All available race results Willum Nielsen
| Date | Race | Rank |
| 17/07 | Sjælland Rundt | 3 |
Rider information for 1915
| Rank | 72 |
| Score | 29 |
| Name | Willum NIELSEN |
| Country | Denmark |
| Team | Individual |
| Date | Race | Rank |
| 11/08 | Nordisk Mesterskab | 3 |
Rider information for 1918
| Rank | 93 |
| Score | 29 |
| Name | Willum NIELSEN |
| Country | Denmark |
| Team | Individual |
| Date | Race | Rank |
| 04/08 | World Championships Time Trial (Ama) | 2 |
Rider information for 1921
| Rank | 170 |
| Score | 109 |
| Name | Willum NIELSEN |
| Country | Denmark |
| Team | Individual |