dossard

noun1

1. •
   A bib attached to the back of a cyclist's shirt that carries the cyclist's race number.

   • [Bernard] Hinault will also be wearing a 51 dossard, the same number with which Luis Ocana, [Bernard] Thevenet, [Eddy] Merckx, and [Jacques] Anquetil pedalled to victory in their first Tour. — 1979