This is my personal standard for figuring out whether or not a bike is a good size/weight for you
- Can you plant both feet on the ground firmly enough to move the bike around? As an example, if you park on a slanted driveway, would you be able to press your feet down squarely enough to scoot the bike back up the driveway if you couldn’t turn around?
- If you have one foot flat on the ground, can the other foot at least touch the ground?
- If you have one foot flat on the ground, is the bike leaning at enough of an angle that it’s difficult for you to pull it upright again? If your bike started to tip over at a low speed (such as going around a tight corner) and you had to slam one foot down to stabilize it, would it be tilted too much for you to get it upright again without letting it drop and picking it up?
- Can you plant both feet on the ground firmly enough to hold the bike in place without using the breaks? If you were stopped on an incline and put the bike in neutral, would you be able to hold it in place with your legs in the event you had to use your hands for something?
For the sake of simplicity those are all eventualities that are good to plan for. If you’re experienced at riding you might not prioritize these things, but if you’re experienced at riding you’re probably not looking online for advice on picking a bike that’s the right size for you. These are just things that I personally think make something safe and comfortable to ride with the confidence that you can manhandle it upright if you need to.