Why it is easier to get off the bike and walk up the steep road with it than riding it all the way up?
In: Physics
A bike left stationary on the hill would roll downwards as it is being pulled by gravity.
You are resistant to this pull because you are able to adjust your body weight and use friction to your advantage to keep yourself still on a slope.
While on a bike, you lose that advantage to keep still and are fighting against gravity as the bike normally would.
It doesn’t have to be.
The main reason cycling uphill can be harder is if you don’t have a low enough gear on your bike. In a high gear, it may take too much effort to push the pedals around even once. It’s especially difficult when you hit the “dead points” that occur when you’re having to push each pedal over the top of its revolution. Unless your shoes are clipped into the pedals, like you can do on race bikes (in which case you can pull the other pedal up with your other leg), it becomes very hard to generate enough force on the pedals at those points, to keep them moving.
In other words, you have to overcome the pull of gravity. On the flat, the bike does this for you as all the force of gravity goes through the frame and wheels. As you go up an incline, however, some part of that gravitational force is now pulling you down the incline. The steeper the incline, the greater this pull. To keep moving, you have to generate enough force to at least overcome this pull. How much force you have to generate depends not only on the steepness of the incline, but also on the gearing on your bike. A low gearing gives you leverage that allows you to pedal faster while exerting less force. It’s as if you’ve turned the steep climb into a longer, less steep one.
In a low enough gear, you can bike uphill as slowly as you would walk, and at that point biking should be no more effortful than walking – in fact it should be less as biking remains a more efficient method of travel than walking. However, another issue you may encounter is that a bike becomes less stable at low speeds. So if you have to bike very slowly, you may struggle to keep the bike upright, and that can also be a reason why you may have an easier time if you get off the bike.
It would not be very hard to ride your bike uphill if you could put it in the lowest gear and go slow.
The problem is that bikes become unstable at low speeds. It will wobble and you’ll fall. So you need to achieve a certain speed to avoid it wobbling, and reaching that speed uphill is hard. You either need a higher gear and lots of force or a lower gear and lots of leg-motion (many rotations of the pedals). That may be more power than you can produce sustained over many minutes.
When you are walking, you can go as slow as you want and not fall over. You can take as long as you want and use less power over more time.
Because the gearing on your bike is not appropriate for the incline.
Consider how far the bike moves in one revolution of the pedals, to how far you move with one step with each leg. The amount of leg movement is approximately the same but you need to do more work per “step” with the bike because it travels longer and increases more in elevation.
The distance you push the pedal is not that long and work= force * distance means the force you need to apply with your legs is high, it might even be higher than the maximum force you can apply,
If you had gearing that made it possible to bike at the same speed as you walk and move the legs at the same rate it would feel quite similar to walking, the problem is at low speeds it is hard to balance a bike.
The work to go up a hill is to move against gravity and it will be equal so on a bike with to high gearing result in more of work per “step”
The reason this is not a problem on flat ground is there is no work required to keep constant elevation, you just need to overcome friction, drag, and other stuff that slow you down to keep a constant speed. When you walk on flat ground a large portion of the work is to move your legs and then moving them fewer times for the same distance on a bike is an advantage, as long as the force required on the bike is not to high.
If you use a bike with gears you will notice when you change them and try to keep the same speed that at low speed there is not a lot of force on the pedals but lots of work moving the legs quickly. At a high gear, the force gets high. You want around 1 revolution per second this is called the cadence.
There is another way to accomplish almost the same effect as lower gear is to take an alternate path with the bike. Have another road that is longer but will take the same time to bike up as it take to walk up the steep road. Then the work per unit of time = power is equal for both bike and walking, and it is close to equally hard.
This is why it is not uncommon for paths for bikes, wheelchairs prams etc to be a switchback or a long incline and at the same time there is a short path with steps when you walk,
Bikes need to go at a certain speed to stay upright. If you try stopping or going very slow on a bike, it will topple over.
Going uphill takes a lot more effort. Depending on how steep it is, switching to a lower gear can make it much easier to ride your bike up the hill. If it’s so steep that maintaining your speed to stay stable is a struggle, it becomes easier to walk the bike instead.
Walking allows you to go slow and support the bike to prevent it from falling over. That’s really the main reason. There’s no minimum speed when walking. You can even stop and take breaks.
So, when you’re riding a bike up a steep hill, your body has to work extra hard to pedal and keep going. It’s like running uphill with a heavy backpack on!
When you get off the bike and start walking, your legs don’t have to do as much work anymore. You can just take your time and walk slowly, which uses way less energy.
Plus, when you’re riding a bike, you need to balance and steer at the same time. That takes a lot of concentration and makes it harder to control the bike on a steep hill. When you walk, you don’t have to worry about that as much, so you can focus on just making your way up the hill.
So, all together, getting off the bike and walking up a steep road is often easier because it uses less energy and takes some of the pressure off!
Latest Answers