This is a notion known to many people who cycle – how ever many bikes they have, there’s often a desire for one more!
“It’s adding another bike to your bike collection (number of bikes = N + one new one)”. John_V on BikeForums
Many people only have the money or space for one bike. Others who cycle regularly (not just to work) begin to understand why having more than one bike is useful.
It increases the chance of having a working bike. Tyres have a nasty habit of going down overnight (slow puncture).
A lot of people who start cycling discover they want to cycle more, which often leads to a lighter ‘faster’ bike. This can be for a weekend ride in the country or sport – maybe for audaxing (some people get very keen).
After getting a ‘racing’ bike and maybe a ‘mountain’ bike some people find room in their lives for a load carrying bike (including for children).
There are people who just cycle to work, and may have no interest in bicycles – except as a means of transport. They are unusual but completly normal. Other people find cycling – and ‘collecting’ bikes completely normal!
Many employers take part in the Cycle to Work scheme. This is where employees can buy a bike using “salary sacrifice” – spreading the payments interest free – and also get a tax saving.
This makes N+1 desires easier to deal with!