WikiPedalia is not endorsed or affiliated with the Wikimedia Foundation.
Cyclecomputer Calibration Group D
Original article: https://www.sheldonbrown.com/cyclecomp_d.html on sheldonbrown.com
- Reproduced with the permission of John Allen and Harriet Fell — all rights reserved. The version on sheldonbrown.com is authoritative.
- Mirrored: 2026-10-05 · Last update of the original: see original
If the model name is highlighted, clicking on it will take you to detailed setting instructions. Otherwise, look up the computer in the cyclecomputer database.
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.
