I imagine what you normally do to prevent poop particles should be fine. Also I believe most people wear underwear under bike shorts? I cycle almost daily but just wear regular clothes or gym clothes so not entirely sure with padded bike shorts.
Also, having grown up all my life with bidets and “bum guns”, it never hurts to clean down there with some water and soap anyway.
Now I’m kinda weirded out that all the people I see in bike shorts are going commando under there…
Edit: Well there you go. Suppose its no different than skin tight swim shorts.