I don't know too much about the mixte or step-through style of frames. My girlfriend is currently looking for a road bike that become a single speed, but she likes the mixte style of bike. Are there are advantages or disadvantages when using that style of frame over a more traditional frame aside from convenience of not kicking your leg over the saddle?

She's enjoying sprinting around in the drops on the trails lately and I don't want to invest heavily into a mixte if she'd be better off with a "men's" road bike.

Define "better off" - there are basically two things: if all other things are equal, a mixte frame will be slightly less stiff than a diamond frame and two, all things are rarely equal as the vast majority of mixte frames are hi-ten steel and the "ladies'" equivalent of the entry level mens' bike. There are a few exceptions to that but not that many. But is your girlfriend a strong enough rider to notice a bit of extra flex in the frame? Does she push the bike that hard? If high performance is an important criterium then go with the diamond frame. But if she's looking for a nice comfortable bike to ride the local MUP than a mixte is fine.

I would echo just about everything here. If your girlfriend is looking for a traditional mixte (parallel top-tubes) the latest is the Buena Vista from Soma (~$500 frameset). Or, try tracking down a solid chromoly mid-80's Japanese mixte. I also hear that Peugeot mixtes from the 80's using "HLE" tubing are decent. Although I've never ridden one.

Mixte's look cool, very cool. To me though, they don't look right with drop bars - can't understand that at all.

And yes, the old Peugeots (and Motobecanes) are very nice. The Japanese ones will be easier to find parts for.

If your GF like mixtes by all means she should have one! I love my Motobecane. The Soma mixte has a very classic look...

Yes! Another reason to show off my wife's mixte!







48-20 drivetrain is dead silent.

I have died and gone to Hosta heaven

What kind of bars and crank?

Really? I kinda of like the Rando bars on my wife's Mixte. She seems ok with them but I may put some doves on it or a straight bar. Depends on what we decide to do with it.
Its a project bike and needs rims. I have toyed with the idea of making is a single or fixed and build a Schwinn World sport project bike I have set it up the same and paint them to match.

This one is a Mang Alloy frame with Suntour ARX bits and Diacompe 500 brakes.

The Pink/watermelon mixte consists of: Sugino RD cranks and bottom bracket 103mm square taper. Nitto North Road handlebars. Mavic Open Sport rims, Formula hubs, DT spokes, ACS freewheel, Dia Compe 750 brakes, Pyramid fork, Tektro levers, Shimano pedals, Peugeot Iseran frame, 24mm seatpost, Brooks saddle, Acorn saddle bag, unknown stem, Ritchie headset, SRAM chain, Pasela tires with reflective strip.

LINK

I find it difficult to hold the bike up and put my foot over the double top tubes on most mixtes, so I end up throwing my leg over the saddle. My wife does the same even though I bought her mixte due to an issue with her hip. She really needs a step through frame.

Mixtes do flex a lot. Grab one by the stem and push sideways on the saddle and you'll see what I mean.