Friday, November 30, 2007

So What's The Big Deal About Losing A Pound Or Two?

I saw that my friend, Dennis Pederson, created a recent blog entry about his cycling goals for 2008 (you can read all about it right here).

He mentioned that one of his goals was to increase his FTP (Functional Threshold Power) from his estimated 265 watts to 276 watts - and was wondering if that would allow him to break 19 minutes on the benchmark climb of the Bay Area, Old La Honda (OLH). His PB on OLH is currently 19:50, even though I suspect he could actually do that climb a little faster right now (that's a challenge for you, Dennis!).

So, I did some calculations of my own, and sent him a little note about it:

You said you believe your FTP power is 265 watts - that might be correct, but using your 19:50 time on OLH, I came up with this value: 260.6 watts (I'll explain how shortly).

You were wondering if raising your FTP to 276 watts would allow you to break 19 minutes on OLH. Raising your FTP from 265 watts to 276 watts is about 5%.

If we use *my* value of 260.6 watts, and increase it by 5%, which is another 13.0 watts, we get about 273.6 watts. And by my calculations, an FTP of 273.6 watts on OLH would translate to a time of 1133 seconds (18:53), or almost one minute faster, which would allow you to reach your goal of getting under 19 minutes.

So there!

Oh, how did I come up with my numbers? Simple - I use a very cool webpage, that I think I told you about before - or, if not, here it is:

http://www.chuck-wright.com/calculators/watts.html

If you plug in your weight of 172 (152 for you, and 20 for your bike and accessories) - in the Mechanical box, and plug in 1330 feet (the rise in elevation of OLH), then put in 1190 (19:50 for your PB on OLH) for the Time in seconds, you see the calculated power is 260.6 watts - now, start plugging in lower numbers for the time - when you get to 1133 (or a time of 18:53), you will see the calculated power is 273.7 watts, which is the 5% gain you were wondering about.


After sending him the above e-mail, I then thought about the fact that he had mentioned in his blog entry that he would also like to lose about 5 pounds, to get from his current weight of 152 pounds to just 147 pounds (I can only dream about getting to a weight like that!) - so I decided to do some additional calculations to figure out what losing just 5 pounds might do to his time on OLH - and I sent him this note:

Oh, I forgot to add this tidbit:

If you reduce your weight by just 5 pounds, so the total weight going up OLH is 167 instead of 172 (you + bike), then for that same power of 273.7 watts, your time drops to just 1100 seconds, which is a time of 18:20 - and now you're just 20 seconds from breaking 18 minutes! If you can drop 8 pounds, and get it to just 164 pounds for the total weight, you now hit the magic time of 18:00 exactly!

If ever there was a reason to drop 8 pounds, that would be it!


So is losing a pound or two going to make any difference in how fast you climb a mountain?

You bet!

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