It's hard to say. There are riders that weave their way through the GGB walkway with grace and aplomb. There are some that put other users of the bridge at risk due to their hurried pace.
I'd say lycra clad riders have made me pucker more times than tourists. But my closest call was with a tourist walking. Just jumped right into my path to get a photo, I was about 4 feet away. Good thing I was beat and just limping along.
Remember folks living car free isn't just a lifestyle it's an attitude.