's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

bike weight and climbing ability(12 posts)

bike weight and climbing abilityAztecs
Aug 19, 2002 9:53 AM
Could someone explain the difference (if there is one) between with a 200 lb rider climbing a hill with a 15 lb bike and a 195 lb rider climbing a hill with a 20 lb bike? Basically what is the difference between losing bike weight and losing body weight.

re: bike weight and climbing abilitybm
Aug 19, 2002 10:30 AM
don't know if i'm right, but i'll give it a try.
(This is sort of like asking for the difference between a heavy bottle in a jersey pocket versus a heavy bottle in it's frame cage)

more weight on the bike - for specific materials - may make the bike more rigid, which leads to more power.

body weight of an active person is relative to strength and power. so, maybe a bigger cyclist can grunt up a hill faster. however, the lighter cyclist may be more aerodynamic and if his/her strength is superior, may climb faster.

but the performance difference between 195lb and 200lb is a little tricky. there may be differences in muscle composition, because of genetics or talent or whatever. it depends on where majority of muscle is also. Armstrong lost 20-30 lbs upper body weight in his cancer days but retained his length strength (and even gained more)

i think that the difference in weight is insignificant for the average rider. what's more important is technique and experience and MOTIVATION.
My dependshrs
Aug 19, 2002 10:55 AM
The simple answer is none, the amount of energy expended is based on the amount of weight moved over a given distance.

Unfotunately life is rarely simple. There's too many variables in your question. If the 200lb rider has the bulk of his weight and strength in his legs and is better aerobically conditioned he will probably climb faster. If the 20lb bike is significantly stiffer than the 15lb bike it may well transfer power more efficiently and would climb faster (assuming comparable power to weight ratios for the riders in question). Another issue is where on the bikes the weight differences are found. Rotational mass is magnified and there for the weights of wheels, tires, cassettes, cranks, etc. will make a bigger difference than the the same weight say in a water bottle or on the rider.

Just some musings.

My dependsflying
Aug 19, 2002 11:16 AM
I agree it is rotational weight that matters most.
Static weight is well....static it does not have to be accelerated a thousand++ times per ride.
Everytime you slow down you need to re-accelerate the weight back up to what ever speed your climbing/cruising at.
Yes you need to accelerate both static & rotational but its the rotating weight you feel most.

As for the two riders one at 200 & the other at 195 that could mean anything. The 200 pounder may have 4% body fat & the 195 pounder may have 18% fat. In which case we know who will climb faster ;-)
go figure it out yourselfStarliner
Aug 19, 2002 11:32 AM
Try this experiment - you'll need to find a 5-lb. weight, and utilize a heart rate monitor. Go find a hill and ride up it at a certain heart rate, and time yourself from a certain point to another point. Then after a sufficient period of rest (1 day maybe) repeat the same ride procedure, this time carrying along the 5-lb. weight. Any difference should give you an idea of what answer you're looking for.
Aug 19, 2002 11:49 AM
it takes a certain amount of power to move a certain weight a certain speed up a hill. Assuming identical rider and bike capabilities than there is no difference.

But then you ask about losing body weight vs. bike weight which is an entirely different question. Assuming all the weight loss is fat and therefore shouldn't affect power output I would vote on the loss off the body. The heart will have less tissue to pump blood through, you will probably not overheat as easily, etc.
Assuming power/weight is the same, the heavy guy wins.Quack
Aug 19, 2002 12:00 PM
The 15lb. bike is only 7.5% of the body weight of the big guy. Whereas the 20lb. bike is 10%+ of the body weight of the small guy. The power/weight ratios will no longer be equal and the big guy will win at the top.

By cycling to lose body weight, you are hopefully increasing your power while also losing weight, thereby dramatically increasing your power/weight ratio. If you're overweight and opt to lighten your bike by 10lbs., you will still be a little quicker, but nowhere near as fast as if your body were 10lbs. lighter. You want to carry the most lean muscle mass in the right areas and the least fat to be an effective cyclist.
Assuming power/weight is the same, the heavy guy wins.MarvinK
Aug 21, 2002 5:56 AM
Overweight and lightening bike by 10lbs? I've ridden with some of my larger friends.... and I already think they seem to be cursed with hardware failures. I can only imagine what dropping their bike weight by 10lbs would do...

They'd certainly not be faster. Stopping for a broken spoke or other mechanical problem would put anyone at a severe disadvantage! ;)
Different riders/ different answersBreakfast
Aug 19, 2002 12:46 PM
That question is impossible to answer given that we're talking two different riders.

If, however, the 200lbs rider is riding a 15lbs bike and then loses 5lbs of body weight over a reasonable time (with no ill effect) and is given a 5lbs heavier bike to climb with then you have a good question.

My guess is that this same rider would be faster on the heavier bike up the first few climbs but eventually the extra effort in carrying the 5lbs of bike weight (assuming wheel weight was constant) would begin to make him slower than he was at the heavier body weight with the lighter bike.
Lighter guy on heavier bikePODIUMBOUNDdotCA
Aug 19, 2002 7:06 PM
Assuming both have to climb out of the saddle I'd say the lighter guy. While climbing standing you have to support your own body weight which therefore uses up energy. So the lighter guy would be more efficient on the heavier bike.

Aug 19, 2002 8:58 PM
First off what are the controls?
Do both riders output the same amount of power?
If both riders for instance output 350 watts of power at their lactate threshold then theoreticaly they would both have the same equivilant power to weight ratio(with bikes per your scenario).
Something like 1.63 watts per pound including the bike weights you specified.
Assuming they both have roughly the same form and climbing habits. they would be identical as far as theoretical time goes.
Some might argue that the lestened rotational weight and perhaps the greater stationary weight of the bike would give the lighter rider an advantage.
If it does then the advantage would be negligable
Now if they were on identical bikes, lets say 15 lb. then the lighter guy would have the advantage because his power to weight ratio(with bikes) just went up to 1.66 watts per pound and he therefore has the mathmatical advantage. that is still a miniscule difference.
So in answer either lose body weight- easier and cheaper.
Buy a buttload of light parts- same effect, just costly.
or, increase your power output at threshold.
Hope this answers your question.
Assuming all in-between things equal?Leisure
Aug 19, 2002 11:38 PM
Just speaking in theory, if the riders have the same percent bodyfat, muscle, bone structure, blah blah blah, the 200 pound rider has a subtle advantage for a couple of reasons. The first and more important is that the 200 pound rider has 5 pounds more body weight, a certain percentage of which is muscle and cardiovascular strength which would improve the power he can put into the climb. The second is that five more pounds will be in the bike which has very little suspension and has to be lifted over surface inconsistencies, while the rider can flex his body a bit making for a sort of derived "suspension". It's an extremely fine point on a bike, but engineers take these things more seriously when designing car suspensions.
Both of these points are small, though, and between random riders of either weight there will likely be more variance generated by other factors, such that you would likely not be able to see any definitive trend until you tabulated across a huge sample population. At that point you would have two bell curves with huge overlap but a slightly different mean.