## Cyclecomputer Calibration Group D

#### If the model name is highlighted, clicking on it will take you to detailed setting instructions.

Ciclomaster models except CM-37, which uses group C

Magura Velotronic Easy: multiply these values by 2 for km, or by 1.243 for miles.

### The setting is the tire's radius in millimeters

This can't be measured directly: if doing a rollout test, divide the result by 6.283. See further notes by John Allen if doing a rollout test.

### Radius in millimeters

700 X 44 |
354 |

700 X 38 |
347 |

700 X 35 |
345 |

700 X 32 |
342 |

700 X 28 |
336 |

700 X 25 |
335 |

700 X 23 |
333 |

700 X 20 |
332 |

27 X 1 3/8 |
345 |

27 X 1 1/4 |
343 |

27 X 1 1/8 |
342 |

27 X 1 |
340 |

26 X 2.125 |
330 |

26 X 1.9 |
324 |

26 X 1.5 |
312 |

26 X 1.25 |
311 |

26 X 1.0 (559 mm) |
305 |

26 x 1 (650C) |
311 |

Wide 700 C Tubular |
338 |

Narrow 700C Tubular |
335 |

26 X 1 3/8 |
330 |

24 |
305 |

24 x 1 |
279 |

20 X 1.75 (406) |
254 |

20 X 1 1/4 (451) |
257 |

17 x 1 1/4 |
211 |

16 x 1 3/8 |
204 |

If using a rollout test for greater accuracy, divide the result by 6.2832 (that is, divide by 2 * π). If you are using a calculator, it's easier and more accurate to use the π button!

For the Velotronic Easy, divide by 3.142 (or π) and also do the multiplication for miles. The *exact* multiplication factor for miles is 2/1.609344.

If you would like to make a link or bookmark to this page, the URL is:

http://sheldonbrown.com/cyclecomp_d.html

Last Updated: by Harriet Fell