Borrowing or renting a bike? A quick and dirty method to get a simple fit.
A. Get your cycling kit on (or whatever you will be riding the bike with). Especially the shoes. (not sure what shoes or peddles see this).
B. Find a wall or fence that you can hold on with one hand or rest against.
C. Get on the bike. PUT THE HEELS OF YOUR FEET ON THE PEDDLES. Not the balls of your feet which you will be cycling with.
D. Cycle backwards with the heels of your feet on the peddles. Your goal is to extend your leg to the bottom of the peddle stroke so your leg / knee is straight. You want to be able to do this on both sides of your feet and keep your hips square / horizontal.
If your knees do not become straight at the longest point of the peddle stroke increase the height of your saddle.
If your heels dont touch the peddles with square hips bring down the saddle until they do.
It’s a very simple procedure and after two or three attempts you will get the hang of it. Then next time you get a rental bike or borrow a bike spend 10 seconds adjusting the seat hight like this.
If you buy a bike, especially a nice one get a bike fit. Your local bike store can help out do a step up but a professional bike fitter is worth the money if you’re going to be doing a lot of cycling. It will reduce repetitive injury and make the experience more comfortable.