Willi Knabenhans turned professional after the 1928 Olympics and briefly rode in the professional peloton, racing in 1929-30. He placed third at the 1929 Swiss Championships in the road race. As an amateur he won the Swiss Championship in the sprint on the track in both 1927 and 1928.
|1928 Summer||22||Amsterdam||Cycling||Men's Sprint||Switzerland||SUI||4 r3/6|
|1928 Summer||22||Amsterdam||Cycling||Switzerland||Round One Repêchage||Heat One||1||QU||14.2|
|1928 Summer||22||Amsterdam||Cycling||Switzerland||Repêchage Final||4|
|1928 Summer||22||Amsterdam||Cycling||Switzerland||Round One||Heat Three||2||at half length|