Pedalling up a hill. Which is more efficient?

Let’s say I’m on my bicycle and I’m approaching a small hill, say 20 to 30ft vertical gain.

I want to crest the hill having used as little energy as possible in getting there.

Should I sprint and build up speed so that the additional speed carries me up the hill to the top?

Or should I save that energy until I reach the bottom of the hill and then just grind my way up?

My instincts tell me that it doesn’t make a difference. I’ve simply moved a mass from a lower position to a higher position in both cases.

Am I missing something?

Yes, you’ve missed something, which is that your muscles are not equally efficient over their entire range of contraction, they are not equally efficient at all loads, and not all muscles are equally efficient.

The correct answer varies depending on your weight, fitness, slope and length of hill and so forth. But generally you use less energy building up momentum on level ground.

When given the choice, your body will apply force using the muscles that are able to do so most efficiently, over the range that is the most efficient for the muscles being used and at the force that is most efficient for those muscles. So when you are on level ground and you ask your body to produce more speed, it will naturally do it using mainly the leg muscles, and in the most efficient range of the leg muscles. And it will build up momentum gradually so that the muscles are always generating force in the most efficient range

However, when you are struggling up a hill, your body has no choice. It needs to generate force using a broad range of muscles including the arms, shoulders and abdominals, and it needs to generate force over the most of the contraction range of those muscles and it needs to generate a minimum amount of force constantly.

That all makes it much more efficient to build up momentum of the flat, and use that to coast over the hill.

As a* reductio ad absurdum *example, imagine a typical skate ramp. Almost anybody at any level of fitness could build up enough momentum to coast from the base of that ramp to the top. And conversely, most people would struggle to start their bike from the bottom of that ramp and pedal to the top. They simply would not have the strength in their arms and abs to pull the weight of their body the top from a dead stop.

Which proves that the most efficient way to get to the top is via momentum. A dead start is so inefficient that the machine can’t even manage to do it given an infinite amount of time and infinite amount of energy.

Note that this isn’t unique to the human body. All machines have a range over which they are most efficient. You won’t start car or truck moving on the types of hills which they will coast over easily at 80mph.

Air resistance is proportional to the square of the velocity. Much of the energy used to speed you up is wasted in pushing the air out of the way faster.

If your pedaling cadence drops too low and the power output increases to a certain level, your muscles begin to switch from aerobic to anaerobic mode, which is less efficient. A higher percentage of the calories burned in your body wind up as waste heat.

So which method is more efficient? I think it depends on the speeds involved and the weight of the cyclist. A lightweight cyclist might do better powering up the hill, being less likely to go anaerobic; a heavy cyclist might do better with the sprint on such a small hill.

The most efficient way to cycle up a hill is to drop into a lower gear as you climb, keeping your pedaling cadence nearly constant on the flat and the slope.

You’re right, if you tried to start the car or truck in the same gear as the one in which they can do 80mph. That’s why cars and trucks (and bikes) have gearboxes). I know you know this, but I couldn’t let such an obvious nit go unpicked.

It’ll also depend on the gearing of your bike. For any given gearing, there is some maximum slope such that you can’t maintain speed for any slope greater than that. If you’ve got a fixed-gear bike, then building up speed beforehand might be the only way you could possibly get up the hill at all.

On the other hand, if your bike has an extreme low gear, then it might be more efficient to downshift and just crawl your way up to the top. The gearing takes care of ensuring that your muscles are working at maximum efficiency, and the low speed reduces losses from air resistance and rolling friction.

From experience, using a very low gear to go up a hill is still a lot of work, even if I’m pressing the pedals just as hard as if I were traveling faster in a higher gear on flat pavement. I’d guess it’s because I’m exerting more energy staying upright; leaning farther right and left, and turning more sharply to counter that. There’s also less cooling from the passing air, making me heat up more.

That’s why I just switch to higher gear, usually to 6th (out of 7), stand up and using the strength of all my four limbs brute force the hill up at a speed the average Sunday cyclist would come down the same slope. It is a bit tiring but minimizes the time spent doing the uphill struggle.

I’m not sure how it all works out in the actual biological level of my body but the short, sharp burst of work certainly feels less annoying than doing it the slow but sure way. Usually I switch back to 4th gear and sit down at the top to get my breathing back to normal levels.

That will work on a short hill but on a climb of any length you will rapidly run out of energy and “blow up”. You will find yourself searching for your smallest gear and giving it everything you have just to turn the pedals over. Meanwhile the slow and sure “spinner” will pedal past you with a nice rhythm feeling not much different from if they were riding on the flat (just going slower.)

How slow are you going? I think you would have to be going very slowly indeed for the process of staying upright to actually use any significant energy. Even at my slowest, which is about 8 kph, I don’t find staying upright to be the major issue, it’s normally just the pure gradient of the climb. I do find that there is a happy medium for hill climbing and sometimes I feel like I’m using more energy going slowly than if I went at my natural pace. I think it just comes down to spinning too low a gear being just as inefficient as trying to grind out a high gear.

This is definitely a factor for me.

