[photosbymark]

This is one of those days where I have time to ponder the odd question for a minute.

A 700c wheel is the same size as a 29er. I wonder how a road bike would ride with big old fat 29 er tires on it? This is probably the compromise that gives you the worst possible compromise someone could possibly imagine, but maybe not as bad as one would think.

For a relatively level dirt trail that really is semi improved and not technical, it just might be faster. The weight of the rider would be more forward I would think than a regular mountain bike, and the grandma gear for the extremely steep climbs wouldn't be there. A road bike certainly wouldn't take as much abuse, but those big fat tires would keep you from digging in. With the drop handle bars you would be more aerodynamic (and personally I think more comfortable regardless) and the gearing should be more speed than climb biased. Probably doesn't make as much difference to a spinner as it would to a masher. The whole thing may be moot if the tire physically will not fit between the stays.

I saw a site for a trail, I think it was across Missouri that was a couple of hundred miles long, but dirt that goes across nearly the entire state. For a tour like that, it just might work. Just wondered if anyone has ever tried it and if not who knows. Maybe I will pick up a set of tires for grins and see what it does.

[LarryM]

I have a 2005 Giant Cypress DX with 700x40 tires. While the tires are a little too narrow to formally make the bike 29er, the 40 width handles very well on crushed stone, most gravel roads, and on packed dirt.

The Missouri rail trail of which you speak is probably the the 237mi Katy Trail running from Machens, near St. Louis, to Clinton. About half of of the Katy is on the Adventure Cycling Lewis & Clark route. The surface is hard packed crushed stone. My wife routinely rides crushed stone trails like the Katy with 700x32 tires on her Jamis Aurora. Her tires will handle most gravel roads, too, as long as the gravel isn't too thick.

We have made plans to ride the Katy 4 times, but cancelled every time. Something came up a week or so before departure that made us reconsider and go somewhere else. The issue was generally weather related, like extreme flooding along the Missouri River. Still want to ride it some day.

[photosbymark]

Well I think I have a 23 on the road bike now. A 40 should do far better, so maybe the idea isn't as crazy as I thought. I think the Katy trail is the one I was referring to. Some time ago there was a piece that Carl Edwards rode the trail with a couple of his buddies and it looked like it would have been a blast to ride. It's on my one day list

[qmsdc15]

The problem is a road bike doesn't have room in the fork and stays for a fat tire to fit.

[Noel]

Sounds like a job for a cyclocross bike.

[photosbymark]

I really wondered if there was room for the tires. Noel you are right its a job for something other than a road bike. A cyclocross or a mountain bike with maybe a few mods would definitely be a better choice. Yet I don't own a cyclocross bike and I could modify my mountain bike a bit to make it a better fit. Granted this would be a bit like using a crescent wrench on a bolt that a ratchet would work on.

[LarryM]

Mark,

Are you aimimg to put on tires wider then 40mm or are you looking for a tire suitable for crushed stone trails like the Katy?

[photosbymark]

After looking at my road bike, the physically isn't enough room for a real wide tire between the stays. Some of my old ten speeds you could have put a rear tire off a top fuel dragster and it would have fit. Really I have a trip coming up that a road bike really is going to be a better choice, as is 99% and maybe all of it will be on pavement. Might even take the Sunray, but probably the road bike as its much much lighter. Yet there are one or two trails that are possible, and if changing a set of tires makes it more practical, its something I could do far easier than 2 bikes or a bike that would less than ideal for such a high percentage of the trip.

[LarryM]

If you're looking for something wide enough for crushed stone trails, like the Katy, a set of 32s would certainly do. That's the OEM size on touring bikes like the Trek 520 and Jamis Aurora, neither of which is particularly wide at the stays. LHTs are delivered with 37s these days. It might be worth seeing if something in the 32-37 range would fit.

Sounds like a fun trip. Where are you planning to go?