Pretend instead of “serious” they said “frobnozz”. You’re not a frobnozz cyclist unless you can do a handstand on your handlebars! How absolutely un-frobnozz can you get??

There’s a tendency to ascribe value to words like “serious” but it’s a temptation, nothing more. Who cares that some bozo thinks “serious” drivers drive manual transmission cars, or ride bikes in a particular way.