jur

Does climbing differ from flat riding? Before you jump to conclusions and say "of course it does", read on...

1) Climbing involves raising your mass from one level to another. The amount of potential energy you gain by climbing is E = mgh, where m is mass in kg, g is gravitational constant in m/s/s, and h is vertical height in m.

This equation explains why ANY climbing requires effort, regardless of how fast you climb. It also explains why slow flat riding requires no effort - no energy is gained.

2) Your fitness will dictate exactly how fast you can climb. Ignoring wind resistance (just for now), the grade of the road together with your forward speed determines the rate of climbing, or the rate at which you gain potential energy. A constant rate of gaining energy equates to a certain power output by your body. And the amount of power (in watts) your body can put out at a sustained level is determined by your fitness.

So, vertical climbing rate is directly determined by your fitness.

Now on to flat riding.

3) Flat riding (by flat I mean zero gradient) involves no gain of energy, so from that point of view, no effort. However, there is wind resistance (and rolling resistance and so on), which requires effort to overcome.

4) Wind resistance is a function of your speed. This means, that for every constant speed, there is a certain power output required to maintain that speed. The higher the speed, the higher power (in watts) is required to maintain that speed.

So here is the final part of the argument:

Since every rate of climbing equates to a certain power output, and since every flat constant speed also equates to a certain power output, it follows that climbing at a certain rate is the same as riding flat at a certain speed, ifthose two have the same power.

Soooo, how is climbing different from flat riding??? Is the question "Are you a good climber" meaningful at all? If someone answers, no they suck at climbing but are OK on the flats, that is contradictory.

SpongeDad

At the risk of oversimplifying -

A fat load can still ride fast as hell on the flats because (s)he's got giant powerful legs and there's relatively not much of a penalty for overall mass (cross section goes up only slightly for a significant change in mass). This same fat load will suffer horribly on a steep grade because now (s)he's paying a penalty for the weight.

Now the pros aren't fat loads, but the big frame guys still are carrying a lot of weight in the upper body that isn't moving the bike forward.

STEVO820

when going uphill you are bearing the weight which is not good so the lighter the better but if you are flat you arent bearing the weight. for down hill would a heavier person dominate due to momentum?

-Steve

jur

What you guys are saying is reflected in the equation I gave. Modifying it for speed instead of height:
P = mgv, where v is vertical speed, and P is power.

If your mass is more, the same power output will result in a lower climbing rate, but perhaps a similar flat speed since wind resistance is not influenced much.

This also reveals that the question "are you good at climbing" is indeed meaningless by itself, it must always be answered compared to some standard.

If you had a particular fitness, resulting in a particular climbing rate, and that might be "good", then if you did a lot of body building and added a lot of muscle mass but had the same fitness, then you would be worse off at climbing compared to before.

skinnyone

Ok in essence Climbing is not different from flat riding because you are overcoming resistance period.. The power output being constant, you should only see a drop in speed as the resitance increases..

Here is one more variable to think of.. Body position.. Your Medulla Oblongata is going to try to keep your body straight vertically to get you to the same position as in the flats.. no?.. So that means different muscles get used and power output would vary depending on how strong those muscles are .. Different position means that your body has to adapt to the new one and prevent you from going backwards...

SteveE

Flat = a function of power to frontal area (think wind resistance)
Climbing = a function of power to mass (think gravity)

They are not the same thing.

STEVO820

what are you trying to prove? before people start to fight over this. i dont think this going to go anywhere. mods should close this thread before people start fighting over something stupid.

jur

Hmmm, I wonder... If you are in the saddle, then the geometry of rider/bike is constant, that tells me the same muscles are used. If you are standing on the pedals, I guess the rider will be leaning slightly forward compared to a flat riding position, so his arm geometry would be different but wouldn't the leg and body geometry be the same again? Especially for a rider who is very conditioned, they would automatically adopt a position which is essentially the same for both conditions so as to get maximum effort?

chinamn

SO i guess you are recent student of physics. Well your logic is slightly wrong. Yes you are right about gravitational potential E = mgh but you are forgetting kinetic potential, E = .5*m*v^2. Once you factor that in both equations, it shows that climbing up a hill requires an additional gravitational pontential energy.

