Cycling's effect On The Bladder?
You likely won't find anything conclusive, because the required testing would be so varied.  

Anything done poorly can cause problems.  Any sport lends itself to an increased chance for injury.  However, proper technique and equipment generally alleviates some, if not most of that risk.  

In cycling, proper hygiene, attire, technique and bike fit are all important.  Keeping your skin clean (before and after rides).  During rides (especially longer rides) chamois cream of some sort can help immensely.  Bike shorts are made for a reason: they work.  They should also be clean, however.  Other attire is also important.  Overdressing and sweating yourself out only creates a breeding ground for bacteria.  Remember body odor varies from person to person, but is largely caused by the flora on the skin.  No reason to build it a Disneyland unnecessarily.

A properly fitting seat and bike will minimize friction and irritation.  These factors can cause surface skin damage which then leads to infection (saddle sores, etc) after the skin begins to break down.

If you are referring to bladder infections, I think it would be a long road with a lot of ignorance to get there.  While females are generally more prone to UTIs, and cycling could increase the risk of those, the steps necessary to reduce the risk are quite easy and really part of basic hygiene.  Getting a UTI and then ignoring it long enough for it to hit the bladder would require an additional step of disregard.