# How to calculate the output rotational speed?

**Sommaire de notre article**

- How to calculate the output rotational speed?
- How to calculate the speed of a wheel?
- Which crown for a pinion of 13?
- Why change the gearbox output sprocket?
- How to calculate gear ratio?
- How to measure the rotational speed of a wheel?
- How to calculate the number of sprocket teeth?
- What is the difference between a left gear and a gear ratio?
- How big is a gear?
- What is the difference between a concurrent gear and a transmission ratio?
- What is the pressure of a gear?

### How to calculate the output rotational speed?

It is defined by the ratio between the **speed** entrance and that of **exit**. It is therefore easy to **calculate speed** of **exit** (n2) if we know the **speed** input (n1) and the gearbox index (i). Just divide the **speed** of **exit** by the index.

### How to calculate the speed of a wheel?

The frequency is the number of revolutions per second, i.e. 1 revolution/s or 1 Hz. in one minute the **wheel** does 60 rounds; in 20 minutes **wheel** does 60* turns.

### Which crown for a pinion of 13?

On our CBRs, we cannot put smaller than one **pinion of 13** teeth. We therefore have in our bag **13 sprockets**14 and 15, and **crowns** of 44, 46 and 47.

### Why change the gearbox output sprocket?

2 reasons can lead you to dismantle a **pinion** : Replace a **pinion** original worn by a standard model, Exchange a **pinion** against a model of different size to play on the performance of your mécaboite.

### How to calculate gear ratio?

For **calculate** the **gearing down**, just make the ratio between the two gears engaged in a gear. Here, the diagram indicates that the first gear is engaged with a 16 pinion for the primary shaft and a 38 pinion on the secondary.

### How to measure the rotational speed of a wheel?

A cyclometer allows **measure speed** linear v of the **wheel**. A tachometer allows **measure** the frequency of **spin** n of the **wheel**.

### How to calculate the number of sprocket teeth?

the diameter of the pitch circle (or pitch diameter) divided by the **Number of teeth** : m = d/z; the height of **teeth** divided by 2.25: m = h/2.25.

### What is the difference between a left gear and a gear ratio?

Left gear: gear whose axes are neither parallel nor concurrent with rotation. Transmission ratio (R): ratio of the output angular speed to the input speed, i.e. also the number of teeth of the input – called driving – over the number of teeth of the output – called driven – of the gear .

### How big is a gear?

The smallest have gears of a few tens of nanometers in diameter, the record being a gear consisting of two six-tooth gears 1 nm in diameter.

### What is the difference between a concurrent gear and a transmission ratio?

Competing gear: gears whose axes have a point of intersection. Transmission ratio (R): ratio of the output angular speed to the input speed, i.e. also the number of teeth of the input – called driving – over the number of teeth of the output – called driven – of the gear .

### What is the pressure of a gear?

In the case of the classic gear, and more particularly of the standard gears, the base circles are brought together so that the interior straight line forms a pressure angle α with the perpendicular to the straight line which passes through the axes. According to the standard, α is 20° or 14.5° for old gears.