bestbikesplit.com like @sebi1981 advised. Even free account will be suitable for your need and it gives you the best estimation about your needed power. There are all variables you need - from drag, historical weather, bike, road quality etc. You can easily play with them to find requirements you need
I have checked the accuracy with my rides from strava and it was almost spot on.
I have a similar climb on a local “throw down” ride. I’ve run the numbers on my climb so I’m familiar with the analysis!
My hill is a little bit steeper, and drafting makes a big difference at higher speeds when everyone is going full gas. I’ve seen around 15-20 less watts when tucked in on my 1.6km, 6% climb.
For you, you’ll need around 390w to stay with the front guys, assuming no drafting. You’ll be surprised that weight matters a lot less than you think on a climb this shallow and putting out high watts. I’ve calculated it around 1 second per pound saved - your climb would be similar - likely a little less than 1 second per pound.
With good drafting and pacing, you’ll probably need a minimum of 375w at the same weight.
These type of calculations really show why bigger guys have their work cut out for them. On a really fast day, I need to do my 4 minute climb around 6w/kg. I’m only 64kg, so the numbers don’t look too crazy. It’s rare to see a rider over 180 pounds in the front group for this reason - you need a whole lot of watts!
The climb is undoubtedly a Strava segment. That will give you a wealth of data by looking at the segment leader board. It will also tell you the average grade and length which you’ll need for any calculations. If you have a premium subscription, you can filter the leader board by weight. The little lightning bold next to the power number means its from an actual power meter not an estimate - only look at those numbers. You also can find the results for the climb that occurred in races to see what folks were doing after X distance in their legs. Pull up the race results for the last few years, find as many guys in your race class as you can and look at their Strava data for the race and the climb. Look for guys that placed high and find their times for the climb. That’s your target.
Hi tilofr I can help you out with this one. The maths is built into our climbing calculator. First enter your climb: 1.3km and 5.5% (=> 72m rise): then your weight: then your climb type. I retrospectively put in your FTP from a guess (dont worry about this, its not needed for this calc). And the results…
with your baseline base power is 305 (4.16w/kg) you will get 4m 10s as you said (the calc actually says 308w
To achieve 3:20s you would need a power of 399w (5.4w/kg) with 81kg
If you drop to 79kg you would need a power of 384w
Tactics will be as important (if not more) than raw power.
If you can sag the climb you might be able to get away with a 30s slower climb (field size dependent) than the fastest people if you play your cards right.
