Where N is the number of bikes you currently own. Such an equation is sacrilege in the bike community that commonly touts N+1. I’ve heard that the industry has figured out that unless they get more women riding bikes, the total number of bikers will stagnate and even decline. So to sell more bikes, they’ve got to sell more bikes to the same number of riders.
We now have some amazing bike that are designed to kill it in specific applications. Aero road bikes, comfort road bikes, lightweight road bikes, time trial bikes, gravel bikes. Cross country bikes, trail bikes, enduro bikes, bike park bikes, downhill bikes. Fat bikes, plus bikes.
Listing all of those categories is sure to point out the gaps in your stable, and you’re probably about to open a bunch of browser tabs looking at the different categories and have already budgeted in the costs.
But think about the variety of the trails you enjoy riding or see yourself riding. How much time do you really have to ride? What if instead of buying a cross country bike and an enduro bike, you got a really nice trail bike with carbon wheels and dropper post. Something that weighed close to the cross country bike, but only gave up a small bit of capability to the enduro bike. The extra suspension would make the bike faster on all singletrack, climbs included. What about a cyclocross bike that could fit 42mm tires? The bike would be capable on everything from roads to rocky doubletrack and easy singletrack. Not impossible. Like a 29er hardtail with cyclocross geometry and a narrow road bike bottom bracket. Discs and cyclocross geometry would limit it for road racing.