This is mostly a height adjustment, but there is a small amount of movement possible forward and back. Most new cyclists leave their saddles too low, probably to make it easiest to get their feet on the ground quickly. The trouble is that this is not the most powerful way to bike. You work harder and can hurt your back, tire out your legs, etc.
There are plenty of mathematical optimizations to calculate your best saddle height, but most people just approximate it. Here's a quick checklist to get you close to your ideal position:
- Your saddle should be completely level. If anything, the pros say to have it slightly nose-up, but I say that's no good, just go for level.
- With one pedal at the very bottom of your stroke (6 o'clock) and your heel on the pedal, your knee should be just at the bent side of straight. No reaching for the pedal, but still almost fully extended.
That's it! It's easy and will make a huge difference. Note, you may find you want to raise your handlebars once you raise your saddle. That's a subject for another post.
Photo from carfreedays