As you mention performing both a the same power (watts) since climbing requires has both gravitional and kinetic potential energies and riding on flat ground only has the kinetic potential. Since some of your power would be disapated in gravitional and kinetic for climbinb, you will ride faster on level ground.


Thus the reason why climbing is harder.

skinnyone

I like chanmans explanation better but anyway.. you move in your saddle to keep you upright, as the bike is on an incline.. Even if you are conditioned, you are talking about a bunch of musles, not one single muscle. Power is derived from different muscle groups in different positions..

hwttdz

Well the kinetic energy only comes into effect if you vary your speed, which in real life happens, it's impossible to maintain a perfectly constant speed, but as this is a theoretical discussion I think it's safe to disregard this. Arguments could be made both ways as to whether this effect is greater climbing due to greater fluctuations in speed, or on the flats due to the velocity being higher.

On a different note, though possibly not the most applicable I think discussions of this nature are generally interesting, and it seems to be quite a civil discussion at that.

For those who have some time:
So the way that has been mentioned to look at this is a person with a given “cross sectional” area (more like frontal area), producing a given power, with a given amount of mass, will have two speeds corresponding to flat land and different inclines (dependent on hundreds of other things, from the density of the air to the type of clothing they’re wearing, but I think this is a reasonable rough assumption). So a proportionally high frontal area to mass, produces a good climber and likewise a proportionally low frontal area to mass produces a good flat land rider. Frontal area is roughly second order and mass is roughly third order proportional to radius (of course people aren’t spherical, but…). So people with large radius are better at flats and people with small radius are better at going up hills, look we have a hypothesis that accurately predicts observed data (yay for us).

The possibly more interesting question is, is power constant from flat lands to climbing? I’d think that climbing uses a somewhat different position and also usually involves working at a different cadence, so someone could be relatively better at climbing or flats relative to their “radius” depending on how they react to the changes in these factors? That’s something to chew on isn’t it?

jur

Kinetic energy does not enter into the equation if it stays constant.

(And no, your guess is wrong, I'm not a recent student of physics. )

STEVO820

i think the real function is E=PYDB. P=pedal, Y=Your, D=Damn, B=Bike. because the flux compacity is a constant variable due to each riders stance, weight, height, body fat %, as well as how many watts the riders body produces. therfore it is illlogcal for a rider of an x weight to challange a rider of y height because the variable as so different. and if the E=mpg is 0 you wont be able to drive you car because you would have zero miles per gallon. thus a nestle chocolate drumstick would have a negative effect on a x weight rider and a positve effect on a y height rider. but also you need to take in how much OCP (woot woot) bling is being added. if x y and z riders or on pimped out OCP bikes as opposed to crap garage sale 10 speeds they flux variation compacity controlled variable is false therefore the would is flat not round but if the would is round wouldnt we always be climbing? and if we think we are climbing we are actually riding up side down which will piss of god because we then defy gravity. so i believe that $412.25 a month is a great price to pay for this kind of rambleing to go on and on and on and on.

skinnyone

Truly funny but a wtf moment as there seemed to be a bit of nice analysis going on..

chinamn

but that is not what you are comparing, what you saying is that lifting an object is harder than leaving at one level. So obviously it doesnt differ. You are talking about climbing which involves forward movement and evelation increase.

STEVO820

thats not suppose to be funny that took some hard analysis like i had to look at my nestle drumstick wrapper to see how to spell nestle

jur

I think you misunderstood.
Imagine riding blindfolded. Maintain a constant cadence by shifting, and maintain a constant effort. Your speed is varying as you ride on the flat or as you are climbing, but your legs don't know the difference to what's happening. It would be like riding a trainer and just varying the bike's pitch.

Now that's the question that has been raised, is the effort different due to the different pitch? I'm not sure here, in the saddle the geometry remains the same for legs vs pedals, and even standing up it might be argued that the geometry of legs vs pedals are the same.

