I'm looking at an IRO Mark V Pro frameset. I do think the the upgrade to 631 is worth the $30, but there is a possibility that I'll run SS on occasion (actually light off-road trails). So, my questions are:

1) Does the Pro have the rear bridge in the same position as the regular Mark V?
2) Does the Pro have the same rear tire clearance as the regular Mark V?

I'm not too worried about the front as I've got a fork I can use that will give me a small cross tire up front. I've also emailed and have been calling IRO since mid last week and have come up empty.

I have a Mark V Pro, so let me try to answer your questions.

1) The Pro does not have a brake hole in the rear, so no rear brake.
2) I am running a 32c on a Velocity VXC in the rear, and still have plenty of tire clearance. I biggest tire I could fit on the front was a 28c Rando, the 32c will fit after a little filing, but it didnt clear the brake I was using.

So no luck on running SS. I did swap out the fork on my bike with a Bontrager Satellite carbon cross fork, but the bike handled like crap. You need to use a fork with the same amount of rake as the stock one, or the handling will go to crap.

Thanks for the reply. I know it's not drilled for a rear brake, but that's easy to fix I'm concerned if the bridge is in the right location for a brake.

Thanks for the heads up on the handling. I did check out that fork and quickly measured mine. My fork is 2cm axle to crown shorter and has .5cm less rake so hopefully I'll be okay.

I guess I could also try some fixed off-road. I just have to keep up with my 8yr old, so it should be doable.

dumb question: do IRO framesets come with a cut fork or not?