Firstly, i will sketch the one for which i am 'looking at' in my imagination. Initially a rough sketch will do to get complete idea.
Secondly, i will do modelling of my bike. Before designing comes Modelling. Nowadays modelling of bike is done by use of computer softwares. This provides idea about space available with engineers to design any component.
Thirdly, i will go for designing my bike. Designing is a complex synthesis and analysing process of forces and stresses on any component. Designing of each and every component should be done according to the Model. Engineer has to import the ready model of component from modelling software to designing/ analysing software.
Fourthly, designed components cannot put into production without testing. For testing, one has to produced 3-4 designed bikes. Make produced bike to test on roads.
Fifthly, i will go for production of my bike after testing the same. Joining each and every component will be the task in production. This will be done to get a bike to ride.
I got to see one bike which was for more than 7 seaters. I may design a bike with 'n'number of seats. Its upto readers for how many to include on my bike.