So Why do heavy guys do better on Flats?
- Thread starter graywulf
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I think it's mostly just because they are heavier in terms of muscle, which means more and stronger muscle mass overall. Bigger guys have this advantage in most sports.
Power-to-weight ratio favours them on flats when power matters but weight itself doesn't matter as much once the bike is rolling at speed, whereas it favours smaller guys on climbs where weight starts making more difference, assuming all else is equal.
Power-to-weight ratio favours them on flats when power matters but weight itself doesn't matter as much once the bike is rolling at speed, whereas it favours smaller guys on climbs where weight starts making more difference, assuming all else is equal.
longfemur said:
Weight does matter in terms of inertia. A 200 lb rider moving at 20 mph has 33% more inertia than a 150 lb rider. That a very significant difference. That means a given amount of aerodynamic drag causes the 200 lb guy to slow down significantly less than the small guy. The same goes for the effect of drivetrain friction and rolling resistance.
I don't think the OP was asking why stronger riders are fast on flats. That's a non-starter. Of course, I could be wrong about his/her intent.
I agree that inertia may be part of it too... but I think bigger frames mean bigger, longer muscles, bigger heart, bigger lungs, etc.
By fast, I really meant the ability to keep going at a fast pace almost indefinitely. Fitness being equal, I've always found bigger guys can do that better than I can, but as long as I can hang in there, I'm better on the hills.
By fast, I really meant the ability to keep going at a fast pace almost indefinitely. Fitness being equal, I've always found bigger guys can do that better than I can, but as long as I can hang in there, I'm better on the hills.
As always, it depends on what we're talking about in terms of weight. Most people will be somewhere in between the two extremes, but in cycling, 180 lbs is a lot more than what the 125 lb climber weighs. It's much more likely that the 180 lb guy will be a better "rouleur" than the 125 lb one.
My guess is that they are bigger, so they have more output. (bigger as in muscles, lungs elc). Someone already mentioned this.
Now put them on a curvy hilly area and I think the lighter guy will win, for his less rolling resistance (heavy on tires in corners elc) and gravity pull when climbing.. well more gravity pull in corners too, thus the more rolling resistance on the tires?
Im new to road biking especially, but thats what I think =P
Now put them on a curvy hilly area and I think the lighter guy will win, for his less rolling resistance (heavy on tires in corners elc) and gravity pull when climbing.. well more gravity pull in corners too, thus the more rolling resistance on the tires?
Im new to road biking especially, but thats what I think =P
This perception exists because some of the heavier riders also have the advantage of being able to generate bigger wattage by virtue of their physique. Unfortunately for most of the bigger riders, this advantage is negated when the road turns skyward.
graywulf said:
Weight matters to it. Believe it or not heavier guys don't use as much energy on flats as lighter guys. You can do a simple experiment, buy some groceries and put them in your backpack, and that goes on your shoulders. I guarantee you will ride faster and be less tired. Essentially, weight in your backpack is doing the pedal work. A light guy has to use his muscles far more in this scenario.
I'm a city rider, that means a road bike along side of cars, difference between going to grocery store and back in terms of speeds is a lot. I could sustain 18 mph going to the store with empty pack, while maintaining my regular breathing somewhat mind you, back with pack fully loaded I could be going 25 with the same close to normal breathing. And this is not race, this is city pleasure riding, keep that in mind. And it only works on flats and down hill, going up hill with more weight is hard, I have triple and I down shift onto smallest cog when I have extra weight, without any bags I could take my hill in middle cog. Which is the cog I use for flats as well.
You guys ever tried riding in a flat with loaded backpack and 20 mile wind in your back? I once reached 38 mph like that.
This thread is full of **** science. There is only one reason why bigger riders tend to be faster and that is becuase they produce more power in relation to the aerodynamic drag forces that act on them.
Momentum has almost nothing to do with it unless you are trying to be a human battering ram- or if you go down a big hill onto a flat, the bigger rider will hold their speed because they contain a greater amount of kinetic energy. Because momentum = 2 * KE/V then momentum is interchangeable with KE if we control for velocity (as in you are both going down hill at the same speed.) So in a very convoluted way and in a very special circumstance, it may be vaguely important.
But this cannot be applied to racing situations, unless you have a sprint very close to the base of a descent, and even here I can't see the effect being that great.
There are two other foces that a rider must overcome- gravity and rolling resistance. Both scale according to weight so in these areas the rider with the highest power to weight ratio will benefit. Thus on very dead roads, or climbs, those with high power to weight get an advantage, whereas on silky smooth roads, or flat or downhill sections, those with high power to drag get an advantage.
Momentum has almost nothing to do with it unless you are trying to be a human battering ram- or if you go down a big hill onto a flat, the bigger rider will hold their speed because they contain a greater amount of kinetic energy. Because momentum = 2 * KE/V then momentum is interchangeable with KE if we control for velocity (as in you are both going down hill at the same speed.) So in a very convoluted way and in a very special circumstance, it may be vaguely important.
But this cannot be applied to racing situations, unless you have a sprint very close to the base of a descent, and even here I can't see the effect being that great.
There are two other foces that a rider must overcome- gravity and rolling resistance. Both scale according to weight so in these areas the rider with the highest power to weight ratio will benefit. Thus on very dead roads, or climbs, those with high power to weight get an advantage, whereas on silky smooth roads, or flat or downhill sections, those with high power to drag get an advantage.
You think they go fast on the flats?
You should see them going downhill in a straight line...
Our club trains every Sunday on a flat stretch and depending on the wind the heavier guys have an advantage. Especially if there is a tail wind. They are disadvantaged in a head wind though as the momentum is fighting the wind. Assuming a heavier rider is bigger they also have more surface area/drag.
You should see them going downhill in a straight line...
Our club trains every Sunday on a flat stretch and depending on the wind the heavier guys have an advantage. Especially if there is a tail wind. They are disadvantaged in a head wind though as the momentum is fighting the wind. Assuming a heavier rider is bigger they also have more surface area/drag.
JAPANic said:
Moving at the same speed, the heavier guys do have more inertia. Always. They are, however, affected less by wind than lighter guys. This assumes that a light rider and a heavier rider have the same surface area presented to the relative wind. As velocities increase, inertia (momentum) will be less and less of a benefit because momentum only varies linearly with velocity. Aero drag changes with the square of the velocity
11ring said:
this is the correct reason... it has to do with the fact that a smaller rider has greater aerodynamic drag to power ratio than a larger guy.
on the flat how fast you go is primarily determined by how much power you can produce to oppose your aerodynamic drag. weight is not much an issue since you don't have to drag your fat carcass up hill. aero drag is frontal area x drag coefficient.. basically how aero your shape is. can imagine that a rectangular block and a section of airplane wing could have the same surface area but very different drag.
going up hill fast is almost all about power to weight or more so the steeper the climbs since speeds are much more reduced and aero drag is less and less important.
look at it this way to make is simple... say riders have the shape of cubes.
a 1x1x1 cube has a frontal area of 1 and a weight of 1
a 2x2x2 cube has a frontal area of 2 but a weight of 8
the larger rider has larger heart, larger muscles with more vasculature, more mitichondria etc and can produce more power, but he also has more drag to deal with given his larger size, but his greater power is in proportion to his increase in power given his size but that greater power comes at a cost.. his size increases his weight as the cube so his increased power doesn't make up for his increase in weight when going uphill.
you can also see that the weight effect is going to be much more pronounced than the frontal area/drag effect so that why a guys like Contador and Liphiemer... even Armstrong is not a particularly big guy... who have very large power outputs for their size can still beat larger guys. it's just in general larger guys have a better chance on the flat since their power outputs are pretty much proportional to there larger drag numbers... compared to their smaller competition.
there might be some small momentum affect.. but the major factor is that larger guys have a slight advantage in terms of frontal area to power than smaller guys.
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