The ornamental design for a bicycletrainingsupport, as shown and described.
FIG. 1 is a top front isometric view of a bicycle training support showing my new design;
FIG. 2 is a bottom rear isometric view of the bicycle training support of FIG. 1; and,
FIG. 3 is a top front isometric view of the bicycle training support, with a cyclist and bicycle depicted by broken lines.
The broken line showing of the cyclist and bicycle is provided for purposes of environment and form no part of the claimed design. The pair of handle bars are depicted in broken line form because they depict a portion of the bicycle training support that is unclaimed.