It is 126mm, however the hubs that I have for it are 135mm, and I am not going to put enough money into the bike to buy a new wheelset - this is a commuter build on an old road frame, using tires from a 700c hybrid bike. I was able to score a nice road frame, with most of the other parts, except wheels and brakes, from a local guy for $35. I'm glad I got it before the fixed-gear crew found out about it.
The front fork is 96mm, but I can get that up to 100mm with a threaded rod and some nuts.
Both the fork and dropouts are very rigid and I can almost, but not quite, get my wheels into them. They stretch about 3/4 of what is needed. I am mostly worried that the rear dropouts will have weak spots and bend in the wrong place.