My wife has a mixte lotus bike from the 80's. It has dropped handlebars and she would like to change them to a more upright handlebar. I know i will need new brake levers and a new handlebar. Will i also need a new stem or can i use the existing one? I also have another noob question. Are all handlebars the same size or do they vary by bike. Any suggestions or help would be welcome.

Thanks

Depends. Most upright bars are 25.4 clamp diameter. Her road bars may be either 26.0 or 25.4, but I'd be willing to bet hers are 25.4, so you'd be set, assuming the extension (length) still works.

And the second part - they're all over the place. Clamp sizes of: 25.0mm (old French); 25.4mm (hybrid, some road, also =1"); 26.0mm (many road); 26.4mm (Cinelli); 31.8mm (new road, also = 1 1/8")

BTW welcome to bikeforums Classic and Vintage forum… Sure you can change handlebars on her Mixte. I have changed the handle bars on my Mixte several times. But, yes there are different size handle bars and you want to make sure the type your putting on will fit your stem. One inch is pretty common on older model bikes, but it’s where the bar clamps into the stem that is important.

As far as using the same stem… you can do that as well, or if you don’t like the looks of it, you can purchase other stems. Again just make sure you are getting the same diameter stem as the one you have. The quill type stems usually have the diameter marked on them below the steer tube line. There are several different sizes, some rare, some common, so make sure you get the same size.

You most likely will need new brake levers… Again get the ones sized for your new handlebars. Also most likely you will need to run new brake cables and housings, because of the difference in lever design, and amount of slack you will need to fit the more upright placement of the brake levers on the new handlebars.

It’s not really as difficult as it sounds, unless you have a bike that has off sized, or odd sized components. Best of luck to you, and be sure to post pictures in the "Show us your Mixte" (Sticky thread) thread when you get it all done, or ever before if you wish. Also if you look through that thread it may give you an idea about what type of handlebars a so on you would like to convert to.

My favorite are the Northroads style bars that were popular on English 3 speeds. If you get them off of an old Schwinn or other American bike, they are 1" and work with most Japanese stems. If you get them from an old Raleigh or other English 3 speed they'll be 13/16" and you'll need to cut a piece of shim out of an old beer can to get them to work with the Japanese stem. Actually, it's a lot easier to get some "shim stock" from a mechanic or auto parts place as it's thicker than most beer cans and you'll only need 1 layer.
It's a real nice conversion that I've done to several of my bikes.

Thanks for all the info.

Is there an online site to get what i need or am i better just to go to LBS?

I'll get some pictures up when i finish. I also have a nishiki international ole that i ride.

You can use exsisting brake levers on an alloy mustache bar-look sweet with bar tape.

https://www.velo-orange.com/haandst.html

There are some nice options on this site. Most likely you have a 25.4 clamp on your stem so if you select a bar that size it will work. If you have a caliper double check that before you order. If you go that route your existing brake levers will also most likely work, although finding the correct placement on the bar takes a bit of trial and error.

I have a set of the Porteur bars on a bike with road levers mounted on the front and I like them a lot.

You wanna trade my '72 Schwinn Suburban handlebar for your wife's drop bar? I'm looking to do just the opposite...



Just a thought...