squatchy

Hi

I'm good with math but I just don't know the equation. I wan't to know what gain I will make with power/weight ratio. I'm a big guy. I'm 6'3" and I weight 250 lbs. I don't know what my power number would be as I don't own a power meter just yet. I am very strong. Any way Can some one tell me what I would gain in power/weight if my power stayed the same as it is now and I lost 10, and then again 20 lbs. I suppose we have to fake the power number , but I imagine you guys with meters might be able to guess some what accordingly.

Can you tell me the math gains and then maybe surmise what that would feel like while actually riding. I'm having a hard time slimming down even though my fitness level really soared this past year and I need some motivation.

Thanks for your help

Ryan

clemsongirl 

The link is to a calculator that you can play with to see different p/w ratios with your weight loss numbers. The site has other pages about p/w. You'll need an estimate of you watts and you need to get that real number anyway to really know. Think about the muscle mass loss that can come with weight loss. Benefits should be better climbing and sprints.

https://www.americanroadcycling.org/T...alculator.aspx

gregf83 

250/240 = 1.04 or 4% improvement. This will translate to a 4% improvement in speed up a steep hill
250/230 = 8.7% improvement.

howsteepisit

Power is not a single number, so I am thinking you are referring to a threshold power which is generally considered as your power output for a 1 hour time trial say 275 watts. The power to weight ratio then is Threshold power/weight in kg. 250 pounds is 113.4 KG (2.2 lb/kg). So dividing 275/113.4 = 2.43 watts/kg.

Should you lose 20 pounds we get 230lbs/2.2 = 104.3 kg and 275/104.3 = 2.64 watts /kg.

Now that you know that, what are you trying to figure out?

squatchy

Thanks for the help.

I signed for a 3 day tour comming up next June that has got me pretty scared. I ride a lot, 2000 miles last year, three centuries, (my first year) and just bought a Cyclops indoor training bike with power to get better prepaired over the winter. The tour is especially hard with tons of high altitude climbing. 240 miles in 3 days with 16,000 ft of elevational gain with many tops at over 14,000 ft. Not only am I planning or working hard I was hopeing to ge a better idea of how much loosing weight would help me. Obviously being fat is a huge detriment but I really don't know what the difference would be if I were to lose 10 or 20 lbs and still keep my strength. I was just thinking that if I knew what a difference losing weight would make I might be more inspired to do what it takes to drop some weight.

clemsongirl 

It would make a difference in your overall health, life span and enjoying bicycling with its fitness benefits. Good luck and I hope you can lose enough to enjoy the difference and make your tour easier and more enjoyable!!!!

DataJunkie

In climbing losing weight is of an even larger benefit. I could tell a difference in my climbing speed every 5 lbs I lost. However, I did drop down to 140 lbs last year and found that counter productive.

bigfred 

You'll suffer just as much. You'll just be going faster as you do.

Seriously though. 20lbs will make a pretty noticable difference in how you feel while climbing. It's great when as you put power to pedal you actually feel the bike accellerate, instead of just groaning.

I'm down about 20kg from my high point. So, obviously my change will have been somewhat dramatic. But, I'm targeting a 5-10kg loss for 2013 to help in cutting 0:30 from my target century.

It's almost always worth loosing weight in cycling. It's far easier than increasing your strength and doesn't subtract from your budgetted training time.

Looigi

A very notable anti-doping american cyclist is reported to have said, "It doesn't get easier. You just get faster."

Based on what you said about your riding level and experience, I would say there's absolutely nothing to be afraid of. It won't be easy, and you will have to take breaks, and maybe even walk the bike up some steep sections, but I believe you'll be able to complete it. And if not, so what? The important thing is that you tried.

DataJunkie

I started riding somewhere around 210 or so. You can do it. Just take your time

ericm979

True, but when you get faster on climbs you won't be pushing as hard to keep up with other people or to simply make it up a long or steep climb. So you can back off on the suffering then.

When I was fatter and unfit I was hurting on every climb. Now I can go for what most people consider a very difficult climbing ride and go fairly easy.

squatchy

So Eric. How much weight did you lose? Do you think the biggest difference was your weight loss or did you get in better shape?

ericm979

I lost about 35 lbs, down to 145 +-. It took a few years; I was more interested in getting fit than losing weight. I've gotten fitter but no lighter since; at the peak of race season I'm about as light as I can be. If you measure from when I started riding to when I hit 145 lbs, fitness and weight loss were probably about equal for improving my climbing. If you measure to now it'd be fitness for sure. But I've had 12 years of training.

https://analyticcycling.com/ -> static forces -> less weight on hill is a good model for figuring out how much faster you'd be with less weight.

mr_pedro

I dont think anybody can tell you your power based on just what you write.
I like to use the calculator from this site: https://bikecalculator.com/
What you can do for a very crude estimation is measure the average speed you can maintain on a flat road with no wind for a duration of e.g. 20 minutes. Then plug in your numbers in the calculator and get the power you can maintain for a long period of time, like on a long climb.

Using that same power number you can now start changing the grade and check if the speed is acceptable. You can then lower your weight and check the speed gain, for big hills the % weight drop matches the % speed gain.

Carbonfiberboy 

It's even simpler if you measure your vertical feet per hour and distance covered on a long, steep hill, so aerodynamics don't much enter into it. You'll need to know your weight, clothed, and the weight of your bike and bottles during the trial. Here are a couple more calculators:
https://www.hembrow.eu/personal/kreuzotter/espeed.htm
https://www.machinehead-software.co.u...alculator.html

It's reasonably accurate, enough for comparison purposes.

mr_pedro

Just that A 20 minute hill where wheel drag and air resistance don't matter might be hard to find and also no fun to climb .
On the flats you also need to estimate wheel drag and air resistance, but that's what we have the calculators for.

gregf83 

You need more than a calculator to estimate wind drag. Not many people carry around equipment to measure wind speed.
A 6-7% long hill is good and wind resistance will be minimal.

mr_pedro

Ok, so the question is how to best estimate FTP without a power meter. I agree a 20 minute hill would be most accurate as it leaves wind and tire drag out of the equation, even if it is not very steep it would still be more accurate as wind would play a smaller roll than on the flats. It does require however the capability to measure the incline, how does it work with a variable incline, does a constant vertical speed amount to more or less constant power output?