Yes, I know it’s a stupid question at face value and the answer will involve physics and raising a mass along an inclined plane, but…

If a bike has got gears, then it should be simple enough to select an appropriate gear for the conditions so that riding up hill takes no more effort than riding along the flat, albeit slower.

It never seems to work like that though, does it ?

My guess is that human nature is involved and a rider who sets off with the intention of maintaining a constant effort will, in fact, subconsciously try to maintain a constant speed.

So, say it takes 250w to maintain 20km/h on the flat.
When the rider gets to a hill and finds that 250w will only move him at 10km/h, he will instinctively compromise and increase his output to 350w to maintain 15km/h.

Does that sound believable ?
Is there any science behind it, like blind tests done with a heart rate monitor or power meter ?

You can’t freewheel uphill so it’s sustained effort unlike flat/downhill where you can take a break from pedalling if you want.

Does that sound believable ?
Is there any science behind it, like blind tests done with a heart rate monitor or power meter ?

It does and ime it takes a real mental effort to try and maintain a steady hr or power output when riding up hill, as yes, you go slower. That’s often frustrating. If you set out with that idea in the front of your mind, and a way to measure your effort it is do-able though.

No idea about this, but low gear means you’re spinning, therefore ‘feels’ different (harder after a time?)

….and then someone walks past you and all the determination, focus and physics goes out of the window.

It doesn’t take much power to maintain a steady speed (say 15mph) on the flat (assuming there isn’t a huge headwind). That same power on even a moderate hill would have you going slower than walking pace. So, you have to either put in more effort or get off and walk.

EDIT: A few rough numbers from analyticcycling.com

100W on the flat (rough but paved road) = 16 mph
100W on the same road with a 10% gradient = 2.8 mph

roverpig, that raises another point.
Cycling is obviously more efficient than walking on the flat, but there must be a maximum gradient where walking becomes more efficient than cycling.
I wonder what that is ?

Part of my reason for asking the original question was that I cycle to work, then put on my overalls and work pretty much on my own in a big workshop.
I know that other people who work in a suit & tie environment, in close proximity to their colleagues or customers, sometimes worry about arriving at work all hot and sweaty.
If they walked to work, it wouldn’t be a problem, even if there was a steep hill or steps on the way, so why is it a problem on a bike ?
Perhaps they should wear a HRM and rigidly stick below a maximum HR, regardless of how slow they are riding.

smooth shallow road climbs are pretty easy, sit, spin, don’t keep looking at the summit and you get there…eventually.
XC climbs especially steep ones are a whole other level, weight shifted backwards which you have to counter (not an ideal pedalling position), rocks, roots and steps to negotiate, constant weight shifts to keep traction for the rear and stop the front lifting, slower speeds and less weight on the front equal more wobble and getting knocked off line and you occasionally end up switchbacking up an otherwise straight wide bit of trail, all adds up to more effort, mental aswell as physical. Climbing up to Hayeswater last month, near the top the gradient isn’t too bad at all but the gravel spits traction so much you are hunkered down to keep traction and every pedal stroke is much harder than it should be.

I’m not sure if walking ever become more efficient than cycling. Although I’ve often heard people say that it would be just as quick to get off and walk, I’ve found that I’m always faster if I stay on the bike. There just comes a point where you can’t put out enough power to maintain a high enough speed to be able to keep balance.

If they walked to work, it wouldn’t be a problem, even if there was a steep hill or steps on the way, so why is it a problem on a bike ?

Because you can walk as slowly as you like (plus you don’t have the weight of the bike to lug up the hill), but on a bike you have to maintain a certain minimum speed in order to stay upright and that requires a fair bit of power for even a moderate hill.

but there must be a maximum gradient where walking becomes more efficient than cycling

pristine tarmac I don’t think you’ll get a gradient where walking is more efficient, tho you may have to have a specialised bike with a 36″ rear and 20″ front wheel just to keep your weight between the wheels whilst seated.

but isn’t efficiency in this case power in vs work done? At silly steep angles the power your body is producing may be efficiently turned into forward motion but the effort is completely unsustainable by your muscles. Walking, step, step rest for a breather, step, step etc may be less efficient but more sustainable for you.

Or something, I’m pretty shit at physics

There’s probably loads done in similar topics that can be translated to the biking world. Look to Kinematics for an explanation and an equation of why walking up hills is harder than down them. It’s the same thing with bikes and is to do with you trying to move your mass against gravity.

clearly a steeper hill is harder to get up than a gradual incline. This is because the movement or pull from gravity is more sudden. For a noggin it should be easy to work out – aren’t gravity and your mass constants?

When riding on the flat you only need to overcome the rolling resistance and friction inherent in the bike and wind resistance. Riding up hill you need to overcome all that, and gravity. You need to do more work.

