20 Minute Max Power Compared To Ftp?

Hey all,
I did a search for this but didn't find anything although I thought I have seen stuff in the past. Anyway, I am entering a short hill climb(3.5 miles) in a couple of weeks. I am guessing that it will be around 20-25 minutes in duration. My question is based on a given ftp, what power should I be able to maintain for this duration? I will probably do a physical test, but I thought there may be a calculation of some kind? Thanks in advance for any help

Read this piece and you'll understand why there's no one size fits all answer to your question: http://velo-fit.com/articles/critical-power.pdf

You could plug some best efforts from your MMP chart into the free spreadsheet linked on that site and get a pretty good estimate of what power to target for 20-25 minutes. The estimate will be better if those peak power numbers were recent, represent best efforts for the various durations and hopefully weren't all recorded during the same ride.

If you've got a bit of time before your race you could do a few short time trials in the 3 to 30 minute range and plug the results into that same spreadsheet. Of course you could also do a trial run on the course or for the same duration and see what that tells you.

-Dave

If I were in your shoes, I'd just target FTP for the first 15m and gradually crank it up from there according to feel. IME, my 20m power is only 3 to 6% above FTP, a difference which can easily be eaten up by day-to-day fluctuation, good v. bad warmup, nutrition, variable nature of the course, etc.

I can usually put out about 5% more power on a 20 min effort,which is about 15 watts for a weakling like me

Thanks Dave for the usual helpful info. Unfortunately i don't have excel on my home computer. I will have to wait until i get to work on monday to check that spreadsheet out. I think I will try to do some short TT efforts just to see what I can do. The course is out of the way somewhat but maybe I'll try that too. It would be the most obvious way to figure this out!
thanks again.
-john

yeah, i would guess that small of a margin could change with too little sleep or whatever. I like your strategy though. I think i will have a tendency to blow up early if i don't watch it. good advice. thanks.

5% sounds like a good number to shoot for. I think the power thing can be very relative. I'm a bigger guy with I guess ok power. I really feel like a weakling when little tiny guys fly past me up well,any hill thanks for the advice!

If you can I would ride the climb before or find one similar. I did a local 3.3 mile climb the other day. My FTP is 325 right now and I averaged 367 for 17:35. I know it is not 20 minutes but it is a close example of your question.

yeah, thanks for the reply! I was kind of hoping for similar results. I guess I will just have to do a practice run to see what I'm capable of. Generally when I do my usual 20 minute hill climb I am already a little tired from other shorter efforts along the way. I will try it fresh and see what happens.