Bum bike 

Bum bike is any sort of bicycle that's been modified with a small internal combustion engine kit to act as crude but effective moped. They are usually unregulated in most areas.
They are usually operated by a the homeless or a junky who doesn't have a car or motorcycle. This is done usually with a stolen bike and used as a means to get around town quickly while out commiting crime. They are usually very loud since they are use a two stroke motor. When one hears the sound of droning two cycle engine you know the junkies coming around to steal anything that's not nailed down.

Hey Jim do you hear that noise ?!

Jim; yeah it sounds like a bum bike, I better go lock my shit up before it gets stolen

Hey, who's riding that noisey ass Moped?! Oh that's earl, he lost his license when he got a DUI so he made a bum bike so he can get to work.

Bum bike by Anton H April 9, 2025

Bum Bike 

A Bum Bike is any sort of bicycle that has been modified with a 2 stroke engine kit. These bikes are operated by a variety of people including the homeless population who has taken a liking to this quick and cheap form of transportation.
They are great for getting around town if you don't have a driver's license, the kits can be found for less than 200$. It's not uncommon to a see a bum or a junky ripping around on one with a few bags of soda cans and some stolen goods.

Hey Joe you better lock your tool shed I heard a bum bike zip by!

What's that sound !? Oh shit it's a bum bike! The junkies are out to steal catalytic converters again.

Bum Bike by Anton H September 26, 2025

Bike-Bum 

When you cycle on a bicycle that has a REALLY hard and uncomfortable saddle, you'll be left with an annoying pain your backside that you will only feel when you sit on something, even the comfiest seat will hurt thanks to this hidden pain in your bottom.

It takes roughly 24 hours of not riding on that saddle again for it to go away. Depending on how loing you were cycling initially.

Dude #1: Why are you sitting so weird? You're on the single comfiest couch in all existence!

Dude #2: Got Bike-Bum. Even this heavenly sofa feels sore thanks to that cursed hard saddle!

Dude #1: 'Bummer!'

Bike-Bum by Big Red Musey November 6, 2010