I have a case of BHP, meaning my prostate is large. It was the size of a large grapefruit. Now post-surgery it had an apple sized chunk out of the inside.
I still ride a Brooks B17, Professional, Flyer, or a Cambium C19 or C17.
My Doctor said that he knows of no reason for prostate troubles due to bicycles.
A good bike fit helps to make sure you are not over stretching your leg.
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Cambodia bikes, Bridgestone SRAM 2 speed, 2012 Fuji Stratos...