actually the OP asked,"Is there a comfortable way to carry while on the bike?" and also said, "Carrying all my firearms to shoot would be ridiculously undoable on a bicycle." he also spoke about a concealed carry permit, something not required to carry a gun to a range, at least here in texas. so while he may not need or want to "bust a cap in someone's ass", i do believe he was asking about carrying a concealed weapon for self-defense. and yeah, a 50 cal. would be overkill... but a small .380 can fit reasonably in a handlebar bag or even the front or rear pocket of a pair of baggy shorts. keep in mind that here in texas the gun must be concealed, i have no idea what it's like where you live. you can also carry a concealed firearm in your personal car without a chl license here in texas.
i've had a permit for some time as my job sometime requires me to be in places that self-defense might prove necessary, otherwise i don't carry a gun. it's often awkward for me to be at gun shops as usually the politics there are about as opposite from mine as is possible. i'm as liberal as they come. i also carry a gun occasionally.