Marz wrote:
:: On Jul 27, 5:25 am, "Roger Zoul" <
[email protected]> wrote:
::: Patrick Lamb wrote:
:::
::::: On Thu, 26 Jul 2007 10:46:13 -0400, "Roger Zoul"::
::::: <
[email protected]> wrote:
:::::: Joe wrote:
:::
:::::::: I've been dieting and I'm curious to see how many calories
:::::::: riding my bike an hour per day through a wooded trail burns. I
:::::::: bike at a moderate pace between 10-15 mph and if I do a
:::::::: calculation on this site I get numbers in the 700 range.
::::::::
::::::::
http://dftools.ivillage.com/healthtools/calc_cb.cfm
::::::::
:::::::: My wife seems to think that number is way too high since she
:::::::: says riding the exercise bike at the gym for one hour burns
:::::::: 1/2 that. I'm trying to count my calories burned per day and
:::::::: I'd really like to get an accurate number to put on my chart.
:::::::: Which would be correct?
::::::
:::::: I count 40 kcals/mile, no matter how fast I ride. 10 miles = 400
:::::: kcals. 15 miles = 600 kcals.
:::::: 20 miles = 800 kcals. Note, riding faster means you go more
:::::: miles in an hour, so that's how you burn more calories. For the
:::::: most part, though, you're doing the same about of work
:::::: regardless of speed. Hence, the energy used should really have
:::::: little (to the first order) to do with speed.
::::::
:::::: I think the numbers at the site are too high.
:::::
::::: Not really enough information. Need rider and bike weight, a good
::::: guess at cross section, and info on tire type.
:::
::: Not enough info for what? An extremely accurate answer? You're
::: never gonna get that. The 40 kcal/mile is not exact and is not
::: perfect for everyone. However, it's a lot more meaningful than the
::: numbers that come out of that website, and those that come out of
::: devices like the Polar 720i or the Edge 305, which are all way too
::: high.
:::
:::::
::::: FWIW, a few years back I started collecting formulas for cycling
::::: calories. I think I ended up with five different formulas -- not
::::: surprisingly, I got five different answers, which typically
::::: varied by
::::: up to 2.5X.
:::::
::::: Oh yeah, the difference between 10 and 15 mph matters more on the
::::: road -- the aerodynamic drag isn't significant in the gym.
:::
::: I won't argue that. But you still can't tell me exactly how many
::: calories I burn on a 10 or 15 mile road ride. Sure, drag makes a
::: difference, but it ain't that big of a difference.
::
:: Drag can make all the difference, especialy at speeds above 15mph. I
:: got this quote, " Drag from the air isn't a big problem at low
:: speeds. However, it has one unsavory characteristic: the force
:: required to overcome air drag rises as the square of the speed" from
:: here ...
http://users.frii.com/katana/biketext.html (about half way
:: down the page). That's why some online power (and hence calorie)
:: calculators ask for air temperature and altitude so air denisty can
:: be included in the calculation. e.g.
::
http://www.kreuzotter.de/english/espeed.htm
Sure....Again, I don't argue that point. But keep in mind that most people
going much above 15 mph for long with want a more aggressive position to
reduce drag to continue to go fast, thus reducing the calories expended.
Furthermore, those who don't adopt that position will probably not spend
that much time at high speeds working to overcome the force. Hence, as a
good estimate, that 40kals/mile is probably still much better than the
online calculators. At least the one used by the OP....