It's a good thing handlebars are some of the easiest parts to swap on a bicycle, because small variations can make a huge difference in your comfort while riding!

• Upright bars raise your eyeline, and the well-designed ones are super comfortable. Try a "north road" aka "tourist" style one if you haven't, they've been around and very popular since the 19th century. The rise, sweep, and angles of these handlebars differentiate different models. Nitto make a lot of very good ones in their Tokyo factory.
• Flat bars, like those from MTBs, are super wide and let you control the bike well in more conditions, like on twisty trails in the woods. They may be less suitable for confortable all-day riding if you're not used to them.
• Drop bars, the curvy ones for road bikes, are good for going fast in an ærodynamic position, but are also quite comfortable for all-day riding, since they're quite ergonomic when well-set up, and offer a lot of hand positions so you can shift your hands around. Drop bars use different, incompatible brake levers from the other types of handlebars, and usually you can't slide on grips so you'll want to wrap them in some kind of fabric.

We stock shims to adjust this, but it's best if you make sure your stem and handlebar clamp diameter match before buying. Common sizes are 25.4mm, 26.0mm, and 31.8mm.