Thank you all for your input. Very Interesting!

I suck at climbing hills so I am looking to make it as easy as possible :slight_smile:

on my mountain bike, i do both. i sprint and let the momentum carry me as far as possible (and catching my breath) before i stand on the bike and “walk” up the rest of the way on the 6th or 7th gear. i don’t know if that’s the easiest way but i cannot stand pedalling with the usual cadence and taking forever to crest the hill.

If you suck at riding up hills, lose weight and get stronger! Other than that, if you want to ride lots of hills or long hills in one ride, go up at a sustainable cadence and speed. Personally I like to have a cadence around 90 rpm and my height rate somewhere around 165 bpm which is about 90% of my max. With those numbers I can climb hills all day and it doesn’t “take forever to crest the hill”. For me it is both the fastest way to get up a hill and the most sustainable way. If it is a short hill of only say half a kilometer then I might stand and sprint up, but in so doing I’m burning energy that I don’t get back over the ride and I can only do it a certain number of times. If, having spun up the hill in a sustainable way, I find myself close to the top and feeling good, then I might sprint the rest of the way.

exactly what kind of hill are we talking about here? i’m picturing at worst a 45° incline of at most 30m. or maybe i am just impatient, but i don’t see how anyone would “blow up” over such a short distance.

I doubt you’ve ever pedaled up a 45 degree incline. A 20 degree incline looks and feels like it’s 45 degrees. 45 degrees is killer and you’d almost never find it on a paved road. No doubt mountain bikers do it for short runs.

The best bet is to go at the highest comfortable crusing speed, slow enough that you’re not wasting all your energy to fight air resistance (at 30 mph, nearly all the energy is going into moving the air. At 15 mph, only a small portion is.

When you hit the hill, continue pedaling and downshift as needed to keep your rhythm steady.

BTW, I learned the hard way that it’s bad for your knees to push against a heavy load, especially when it’s cool or cold. I was 25 and it took 3 months for my knees to recover from a 1 hour ride (where I thought I could push through the pain … bad plan). It’s a lot better for your body to spin than to grind. Of course, there’s a lot of variation, and some can handle a lot more grinding than others. But watch the Tour De France guys. They don’t grind much, and they spin pretty fast. I bet they have a clue.

The steepest paved roads in the world are about 20 degrees.

The steepest road in the World is 19° or 35% which is Baldwin Street, in Dunedin, New Zealand. I ‘climbed’ it earlier this year and it’s one of those streets you would jump off your bike and walk up, no way the energy involved in cycling up there would be efficient or enjoyable unless you liked that type of thing.

Here is a photo of the street, not sure if linking that is okay so Mods please delete if not.

No, you won’t have any problems over such a short distance, but the fact that grinding your way up a long hill is not sustainable is a hint that it is not as efficient as spinning your way up. On a short hill if you want to go up it fast then you can sprint up with no problems but if you want to go up efficiently, maintaining your cruise speed then downshifting as required to maintain your cadence as mentioned above would be more efficient.

What nonsense.

Firstly, while you are probably correct that if you are struggling you are probably using your muscles inefficiently, as a consequence of the vast majority of bikes using gears, this is probably not a consideration.

Secondly, as others have pointed out, speed is inherently inefficient because as speed builds, air resistance builds as a square. So building up a heap of speed to get up a hill is inherently inefficient compared to spinning your way up slowly.

Thirdly your example using a skateramp appears to completely confuse efficiency and effectiveness. Building up speed to get up a hill so steep that one’s limits of strength and friction won’t allow you to get up any other way is certainly more effective, but on anything that is not too steep to spin up it is no more effective, and substantially less efficient due to air resistance. And the vast, vast majority of paved road hills can be spun up on most modern bikes.

Fourthly as to the “won’t start” thing, again, it is a matter of traction and starting torque, not efficiency. If you had a bulldozer with enough power to lift its own weight and magic sticky tracks, the most efficient way to get it up an 80% slope would be to start it at the bottom and drive it to the top, slowly. Giving it a run up might be faster, but would just burn energy on fighting air and mechanical resistance maintaining speed.

For a short hill, it hardly matters what strategy one uses. For a long one, the trade-off is that taking elevation is a function of distance, while resisting gravity is a function of time. An aggressive pedalist will expend less total energy, whereas a less aggressive one (who gears down) will have a lower load at any given time during the climb, but it’ll take longer. Personally, I prefer the latter strategy, recognizing that the total energy expenditure is greater. Others, of course, take the opposite approach.

The ideal answer for efficiency is that you should be geared so that you are making as consistent an effort (be it by heart rate or percieved effort) throughout the downhill and uphill portions as possible. That will be fast on the flat and slower going up

As a machine we work more efficiently at consistent moderate effort than at high intensity. Sprints are not efficient.

If the hill is so steep that the same consistent effort will not get you up there (despite being the lowest gear you are having to throw in your upper body, lower your cadence, and are having an increased heart rate) then minimizing that difference in effort by increasing the effort some on the preceding flat to gain momentum makes sense. The goal again though is to minimze the variation about the mean of your effort intensity.