^_Mike_^

From a physics standpoint climbing and flat riding may be identical. But THEORY may vary greatly from actual PRACTICE. You may perfectly understand the physics behind climbing and flat riding but that does not automatically endow you with perfect climbing technique.

The question "Are you a good at climbing?" may be meaningless in theory. But in real life, it is a good question.

STEVO820

see how long you will last blindfolded

jur

Great - this is exactly what I'm after. I'm trying to find out if there is a real difference. By posing the question in an ideal theoretical manner, I am trying to get rid of subjective factors. I am trying to see if there is any basis to all the climbing hype, like "Zen and the Art of Climbing". Reasoning from a purely theoretical point, I don't see a basis.

So, you say there is something like Perfect Climbing Technique. Without going into much detail, how is climbing technique different from just being fit and pedalling hard up the hill? How would my identical twin that is as fit as me but having learned climbing technique, beat me?

skinnyone

Where is Terry... You with us??

Body2big

Now I am new but I can think of a few techniques Ive seen and some used. Knowing when to shift so you don't lose any momentum, Knowing when to stand if needed at all, if riding together how to draft before the climb, Knowing your bike and body. I may be wrong but It sounds good not as good as the nestle drumstick theory

Shawn

my58vw

NO NO NO! You are mistaken (except the first comment about kenetic and potential)

Ok here we go... there are more factors than just kenetic and potential energy when it comes to climbing. Physics is never wrong in this respect. When you go up a hill kenetic and potential energy are both in play, kenetic then equals potential energy at a given time, think of a ball rolling down a hill... BUT

KE = 1/2 m * v^2 (1/2 * mass * velocity)
PE = M * G * H (mass * gravitational constant * height)

Think of kenetic and potential energy for a second. An object at ground level has NO potential energy (assuming flat surface), but an object at the top of a hill has lots of potential energy. Think of potential energy as energy of posistion, the higher you go the more potential energy that must be in play. The potential energy comes from the riders energy output and the work inputed though the pedals (think WATTs) (Watts = F (KE and PE + air, etc) * time (s). Therefore the higher you go the more energy you have to put out... that is what makes climbing harder...

Now all that energy that you put out is transformed into kenetic energy as you go down the hill, in additional to the kenetic energy applied via pedaling... so you go suprising FAST.

Kenetic energy is the energy of motion, thus velocity. It does not matter if you are going down a hill, up a hill, on flats, freefall, etc. It has NO dependence on height. Going 40 MPH on flats produces the same amount of kenetic energy as going down or up a hill. You can go faster down a hill because you have more kenetic energy from pushing of gravity as a vector component of your direction.

Well you say, what about air resistance... yes air resistance is a big big factor, expecially at high speeds. On flat roads air resistance is the highest factor in speed regulation. On hills it is regulatory but not as much as on flats because the speed is less... but going up a hill you have less kenetic energy in your favor (lower speed) so the effect of air is less.

To sum up...

Hills and Flats

Energy = F * distance = (KE (speed) + PE (height) + air resistance + friction ...) * distance

Flats - No PE, All KE and air resistance.

Hills - Lots of PE, less KE and air resistance

Then why are hills harder... because gravity is a much bigger force than air resistance... and it turns into a frontal area issue... in short lighter riders are better on hills because they have less PE, heavier riders are better on flats because they have more KE per frontal area... less drag per watt...

Physics lesson over... (I have a degree in physics and my area of speciality is in dynamics, I hope I know my stuff...)

my58vw

Momentum is another story all together...

P (momentum) = m * v ---> heavier riders have more momentum than a lighter rider... think longer to stop... thus a lighter rider will have to work harder to maintain momentum than a heavier rider... but because heavier riders have to deal with more PE they have to work harder. That is also why heavier riders go down hills faster... More P because they have more PE...

jur

I'm afraid you are not very rigorous in your arguments... and there are some obvious mistakes there... and remember that kinetic energy does not enter into the equation if it remains constant.

Leaving that aside for the moment, where EXACTLY am I mistaken?