# Climbing weight loss calculator



## SwiftSolo (Jun 7, 2008)

Help!
I can't find my link to the calculator that deals with weight loss and climbing time variables. It seems to me that you input the grade, the distance, your current weight and current best time. You could then see your calculated time at a different weight. Anyone know where to find it?


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## richardmm (Dec 23, 2005)

google query


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## Guest (Dec 3, 2009)

http://www.analyticcycling.com/ForcesLessWeight_Page.html


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## SwiftSolo (Jun 7, 2008)

kytyree said:


> http://www.analyticcycling.com/ForcesLessWeight_Page.html


That's the one. Thanks again. Your help on the chainrings was also much appreciated.


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## Guest (Dec 3, 2009)

No problem, my bookmarks run deep.


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## pretender (Sep 18, 2007)

target time = current best time x (target weight + bike weight) / (current weight + bike weight)


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## Kerry Irons (Feb 25, 2002)

*Not quite*



pretender said:


> target time = current best time x (target weight + bike weight) / (current weight + bike weight)


Unless you're going quite slowly, aero drag still enters the equation, so it's not just a matter of ratios. Plus, this assumes that power output remains constant; something everybody hopes for but doesn't always achieve


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## muscleendurance (Jan 11, 2009)

richardmm said:


> google query


WOW you waited nearly 5 years to say that, see you in 2015 :thumbsup:


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## pretender (Sep 18, 2007)

Kerry Irons said:


> Unless you're going quite slowly, aero drag still enters the equation, so it's not just a matter of ratios. Plus, this assumes that power output remains constant; something everybody hopes for but doesn't always achieve


For a reasonably steep climb I think it's a very good approximation. In that setting, the vast majority of work is performed against gravity. The estimate doesn't need power output to be constant, either, just that the grade remain steep enough that air resistance is low compared with work performed against gravity.


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## jlandry (Jan 12, 2007)

muscleendurance said:


> WOW you waited nearly 5 years to say that, see you in 2015 :thumbsup:


Holy sh!t. Thats hillarious. Good eye.


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## eddya (Aug 7, 2009)

*Another formula*

Another cute little formula (which is just Newton's gravitational potential energy formula in disguise), given a riders weight in full kit, *W*, and the bike's weight, *B*, the total height climbed, *H*, and the time it took you in seconds, *T*, the power (in Watts) required over the duration of the climb is approximated by

*((W+B)*9.81*H)*1.1 / T* .

So, you can tweak *W* and *B* and see how it affects your power. It's reasonably accurate for longer climbs, i.e. climbs where the average speed is relatively low and so aerodynamic drag is assumed to be (near) negligible.

For example, it says that a rider weighing 70 kg with a 9 kg bike will put out about 255 Watts to climb Alpe d'Huez (1071m elevation) in exactly 1 hour.


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## Fixed (May 12, 2005)

*careful*

I used to obsess about these formulas, and would calculate how much faster I'd be installing titanium and aluminum bolts on my bike. Despite getting a bike down to about 12.5 pounds, it never seemed to make that much difference. 

While a clean power/weight calculation seems so clean and objective, it doesn't seem to fit reality very well. There are so many variables, from what you ate for breakfast to air temperature to tire pressure, etc. 

Also, I have found that when I have lost a lot of body weight (fat), it usually coincides with a lot of hard training. Therefore, it's difficult to isolate which factor caused what. On top of that, I've found that when I lose weight, I also am more energized about training and racing, more confident, and then train and race more. Lots of psychological factors. On the other hand, riding a weight weenie bike sort of gives a false confidence, which typically leads to worse results. 

Bottom line, losing a significant amount of body weight, like at least 10 pounds, can make you a faster climber, but it's very hard to plug it into an equation and get realistic results.


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