Power measurement

hobbescp

question.

As far as I'm aware there are three factors which dictate my ability to climb Pyrenees mountains..(i) my weight, (ii) bike weight and (iii) power (wattage).

I can monitor the first two easily enough but I was wondering how I can measure my power without the use of the fancy crank measuring system that the pros use... i.e. is there a simple distance / time / max effort formula that I can apply to calculate this? Also if there is such a formula, then can it account for fluctuations in weight over time (as I expect to lose weight over the next six months)?

Any help for the clueless would be appreciated.

Thanks
Hobbes

ut_och_cykla

You can get a braod picture by using Kreuzotter.de or similar but you need a fair bit of info to plug in. I used it to train for and predict a 'doable' time and speed for alpe D'Huez. You can play with weight of bike, rider etc and surprise surprise for the very slow somewhat chubby a few kilos here or there make some but not great difference.I 've just got used to teh idea that I'm a weak, oldish girly

dennisn

Knowing what your power output is will not have any effect on your climbing
ability. Doing the work required to make yourself stronger will. And yes, your
weight and your bikes weight do make a difference, to a point . Mostly climbing
deals with how strong you are. Like many things good climbing can not be bought,
only worked at.


Dennis Noward

pedylan

ut_och_cykla wrote:

You can get a braod picture by using Kreuzotter.de or similar but you need a fair bit of info to plug in. I used it to train for and predict a 'doable' time and speed for alpe D'Huez. You can play with weight of bike, rider etc and surprise surprise for the very slow somewhat chubby a few kilos here or there make some but not great difference.I 've just got used to teh idea that I'm a weak, oldish girly

Me too - but I'm actually a middle aged bloke.


.

Zendog1

My physics is a bit rusty but I think this would work.

The energy you need to climb a hill (ignoring air resistance, bike bearing friction and rolling resistance) is
E= m*g*h (m= mass of you and the bike, g = gravitational constant, h = height of hill)
Power is energy per unit time = m*g*h/t (t = time to climb hill)

So if you choose a sample hill (preferably reasonably steep and in low wind conditions) and time how long it takes to climb going full bore measure hill height and you plus bike weight can then calculate power. Repeat any time you want to monitor power changes.

DaveyL

Or alternatively, go here:

http://www.analyticcycling.com/

Or here:

http://www.kreuzotter.de/english/espeed.htm

One of the RST boys will hopefully be along soon to say which one is best, as there is a difference between the two and I can't remember which one is most accurate.

DaveyL

oops, shoulda read a bit further up the thread first!

Alex_Simmons/RST

The analyticcycling site is much better, the other uses a few too many assumptions.

But a good estimate of power can be made from a well sheltered (from wind) climb of more than a few minutes and a gradient >5% say - all you need is length of climb, time taken and average gradient.

Use it to guage improvement. The faster you climb, the better your power to weight ratio.

Zendog1

Alex_Simmons/RST wrote:

But a good estimate of power can be made from a well sheltered (from wind) climb of more than a few minutes and a gradient >5% say - all you need is length of climb, time taken and average gradient.

Wrong: The OP is looking to reduce weight and that needs to be included in calculations of power improvement.

ut_och_cykla

http://www.etape.org.uk/ has a page (under 2007 MArch?) with rough guidelines based on conversions between speed on flat and watts, hills etc. It was there I realised Alpe D'huez would be doable for me(slowly of course!).
Feed in what you know to the calculation site of your choice, and then do the same calculation at e.g 5kg less rider weight. Its not exact of course but will give you guidelines!
Training to improve your power output will also help but the weight loss needs to be slow and steady or you will likely run out of energy to keep training hard.

hobbescp

Thanks for the responses, very much appreciated. I'll use those online resources and I'll have a crack at the amateur physics too - to compare results.

In essence my concern is that I lose lots of weight but predominantly in muscle mass so it would be great to be able to monitor my power as the weight comes off.

I'm planning to get a jump start on the new year by putting in some serious climbing miles over the xmas break.

Alex_Simmons/RST

Zendog1 wrote:

Alex_Simmons/RST wrote:

But a good estimate of power can be made from a well sheltered (from wind) climb of more than a few minutes and a gradient >5% say - all you need is length of climb, time taken and average gradient.

Wrong: The OP is looking to reduce weight and that needs to be included in calculations of power improvement.

Well that's pretty obvious when calculating power up a climb. :roll:

At the end of the day, under benign conditions, if he can climb faster then his power to weight ratio has improved.

Cajun

This may be of some help:
http://www.insideride.com/media/Support ... erCalc.xls