To maintain a steady speed you can maintain your cadence and increase the force you apply to the pedals, or you can keep the force and change the cadence (ie: go down the gears) but you’re still doing more work. You can’t just go slower and keep the difficulty the same for one simple reason:

If you stopped pedalling, you’d roll backwards. You have to exert some effort to just stay still, unlike when on the flat. That’s the ‘extra effort’.

100W on the flat (rough but paved road) = 16 mph
100W on the same road with a 10% gradient = 2.8 mph

and that’s presumably 100W put through the pedals(?), factor in the other stuff I mentioned and you’re probably doing more than 100W of effort overall.

I guess you’d need a power meter measuring the output to the cranks and a HR monitor approximating how hard your body is working. And do you want pure numbers or real world? Real world ride a normal bike, pure numbers use an adjustable bike so the pedalling position can remain constant whatever the gradient. Again tarmac will be easier to measure coz there’s so much technique involved in XC you probably get a lot of inconsistency in different runs.

100W on the flat (rough but paved road) = 16 mph
100W on the same road with a 10% gradient = 2.8 mph

Out of interest, I plugged some numbers into an online calculator, and in order to climb Alpe d’Huez in 62 minutes (which I did last summer), my average output was 239 watts. So roughly an 8% gradient at 12kph is 2.4 times harder than riding on the flat at 26kph. Quite a difference!

MidlandTrailquestsGraham – Member

If they walked to work, it wouldn’t be a problem, even if there was a steep hill or steps on the way, so why is it a problem on a bike ?

That’s just about duration- cycling the same route almost certainly uses less energy but it does it far faster so you exceed your head elimination limit and warm up.

100W on the flat (rough but paved road) = 16 mph
100W on the same road with a 10% gradient = 2.8 mph

That’s interesting.
I guess even an average cyclist could sustain 100w without raising a sweat.
10% is a bit steep, but even so, not many people would be content to plod up at walking pace, so I suppose it’s instinct to up the power output to try to maintain a more reasonable speed.

Throw in to all this, that the slower you are going, the more effort you will expend just to balance the bike. Because we’re not 100% efficient at that (track standing is hard work right…). So you either instinctively speed up to avoid this, or if you do insist on going that slow, it’s going to have an effect.

The reason is perception. We want to climb at a “reasonable” pace (not walking pace), but in fact it should be power (or perceived effort as opposed to speed) that is maintained. I pedal on the flat at 200W, but need to climb at 300W because 200W seems far too slow!

I can cycle to work without sweating on all but the hottest days when I’d sweat walking
However one of problems, or benefits, of road cycling is that you generate your own cooling breeze. Great until the bike shed’s reached & the breeze is lost but the body still needs to shed heat.
Slowing down well before getting to work would mostly solve this but it’s counter to do so.

Gravity is surely the biggest challenge

A small push downhill and it would keep going, flat would go for a little bit, uphill would go for an even shorter distance

Try riding with a power meter….and at a constant power.

I think the psychology of it does have a big part to play, I mean you’re probably on a bike in the first place partly because walking seems a bit on the slow side, so you will naturally go to the higher end of what feels (to the individual) like an appropriate, sustainable effort for any given section of a ride…

Also the average cyclist is probably adjusting their output based not just on current conditions but also on what they know or can see coming up i.e you might put in a much higher effort for a short sharp climb knowing its not going require a longer, sustained, high output and there’s a good chance of recovery at the top, Vs an increased but not quite as high effort for a longer climb and a steady sustainable output on the flat.

In both cases the rider will be trying to match their output to the time/distance over which they estimate they can sustain it…

Even without HRMs and Power meters most people learn how to adjust/pace themselves through their general experience of exercising, and listening to their body…

I’d imagine it must take a heck of a lot of discipline to actually stick to a specific, low HR or Wattage for a climb when you know you can push harder…

A friends girlfriend once drove his car home as fast as she could because it was making a horrible noise so she wanted to spend the least possible time driving it thinking that would result in the least damage – it was a very expensive decision.
I think a similar mentality kicks in on a hill – we think the sooner it’s over the less likely the engines going to blow up.

It’s interesting when you ride with someone slower than you (and you are consciously trying to match their speed)

Climbing becomes much much “easier” – obvious maybe but I think that proves how much more inclined you are to push the effort when you are climbing

I’d imagine it must take a heck of a lot of discipline to actually stick to a specific, low HR or Wattage for a climb when you know you can push harder…

It is, low zone rides are painfully frustrating. Even a slight rise can have you spinning a very low gear.

It doesn’t actually take that much of a hill for you to quickly run out of gears (at least on a road bike) if you are trying to maintain an easy power. You don’t have much choice other than to up the power just to keep going.

100W on the flat (rough but paved road) = 16 mph
100W on the same road with a 10% gradient = 2.8 mph

Weight plays a huge part in this too. If I’m riding with a mate who’s 10kg lighter than me we’ll both still be putting out roughly the same amount of power for a given speed on the flat (assuming I’m no less aero.) On the hills though I’m going to have to put out a lot more power than he is for a given speed. The steeper the gradient the bigger the difference in power becomes.

