Vincele714

I wanted to convert my bike to a Dutch style upright for city commuting. I’m guessing the only things I need to change are the seat and handle bars right?

hokiefyd 

At the minimum, the mechanical changes would include a different handlebar and different brake levers. You'll most likely be looking at handlebars with a 25.4mm clamp size and I think your current stem is probably a 25.4mm as well (I think the older road bars used this size). If your drop bar has a larger clamp diameter, then you'd need to either change the stem or get a thin shim that would allow it to clamp a bar with a 25.4mm clamp size. You'll also need flat bar style brake levers for the brakes. You'll need short-pull brake levers (those designed for use with caliper or cantilever brakes). These will have a 22.2mm clamp size, which is the same as nearly all swept-back upright bars (but do check the specifics when you buy parts to be sure).

As you note, you'll probably also want to change the seat to something more comfortable for upright riding. You may also want to change the shifters from the downtube location to up on the handlebar. Depending on your specific shifters, you may be able to find handlebar mounts that would allow you to adapt you current shifters for that use. There are also many styles of thumb shifter, bar end shifter, etc. Unless your rear derailleur has been replaced, it's probably not designed for indexed shifting, so newer trigger- or grip-style shifters wouldn't be of use for you (and would not shift correctly). The most common shifter for an application like this is a friction thumb shifter. As I said before, you may be able to adapt your current ones...but there are also many aftermarket and used options available. From new Sunrace SLM10s on the low end to any number of high quality new and used metal body thumb shifters from the likes of Microshift, Shimano, Sunrace, etc.