djb

my understanding of the 29 vs 26 vs 27.5 is that in mtb, the larger 29 rolls over obstacles easier, 26 steered faster and has less toe overlap, 27.5 is the compromise that works better for better steering response and working better for frame geometry issues.

on road, you hear and read that a larger/heavier wheel will maintain speed easier, but a lighter wheel accelerates faster.....

how does this apply to touring?? I don't know, but my feeling is that on a bike+load that weighs 50, 60, 70, 80lbs, I suspect the differences are small--assuming you are on roads.
I can see that larger tire size on rough terrain could roll over stuff easier, which kinda makes sense to me, and would be nice if riding on rough stuff all day.

djb

I have read that someone clearly found that the 700 LHT steers slowly and like a truck, whereas the 26 version changes how it steers, ie quicker and more fun.....the opposite of what you mention--this relates to what I wrote about why I like the Troll, although totally diff frame design, so a diff animal.

robow

djb, I built up the 26" LHT below several years ago and though I have ridden an LHT in 700c, I never had them at the same time to really do a fair comparison. I think the fellows at Surly claimed they felt the 700c LHT "rolled better" not that it was more agile. I don't think we're in disagreement anywhere. The bike below was very "comfy" to ride but it was a slow pig. It was stable like a bus but not really agile by any means and that was due I'm sure to the long wheel base and weight and not due to the 26" wheel. It made for a very fine tourer and commuter but I wouldn't call it exciting to ride, it was just too damn predictable (just as it was designed to be)

himespau 

If you make the stays and fork crown wide enough and run disk, can't you just swap in whatever size you want? I've never done disk brakes and not sure I'd want to because calipers and cantilevers work so well for everything I need, but, if you're building anyway and want to try something new, it seems like that could be a way to go.

Tourist in MSN

Within reason, yes. Some people will have a set of skinny tire 700c wheels and also a set of wider 650b wheels for the same bike. But the total diameter of tire on the pavement is quite similar in that example, thus handling is not impaired. But if one set of wheels puts the axles significantly closer to or farther from the pavement that the bike was designed for, that could impair handling.

djb

and or putting the bb lower, and perhaps creeping into more annoying pedal strike area.
Ive never gone down with pedal strike, but it always makes you wake up and smell the coffee pretty damn quickly!

ironwood

How tall are you? I think small bikes look better with 26" wheels and tall frames look better with 700c. In between 650B is just right. Other things to consider are toe clip overlap and bottom bracket height.

TiHabanero

Committed to staying with the 700c wheel size after taking a couple of other bikes down a few really rough gravel roads. The 26 inch wheel with an 1-1/2 tire road noticeably sharper than the 700c with a 37mm tire. Should have done the side by side comparison in the first place instead of relying upon memory from a month ago. Getting the tanks charged and will be making fire soon.

djb

Hi ti, don't recall of I mentioned before, but of course frame geo plays a huge part here. I've ridden in the past a 700 bike that steered too quickly, and I own an old GT hybrid that despite 700x35 tires, fenders with no toe overlap, is the quickest, most nervous steering bike I own, almost to the point of being too nervous. It is way more nervous than my troll or my old mountain bike, both 26ers, so clearly there is a frame geo thing going on that is inherent in the design.

From your last comment, you disliked the quick steering of the 26 bike you rode, but all my point is, is that an overly quick, nervous steering bike is all in the frame geo, not necessarily just because it's 26 vs 700.

It's interesting or curious to me that my old GT hybrid, as well as a friends Giant hybrid I rode once, marketed at regular weekend, occasional riders, both have such nervous, almost to the point of dangerous front end behavior. I certainly feel my GT is right on the edge of dangerous, and have to be wary of it, especially at any reasonable speed-- and I have a lot of two wheeled experience going fast and like a fast front end, but the GT is right there at the edge of being too quick and unstable. The friends Giant was the same, and my theory is that the frame designs were for dropbars, and therefore the main weight of steering axis would be much further forward--combined with head tube angle and trail stuff I guess, neither of which I have a proper understanding....
Just my theory anyway. But it's clear to me, that despite being someone comfortable riding at rather high speeds on two wheels, motorized or not, that my 700 wheeled GT is pretty damn twitchy and overly sensitive at any speed over 20kph, where my troll is confidence inspiring at any speed I've gotten it to, about 80k or 50mph.