jur

OK, it is simple, for a reason, which is to eliminate subjectiveness. That sort of subjectiveness which says "climbing is great, flat riding sucks" because I accept that some riders like it (in fact I _love_ climbing) while others hate it.

Subjectively, to me, climbing IS different, and thinking about it, it could be due to the fact that while climbing, there is a constant force on the pedals that you are battling against; slack off for a moment and your speed bleeds away. It requires sustained effort which in flat riding you can take a moment of rest without the speed bleeding off too much.

So here is something I didn't think of before:

Is climbing different due to the resisting force coming through the pedals? Eg, if you're riding a fixie slowly up a hill, if you don't keep on going every second, your going to roll to a stop and then backwards - there is a reversing force from the pedals. While riding flats, there is resistance but it is not driving backwards, it is merely slowing down.

Is that it?

jur

Haha, no, I am a university science graduate. But I don't like hype, I like hard facts and careful objective analysis, hence this thread. I don't mind being wrong at all, as long as it comes at me via those ways and not some cycling hack's personal opinion.

I am an engineer by trade.

jeff800

The question "Are you good at climbing?"
Answer: "I'm as good at climbing as I am in the flats minus the gravitational pull."

mac

That plus the angle that your body is in going up a mountain. I (unknowningly) use my abs a lot more when climbing.

stealthbiker

I think that you have to include physiology as well as physics in your model. People have different riding techniques, lung capacity, pain thresholds, etc. that influence how and why they ride better on flats versus hills. Physics may explain why a particular rider may do better on one than the other but I'm an accountant so what do I know?

Cyclaholic

Have you noticed that when you spend less time doing maths and more time riding uphill your speed going uphill gets better? ....hmmm, I wonder why that is?

jur

This quote is talking about vertical climbing rate. Put in a different way:

P (power output) = m * g * v, where m is combined body and bike mass, g is gravitational acceleration, v is vertical climbing rate.

So using your known climbing rate, and performing this calculation, you can calculate your maximum sustained power output.

Now you can use this same value for power output, divide by wind resistance, and calculate your maximum sustained flat speed:

S (max speed) = P / R, where R is wind resistance.

I'm saying your body does not know the difference between these two. If you were blindfolded, you would not be able to detect if you are climbing at a constant speed or riding flat at a constant speed.

If you disagree, where am I going wrong in the argument?

bshow1

That may be true (I'll be darned if I understand any of the math in this thread ), but in practice to climb you need continuous output of extra power. If you let up, you very rapidly stop and fall over (still clipped in; I've done it on an 18% grade ). On flat riding, you can adjust your power output more easily without slowing below the "stall" speed.

TexasGuy

I aint as good as i used to be, but I'm as good as I once was.

Steelrider

Doesn't this assume constants of speed and gearing? If you push a big gear on flat terrain, it does require effort. The faster you go, the more rolling resistance and drag coefficient come into play. I think the more important point is NOT that flat riding requires NO effort, but that you would have to duplicate the power output one would produce on a climb to get the same workout on flat terrain.


But fitness being equal, it is the power-to-weight ratio of the climbers that will determine how fast/far each will be able to climb.


You seem to be saying that two riders with identical power outputs can climb at the same rate, which would not be true at all because it ignores the weights that identical power outputs have to haul up the hill...


I don't understand why you see these as contradictory. Isn't it intuitive that a large, strong, rider can use superior power output to reach and maintain a high rate of speed on flat terrain, but struggle when having to use that power to lift his/her weight/mass upwards against gravity? Inertia is less affected by gravity on flat terrain than when trying to maintain that inertia against gravity when going up a hill. I don't think anyone needs to roll a ball on flat ground, then up a hill using the same amount of force to know which one will roll farther (or which will roll farther if using a heavy and light ball). All of this is really gross oversimplification (a specialty of mine...), but there are fewer forces working against the forward motion of a rider on flat terrain, so the one with greater power output (and often more weight) will have an advantage - an advantage that disappears when going up a hill... and, of course, none of this addresses technique, but there are whole other threads on that topic...

Steelrider

Not only am I not as good as I once was, but contrary to what Toby says, I'm not even sure I can be as good once as I ever was!

jur

I have not made it clear what my puzzlement is... I fully agree with all of your points.

Last night watching the TdF, Phil Liggett mentioned that Lance is not concerened about Tom Boonen because he can't climb... is this because Tom is a big guy?

All the refs to climbing and sprinting, does it all boil down to power to mass ratio, or are there additional factors?

I am genuinely puzzled as to what exactly makes one a good climber, besides fitness, and besides power to mass ratio. If someone had a good ratio, and was fit enough, would they necessarily be a good climber?

SteveE

I don't know about you, but even blindfolded I could feel a difference in the wind on what was left exposed on my face (or the rest of my body). In a vacuum you'd be correct. But in a vacuum you wouldn't pedal very far, either.

allgoo19

When I try to ride flat course as fast as I can, I have to pay attention to a few other things besides peddaling hard. Keeping my position aero, pulling my legs high close to my upper body and still breath easily. Often it's hard to decide where the compromise is and find myself keep changing the position.

On the other hand, climbing. I just pound it as hard as I can, much easier.

gattm99

I know little about physics, but this seems really simple to me.

ON FLAT, you expend a certain amount of energy to defeat wind resistence and friction to move forward

ON INCLINE you expend a certain amount of energy to defeat wind resistence, friction and gravity to move forward and farther from the center of the earth's core.

