Although exercise-induced hematuria is a well known finding in long distance running, it is extremely rare in cycling. We describe a case of gross atraumatic hematuria after mountainbiking. The only pathologic finding in our patient was a small hyperemic zone in the bladder mucosa suggesting a local traumatic origin due to repeated contact of the flaccid bladder wall against the bladder base. This in contrast with the renal origin commonly seen in marathon runners. It is a benign hematuria that usually resolves within a day without specific treatment. The best treatment is prevention by means of good bladder filling. Neoplasm of the urothelium should be ruled out in differential diagnosis.