Backstory: We've been biking at the same park, Govalle Park, training for an upcoming ironman. Every weekend we load our bikes and trek to the park, unload and have to reload them before coming back home. It's a repetitive task that gets annoying.  

The Idea: Short and long term storage for bicycles.

Deep Dive: You would build out a simple, secure facility for riders to store their bikes. You could go two routes with this: staffed or unstaffed. By having a staff you could sell additional items like sport drinks and water but unstaffed would limit your overhead and risk. 

Given that bicycles take up ~12sq ft of space (6x2ft), you'll have to find a space that works for rent vs fees for that amount of space. An option is to have double tiered storage, two levels of bike racks.

Validation: Some places in the Netherlands have storage facilities at train stations for bikes.

Monetization: You would charge a monthly or daily fee for customers to store their bikes.

Steps to Launch: I would start with this being unstaffed and pre-sell some spots. Once you have enough sales then buy and install a bike locker. You can try to find a space for the locker at either a park or highly trafficked corporate office park.