So with an equal amount of energy spent you will move less distance on an incline.

About climbers
This is probably 75% of what makes a good climber good. The other 25% is probably a mix of other vital statistics, (VO2max, LT, pain threshold)

NOW heres a question I would love to get answered, why do us fat people blast down hills way faster then skinny people!!!

26mi235

Well, here is my two cents. There is a climbing rate that is equivalent (in energy used) to a flat rate for each given gradient and wieght of a rider. The relationship of the speed of climbing versus flat is different for a heavy rider. The OP is not necessarily clear on this but this part is fine.

What thangs are "different" and does looking at the net energy applied capture the entire story. I use "net" here because there is a difference between the work performed (net) and the energy used (gross) because of inefficiencies in the engine and its mechanics (rider and the bike).

The climbing angles are different than on the flat, so that your position on the bike affects how effectively you perform your work. There are several useful situations to ponder. First, recumbant bikes suck on climbs. You push UP on the pedals while trying and cannot bring your body mass into play in the manner that humans evolved to do and hence you are not efficient in that position. Second, you have to have the right gearing or you end of under-geared on steeper climbs and cannot climb as efficiently; as slopes get really steep there are practical problems like not falling over. Third, it is virtually universely observed that the riders cadence is slower on a climb than on the flats. This hold whether the rider is a fast turnover rider or a slow one; the cadence for each falls even though the rates are different for each (compare Armstrong and Ullrich).

Third, mentally they are not the same. Riding much slower than you are used to has a psychological effect on riders, and many riders cannot climb well. (Riding into a strong wind is similar, although the dynamics are different as regards weight and body position can effect the necessary work in the wind and not on a clilmb in the same manner.) Riders are used to pulsing efforts in a group and doing what is necessary to stay in the group because the alternative is less desired. On a climb, as soon as you back off you slow down -- no coasting, no drafting along (well, especially for the pros, even a 6% slope is ridden fast enough that there is a drafting advantage).

Ok, flame away, I wrote this too late at night.

26mi235

That last question is very easy. The "force" from gravity is proportional to your mass, while the wind resistance that you have to overcome is proportional to the frontal area (there are air flow considerations but let us ignore that for now). I weight 135; a 270 rider on similar equipment has twice the gravitational force but only a little less wind resistence unless I adopt a more "aero" position. This assumes just coasting. Now if we add pedaling, consider a case where the 270lb rider can climb at the same rate on a steep hill, and hence has twice the work rate (net) that I do. Now, downhill, there is no gravitational potential to overcome and my lower work rate now translates into a slower speed. Magnus Beckstadt goes uphill slower than Roberto Heras and downhill faster (assuming no slowing for turns).

meb

There are several factors presenting multiple variables different between climbing vs. flats.

The first two have already been articulated ( and I’ll expand further on one):
1) by skinny , differing muscle groups due the lean of the change in pitch of the bike.

2) by Steve, aero vs. wt., aero drag for a larger rider relative a smaller rider goes up minutely. Assume a 160 lb rider vs. a 192 lb rider both identically proportioned. The 192 lb rider has (192/160) ^ (2/3) more frontal area than the 160 lb rider with an identical drag coefficient. Therefore, 12.9 % more rider induced aero drag than the 160 lber. Also, the larger rider’s bike has only slightly more aero drag than the lighter rider, so the larger rider’s aero drag is has increased sublinearly. But the mass needed to be raised in a climb has increased linearly.

3) strength goes up with size of the rider, but not linearly, sub linearly. A 192 lb rider is generally stronger than the 160 lb rider, but the 192 lb rider is not usually capable of putting out 20% more power. It takes the 192 lb rider 20 % more power to climb at the same rate as the 160 lb rider, but he usually doesn’t have that much more strength.


Regarding the incline controled pitch lean, yes it would be possible to design a climb specific bike to place the rider at an optimal climb power position for a specific incline, but then you’ve sacrificed the best position for the flats. You rarely have a course or route that is a pure constant incline climb.

jur

Thanks very much for all the replies. At the end of the day, although I understood all the principles explained in the posts before, I did not necessarily connect them to this question, so I certainly have a better understanding now.

I'm off now to lose another few pounds, and fitness training, and shedding every bit of excess mass on the bike, so I can leave my buddy behind on our monthly Mt Dandenong race.

He's racing a brand new Cannondale flat bar racer, I'm racing an ancient Giant hybrid which is delightfully light

Keith99

Sooo a tri geek might say...

Since every rate of bike riding equates to a certian power output, and since every rate of swimming equates to a certian power output how is bike riding different from swimming?

The only real difference here is that in climbing vrs flats the activity is similar enough that the question does not look absurd. Many of the posts have done a very good job of showing that while flats and hills look the same they are in fact different. I just provide the reduction to absurdity.

jur

Hmmm... like many of the posters in this thread, you have missed the actual point. The point you make is childishly simple and was never questioned in the first place.

sorebutt

here is an idea, hop on your bike and ride a flat course, and then a steep climb, and when you are done come back to us and tell us what did you find out..

jur

Why don't you READ before you post. Been said & answered

TheKillerPenguin

I sympathize, jur.

ChAnMaN

wait i didnt even post in this thread? ohh i get it, you know im going to clear things up so you just agree with my post before i even post it.

well i dont really want to use my brain right now and do a bunch of math, but common sense tells me that the increased resistence due to gravity when climbing is much greater then the decrese in wind resistence due to slowing down. therefor climbing is harder.