If you are post-prostatectomy, then the activities that I mentioned (bicycle riding and sexual activity) should not affect a PSA level. "Leftover" prostate tissue that was not removed during the prostatectomy ("surgical margins", likely from Extra Prostatic Extension a.k.a. "EPE"), that slowly begins to grow, will be your only source of PSA test value increases, and...very slowly over time, unless your pathology was such that your prostate cancer was deemed an aggressive form, despite your Gleason Score. My Gleason Score was Low Intermediate Risk at 3+4=7 with just 6-10% of cells being "4", but upon post-RP pathology review of my prostate tissue, my cancer was deemed more aggressive with left seminal vesicle invasion, Cribriform glands, EPE, and surgical margins that I mentioned. I went from being what my urologist thought would be a T2 at worst, to being a pT3b with near certainty that my cancer will return "within" five years...it might be this year, next year, two years, etc., but there is no less than a 25% likelihood of it returning. That is the mystery..."where" is it lurking...hanging out...if my prostate, both seminal vesicles, and both vas deferens were removed along with all vasculature that would provide blood supply to any remaining cancer cells. Exasperating...frustrating...and anxiety-ridden. So far, with two post-op PSA levels at 3 months and 6 months, my values have both been < 0.1 ng/ml ("zero"). Being a pT3b feels like I am walking around with a ticking time bomb on my shoulder...waiting...waiting...for it to tap me on the shoulder and say: "I'm baaack, and I'm going to kill you"... BOOM.