Calculate FTP from shorter time trial

Calculate FTP from shorter time trial

Postby Aaron » Wed Jun 13, 2012 9:10 pm

I've been using the Chris Carmichael book Time Crunched Cyclist for training with power. He has you do an all out 8 min test and then base your training rides off the average power from this test. I'm wondering if anyone knows how to calculate FTP based off an 8 min test rather than a 20 min X .95 or 1 hour ride.

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Re: Calculate FTP from shorter time trial

Postby lungbuster » Thu Jun 14, 2012 6:43 am

One method is to load all power data into a program and check the power distribution chart. Time up the side v power on the bottom. Use bin size of 5 or 10 w. See if you can find a distinct drop in power after the bell curve starts it's way down. See Allen and Coggan, Training and racing with a power meter, p p44-52.
It think there is also a formula you can use but can not remember where I have seen it. I thought it was something like the 20 min test but each time you have the time you reduce the multiplication factor by .025. Don't quote me on that though. I could just be talking sh!te.
All the best.
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Re: Calculate FTP from shorter time trial

Postby Velocomp » Thu Jun 14, 2012 7:18 am

In the POWERHOUSE, we use a 5 minute, all out test to estimate FTP. In this test FTP = average watts x 0.85
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Re: Calculate FTP from shorter time trial

Postby mtenzer » Thu Jul 12, 2012 8:40 pm

Hi. I'm copying a similar post that I just put up plus some insights gained after running 2 x 8 minute "field tests" a la Carmichael and the fit test on the newton +.
I read somewhere that the multiplier for the 8 min. test was 90% to get FTP. Based on my 293 power, that came to 264 est. FTP. I ran a fit test this eve and conditions were mild but the cars whizzing by were ever present. I thought this would negatively affect thee accuracy. I think on my old Ibike pro it would have. However, as it stands the test ended with an est FTP of 270 !!! I'd say the tests were very consistant. I'm waiting for some input but I may try to simply do a fit test on thee trainer and make another comparison as I'd rather do all my evaluations with the same controlled variables.
Any input appreciated,
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