650 wheels

650 wheels were THE THING for tri bikes back in the day.

Nowadays, they've discovered that there isn't really any huge advantages or disadvantages while riding. You usually find them now on S and XS frames, simply because they fit the bike and rider better.

I ride them (2002 Fuji Aloha). Only complaint? If you need a tire or tube on short notice, you'll have trouble finding them. That said, I've got a big box of tubes and two spare tires on hand. And I found cheap used race wheels!

You can use a 700c if you're in need of a tube and it's your only option  

I don't know enough about the specific geometry of this bike, or you preferred riding position, but at 5'10", I prefer (nay, DEMAND!) 650's on my tri bike. I like to ride steep, and the only way to get the chainstays short enough to keep the weight balance properly on the rear wheel is to use 650s (or have a ridiculously long front-center).

In a TT/Tri, there really are no advantages to 650's over 700's. I have both, have ridden both extensively, and really find no performance or comfort difference between them. Gearing on a 650 bike as opposed to a 700 is not rocket science -- think 2 teeth more on the 650's chainrings over the 700 (a 52 on a 650 will be pretty much the same as a 50 on a 700).

When I first got 650's, it was on a custom track bike I was having built. Being a triathlete and roadie, I knew I didn't have lightning acceleration, and needed all the help I could get in that regard. 650's have a lower moment of inertia, meaning they'll spin up to speed easier.

Handling is more a function of the frame design than the wheel size.

Tires and tubes can be harder to come by in an emergency type situation (meaning taking a trip to the LBS), but if you stock up when you see them, it's not an issue.

Hope that helps!

The reason that they've fallen out of favor is that shops just don't want to stock another size. And you'll often hear shop employees bashing 650's with absolute BS reasons to not buy a 650-fitted bike.

Fact is that virtually EVERY production bike out there puts too much weight on the front wheel for people who ride steep (effective set tube angles of 80 degrees or steeper). Why? There used to be regulations that prevented it, but they've been loosened. In order to move the weight back, you have to do one of two things -- lengthen the front center, or shorten the chainstays. You can only shorten those chainstays so much with 700 wheels...

But so many people don't know any different, and so many tri bikes are fit on a stationary trainer...

High stem, seatpost slammed all the way down... The marks of some one who bought a bike that didn't fit.

The owner is 5'4, did IM Fla on it. He is the second owner so I may offer $500. Working out arrangements to see it this week. Are there concerns about the seat tube angle?

I'm 5'11' and have an old GT Vengeance with 650's. I also have a newer ride with 700s. I prefer 700s myself, and I like my new bike better.I found  650's to be a pain from a consumer standpoint, simply because my options were limited and had to order tubes online. 

My old coach was about 5'9 and rides a 650 with a 59t chainring. But he's a monster.

Like briderdt said, there isn't anything wrong with them. I believe the old theory was that a shorter wheel presented less frontage, being more aero. But, it seems that taller headtubes offset that, so there was no real benefit. I could be wrong.