Gerdemann, who was unable to secure a professional contract last season, finished fourth in the 149km first stage of the Tropicale Amissa Bongo from Bitam, in northern Gabon, to Ebolowa, in Cameroon.
Spaniard Luis Leon Sanchez of the Caja Rural team won the stage ahead of countryman Egoitz Garcias.
Gerdemann and Rwandan team-mate Adrien Niyonshuti formed part of an early 21-man breakaway after only 15km, opening a lead of more than 10 minutes on the rest of the field.
The duo held on for most of the stage but were unable to give MTN Qhubeka a podium finish on day one of their season opener, with Gerdemann narrowing missing out on third place.
Today’s 120km second stage is the shortest leg of the seven-day race.