Yes. No. Maybe?
 

If I was looking to build a single speed MTB, would this be a good place to start? I could just as easily convert a $100 steel MTB, but this has horizontal dropouts, with adjusters. The downside is that a fork won't be cheap, and it may end up getting spendy to build up a super inexpensive frame.

Opinions welcome, since it will probably sell quick if I don't get back to the guy soon.

I have no advice with which to help you, but that's a nice looking frame. If it's only $20, there isn't any harm in buying it now just to be able to snatch up the deal. If after buying it you find out that it'll be too costly to build it up you won't have lost much. Hm, maybe I did have some helpful advice.

Those dropouts don't look quite long enough to adjust your chain tension much, so you'd either need to hunt a "magic" gear or a chain tensioner, which looks ugly to most.

It WILL be expensive to build up an inexpensive frame, and time consuming, so while it might be a valuable learning experience, you might be happier with one of these http://www.bikesdirect.com/products/...tcast29_08.htm for $349.

it's a sweet frame. And since it's already stripped you could do many things with it.
A half like will take care of the shorter drop-outs no problem.
The new fork will be about $150. If you look around I'm sure you can get a used one for under $100 though.
I would go for it. It would probably be fun and a nice learning experience.

Did you look at the picture? There is plenty of room for adjustment.

I'd be mostly concerned with frame fit.... might be able to get a 2' long seat tube tho ;)

Most fixie stuff work for a MTB..... just use some spares or extras (I'm pretty sure in the end all you'll need is the wheelset w/ tires&tubes and the fork)
It also helps to buy used from your bike store... the LBS's around my place has tons of used MTB stuff when compared to road


The cost of a decent new mtn bike fork (uno like something from SRAM or fox) is going to cost around 5X+ your frame lol
Pretty nice looking frame anyway; there's plenty of room there for customization, even down to the paint job!:D

Doesn't a dirt-jumping frame have a considerably different frame geometry than say, an XC mountain bike? (honest question, i have no idea?)

I would say for $20 you cant get hurt too bad as long as the frame is the right size. If you build this frame up and decide it doesn't work well for you there is always the option to get a different frame and just transfer the components (assuming the new frame uses the same seatpost/headset/etc.

I told the guy that I'll pick it up today, if no one else gets to it first. For $20, it will probably sit around while I wait for a few good deals to fall into my lap.

Yes, the geometry can be quite a bit different. Brian, what kind of riding were you hoping to do with this bike? If it's urban or dirt-jumping, go for it, but if you're looking to just ride trails, I'd look for something else. A 130mm travel fork is pretty burly for just XC.

I have a trail bike, and I have a BMX bike. I was thinking something to just knock around on, or let my kid ride. The 130mm it had was way too big, as the stock fork is only 100mm.

It would be good for urban and dirt jumps, sure. Though you might find it less expensive to just start with an inexpensive complete dirt jumper like a specialized P1 or one of those GTs. You're not looking to trail ride or ride long distances, right?

I'm pretty sure that with my connections, I could build it up for another $200, not including the parts I already have lying around. Of course, I forgot to call the guy today.