Jansma started with international bobsleigh competitions in the 2002 and was not yet part of Arend Glas's team that participated at the 2002 Winter Olympics in Salt Lake City.
However, Jansma developed himself to become Glas's main compatriot in the years to follow in both the 2-bob as the 4-bob.
In January 2006 Jansma qualified himself in the team of that several weeks earlier secured its qualification for the 2006 Winter Olympics in Turin.
At the qualification play-off (named bob-off) held in Oberhof, Germany, he ended up in first position claiming his seat in both possible bobs.
His best finish at the FIBT World Championships was seventh in the four-man event at Lake Placid, New York, in 2009.