I actually got my IRO Mark V a few days ago, set it up (will be taking it to a local bike co-op for fine-tuning over the weekend), and have spent a few miles on it. For the most part I like it a lot but there are a couple of small issues that will require switching out the stock parts (like the seat being uncomfortable after a mile or so) but one thing I wanted to ask you was ... how can I make this bike handle bumps/gravely roads better. I noticed that any fissures/bumps/cracks/potholes/gravel/sand/etc can be acutely felt and you really need a smooth road for a smooth ride.

Do you think that getting fatter tires with some treads will help? Do you know if that means I will have to get new wheels as well as new tires? Any idea what the fattest tires the IRO Mark V can fit (I realize that I probably should email IRO but I figure I'd ask here anyway)?

I've been googling the tire and wheel size system for bicycles (http://www.sheldonbrown.com/tire-sizing.html) and I'm still a bit confused on how it works.

Sidenotes: I got the FG version and bought a 17t freewheel ... but I only have front brakes. I have less than a half inch of clearance between the top tube and my crown jewels which is somewhat disconcerting ... I hope this is normal. I'll most likely switch to freewheel with a little help from the bike co-op and for convenience in commuting. I checked out this guys' IRO Mark V: http://velospace.org/node/8684 ... and he used http://www.ritcheylogic.com/dyn_prodfamily.php?k=98784 tires which come in 32C, 35C, 40C. Could I use these? Can I use any of those tire widths?