Running and exercising

I wear a v4 holy trainer. For a long time I took it off before running but decided I'd try wearing it for a run and it felt no different; I think I may have even gotten a PB! I have worn it a handful of times running and one occasion I had the smallest graze on the gland of my penis (through the slit of the cage) from the friction of my running wear. I haven't had the issue since and have considered putting tape over the slit, or vaseline to prevent it occurring again.
It's worth mentioning however that I do short distance running (5km) and have never tried long distance.

One thing I am not brave enough to do is try cycling whilst wearing it. However, from the little research I have done, people say that is also fine.