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Cyclecomputer Calibration Group E
Original article: https://www.sheldonbrown.com/cyclecomp_e.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.
CatEye Solar (miles); Paramount Series 8, 10 (miles); Sachs Huret (miles); Sigma BC 400 (miles); BC 500 (miles), BC 401 (miles); BC 500 (miles); BC 600 (miles); BC 700 (miles); BC 800 (miles); BC 1100; BC 1200+ (miles); BC 1400 (miles); BC 1600 (miles); Vetta Cycle Computer (miles)
Circumference in millimeters/1.6093
See explanation if you are measuring using a rollout test. This calibration number is different from the one for kilometers for most of these cyclocomputers..
| 700 X 44 | 1382 |
| 700 X 38 | 1355 |
| 700 X 35 | 1347 |
| 700 X 32 | 1339 |
| 700 X 28 | 1327 |
| 700 X 25 | 1308 |
| 700 X 23 | 1302 |
| 700 X 20 | 1296 |
| 27 X 1 3/8 | 1349 |
| 27 X 1 1/4 | 1343 |
| 27 X 1 1/8 | 1339 |
| 27 X 1 | 1333 |
| 26 X 2.125 | 1286 |
| 26 X 1.9 | 1276 |
| 26 X 1.5 | 1234 |
| 26 X 1.25 | 1213 |
| 26 X 1.0 (559 mm) | 1189 |
| 26 x 1 (650C) | 1213 |
| Wide 700C Tubular | 1316 |
| Narrow 700C Tubular | 1308 |
| 26 X 1 3/8 | 1288 |
| 24 | 1191 |
| 24 x 1 | 1089 |
| 20 X 1.75 (406) | 927 |
| 20 X 1 1/4 (451) | 1005 |
| 17 x 1 1/4 | 838 |
| 16 x 1 3/8 | 797 |
These computers don't adjust their internal math -- instead, you change the calibration number. A mile is 1.609344 kilometers, and the calibration number for miles is the tire circumference divided by 1.609344. You can measure the tire circumference with a rollout test, then do the division.
The manual for the Vetta Cycle computer gives the calibration number for miles as 3.9042 times the radius of the wheel. This is the same as the circumference divided by 1.609344.
