--- title: Riding a bike: why it stays up — a lesson of Mova's school · trees and pragmatics description: «Riding a bike: why it stays up», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: A bike stays up not by holding still but by steering: whenever it starts to tip, you turn the front wheel a little into the lean and bring --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/) / Riding a bike: why it stays up # Riding a bike: why it stays up Lesson 9 of the physics course of Mova's primary school: 18 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/physics/9-riding-a-bike/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/0/) — A bike stays up not by holding still but by steering: whenever it starts to tip, you turn the front wheel a little into the lean and bring the wheels back under you. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/1/) — That is why a moving bike balances and a still one falls over, and why riding very slowly feels wobbly. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/2/) — Bikes are also built to help: the shape of the front fork (the two arms holding the front wheel) makes the front wheel turn into a lean by itself, so a riderless bike pushed along rolls a long way upright. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/3/) — Stabilisers stop the bike tipping, so you never learn this steering, which is why balance bikes with no pedals teach children faster. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/4/) — Gears, brakes and tyres follow simple rules too: a low gear makes hills easy, and slamming on only the front brake can throw you over the handlebars. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/5/) — A moving bike stays up because the rider steers into any lean and brings the wheels back under the centre of gravity. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/6/) — The faster you go, the smaller the steering needed, so very slow riding is wobbly. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/7/) — A riderless bike pushed along can roll a long way upright, because the shape and weight of the bike make it steer into a lean by itself. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/8/) — Scientists found that no single magic trick keeps a bike up; it is the bike's shape and weight together. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/9/) — Stabilisers stop the bike tipping, so children never practise steering into a lean, while balance bikes teach that steering first. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/10/) — Cyclists lean into a corner to balance the sideways push of the ground on their tyres; turning sharply without leaning makes you fall outwards, and leaning hard while going very slowly tips you over inwards. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/11/) — A low gear turns the wheel less for each turn of the pedals, so you push more gently but pedal more times up a hill; a high gear turns the wheel more for each turn, which is good for going fast on the flat. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/12/) — If you squeeze only the front brake hard, the front wheel stops but your body keeps going, so use both brakes and sit back on steep hills. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/13/) — Big wheels roll over bumps easily, and thin, smooth tyres rub the road less. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/14/) — Mountain bikes have wide, knobbly tyres for grip on mud, and road bikes have thin, smooth ones for speed. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/15/) — A bike pump gets warm because squashing air quickly warms it, and a pumped tyre is hard because many air molecules (tiny bits of air) push on the rubber. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/16/) — If a front wheel starts to wobble at high speed downhill, grip lightly, press a knee on the frame and slow down gently. - [17](https://md.mova.elamur.ai/free/en/corpora/school/physics/9-riding-a-bike/17/) — Riding no-hands works by leaning your body, but only at a decent speed on a smooth road, and never in traffic. - ← previous: [Balance: the centre of gravity](https://md.mova.elamur.ai/free/en/corpora/school/physics/8-balance-the-centre-of-gravity/) - next →: [Swings and pendulums](https://md.mova.elamur.ai/free/en/corpora/school/physics/10-swings-and-pendulums/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)