The term monster bike refers to constructions relatively similar to bicycles but different than ordinary bikes. A monster bike has more or less the same elements as theirs: chain, wheels, handlebars and so on. Some of them are modified on purpose just to show off or to create a sense of illusion or amusement when people see them. I wrote about the tall bike ridden by Quico and this is a kind of monster bike. One only needs imagination, the appropriate parts and perhaps a blowtorch in order to create monster bikes such as the following.
More elaborated monster bikes look like this: