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Body weight - biking question?(12 posts)

Body weight - biking question?ALr
Mar 1, 2002 3:56 PM
How much extra energy does it take to going uphill if a prson is 2 lbs as compared to a 170 person of the same height.Have there been any scientific studies done?
re: Body weight - biking question?No study is needed
Mar 1, 2002 4:10 PM
It's pretty much basic physics. Gravity is constant. Any climb has a certain angle relative fo flat, or vector. All you really need to know is how much the biker and his bike weigh combined and the coeficient of friction betwen the road and the bikes tires. Then its just a matter of calculating how much energy would be required to move that object a certain distance along th vector assuming you ignore any effects of the wind.
But there HAS been at least one studycory
Mar 1, 2002 4:23 PM
The physics are obvious (well, not to me, but to people who understand physics). What I CAN tell you is that the difference from a significant weight loss is astonishing. I lost about 40 pounds last year (you think gaining 2 pounds a year is no big deal until you realize you've done it 20 years in a row), and I set personal records on every climb I do. I can go up and down a seven-mile steady mountain bike climb near my house in less time than it used to take me just to go up it.
Somebody, possibly Chester Kyle, computed the difference in times from small changes in body weight, aero drag and I think one other factor maybe 10 years ago, in both a 25-mile time trial and a specific climb. I don't remember the details, but it seems to me he even considered the effects of friction in the derailleur pullies, stuff like that. I can't find the copy I saved, but at least in theory, a weight loss of just two to four pounds was detectable. You might search under Kyle's name to see if it turns up.
But there HAS been at least one studyNo study is needed
Mar 1, 2002 4:26 PM
Well its definitely more than theory. Climbing a long distance with 2 lbs less will definitely result in much less relative energu needed to climb at the same rate or a significantly faster speed assuming the same energy is input. If you can find that study I'd love to see it.
Now we're talking!Kerry Irons
Mar 1, 2002 4:55 PM
a 40 lb weight difference (210 lb. vs 170 lb.) means a 20% increase in effort on a 6% grade. Losing this kind of weight makes a huge difference. That's over a 1 mph difference for that 40 lb (6% climb, same effort as required to go 20 mph on the flats for the 170 lb rider).
Pardon the bad joke........Len J
Mar 1, 2002 5:18 PM
but it reminds me of the old Rodney Dangerfield line:

Wanna lose 40 lbs of ugly fat?

Cut off yer head.

Len
Need more basis data.Kerry Irons
Mar 1, 2002 4:32 PM
How fast is the rider going? How steep is the hill? You need to have a basis before you can ask a question like this. If you assume a 6% grade, and the same level of effort it takes for this rider to go 20 mph on the flats, the extra 2 lb requires 0.6% additional effort - about 5 calories per hour out of a total of about 625 calories per hour. Speed is slightly less than 7 mph. When climbing, height makes no real difference, since aerodynamics is negligible. Unless height difference is extreme, it doesn't count for much on the flats either, since the rider is bent over at the waist.
you can calculate itRrich
Mar 1, 2002 4:38 PM
at the ANALytic cycling website
re: Body weight - biking question?Boris
Mar 1, 2002 6:29 PM
All the other people who posted a reply to this question basically said the same thing: yes, losing weight makes a big difference.

What these people forgot to mention is that it is VERY hard to conserve the same amount of muscle mass in your legs when you are losing weight. Obviously, the heavier you are, the more muscle mass you have in your legs; as you lose weight, all of these "equations" and "studies" would work... if only the rider was just as strong when he is however many pounds lighter.

Just something I thought I'd mention....
Example from: " 29 Pro Cycling Tips for Roadies"bent_spoke
Mar 1, 2002 7:37 PM
"According to exercise phsiologist David Swain, PhD, if a 165 pound rider loses 10 pounds while maintaining the same power output, he'll save a whopping 2 minutes on a 5-mile climb."
weight lossPeter E
Mar 2, 2002 12:52 AM
im a bit interested in if you can try so hard to loose weight that your starting to loose performance because your body gets weak.
if yoor powers will run out if you go down to much?
weight lossstella
Mar 2, 2002 10:48 PM
muscle loss and weakness are, of course, very important. my advice is to use the 30-30-40 diet. read about it in barry sears book, THE ZONE. if followed carefully you will not only lose weight, but gain strenght and muscle mass. i say this from personal experience. using again for this training season and let me tell you, the weight is falling off and i feel fantastic. btw, a new study on sports drinks and performance in one of the bike rags points to the need to include protein in sports drinks. good luck.