What shoe size makes the hills come alive when walking?

I can cycle to work without sweating on all but the hottest days when I’d sweat walking
However one of problems, or benefits, of road cycling is that you generate your own cooling breeze. Great until the bike shed’s reached & the breeze is lost but the body still needs to shed heat.
Slowing down well before getting to work would mostly solve this but it’s counter to do so.

This, on any day other than very cold ones I get sweaty walking in, but not riding in. I do tend to cruise the last few 100m to cool down more so I don’t overheat once stopped though.

I believe I use more (certainly different) muscle groups when climbing steep hills so the same effort (HR or power) feels different uphill. Not necessarily harder, just different.
Oddly cycling into a headwind at a set HR feels harder than cycling with a tailwind for the exact same HR.

More sustained, and generally higher, power output.

Riding at high power output on the flat (fast) is just as exhausting; you are overcoming more drag at higher speeds too (most noticeable on the road bike, of course).

So many unscientific replies here it’s making me shudder!

Because I am fat.

And unfit.

Let’s have your scientific answer then 😉

Actually I’ll give one, which I hope might meet your approval. I don’t think anybody has yet mentioned that one of the major factors which makes hills feel different is on a micro rather than macro scale. You don’t put in power all the way round the pedal stroke – on the flat you won’t slow down significantly during a pedal stroke, but on a hill you will. So a lot of the added difficulty is that you have to pedal right around the stroke, and if like any normal human being you don’t then you’re actually having to accelerate the bike up to speed again all the time.

I cannot see this above but when you are riding uphill there is a constant decelerative force applied to you. If you’ve ever had an apple drop on your head or not floated off into the sky you will have encountered it as it’s called gravity.

When going uphill gravity is attempting to decelerate you at up to 9.8m/s^2 (or “g”). The full effect of g only applies when going vertically up so the deceleration you actually experience is only a proportion of g, which gets bigger as the slope gets steeper.

On a slope of 30deg you would experience 0.5g (trust me on the trigonometry).

Effectively on a 30degree slope you will be experiencing a decelerative force (ie gravity pulling you down the angle of the slope) of

Slowing force = body weight X 0.5g

So if we say g is 10 (for rounding) and I weigh 100kg (rounding of a different sort) then on a 30 degree slope there is 10*100*0.5 = 500 Newtons of Force trying to drag my lardy butt back to the bottom of the hill and that’s before you add the 30lb of pig iron that is my regular bike.

I have to generate oomph to overcome that force and move forward.

Also by gaining height you are having to overcome the potential energy you aquire which is

PE=mgh (mass * g [see above] *h)

So for a 200m vertical height increase, I have gained 100 * 10 * 200 Joules of energy (=200,000J). This applies if I ride up at 1mph or 20mph as it is the energy gain from the increased altitude.

For every speed increase on the hill I must also add 1/2 mv^2 of energy to, so to accelerate by 2m/s of velocity I need 100*2*2=400 Joules. ALTHOUGH THIS ALSO APPLIES TO ACCELERATION ON THE FLAT.

Hopefully I haven’t cocked up the science too much.

Physics aside there is also a psychological aspect. Some start a big climb with a sick grin, others with a little wimper.

Has anyone said ‘Because it’s uphill, Durrrrr!’ yet? 😀

So, say it takes 250w to maintain 20km/h on the flat.
When the rider gets to a hill and finds that 250w will only move him at 10km/h, he will instinctively compromise and increase his output to 350w to maintain 15km/h.

Perhaps part of it is the law of diminishing returns – particularly when riding solo. You can clip along the flat at 20kph fairly easily (250watts as per your example – do you ride a fatbike? 😀 ). If you double the effort (500 watts), you won’t go twice as fast. I don’t know the maths but from experience I’d guess you might go 50% faster.

Whereas on a climb the speeds involved are typically much lower, and wind resistance doesn’t form a significant problem. Therefore any extra effort you put in will give an (almost) proportional increase in speed.

If double the effort = double the speed, you’re more inclined to subconsciously put the effort in?

It’s worth noting that when cycling along on the flat, there are two drag functions, with a rolling friction drag coefficient being proportional to speed and an aerodynamic drag force being proportional to speed SQUARED!. This means that it gets increasingly difficult to go faster and faster as the speed increases, however initially it is quite easy to double your speed before the aerodynamic drag becomes the principal limiting force.

But, climbing is a linear term, in that work done is force x distance. So any increase in speed requires an immediate increase in pedaling effort, even if your initial speed is very low.

This means that increasing your speed on the flat is easy at first, and then becomes very hard as you get faster and faster, whereas on a climb any increase in speed immediately feels like hard work!