I have been reading about what seems to be a trend to convert old mountain bikes to touring bikes. It seems like a pretty interesting idea. I, having no knowledge of such things, have a question, however. I haven't seen anything written about 29" wheels on such a conversion. Would wheels this size have a place, or are they a bad idea? Just from what I can pull off the top of my head, the ones that I have seen are pretty wide. But they seem like they would eat up a lot of road. Definitely not a speed rig, but it would seem pretty stable and dependable for most anything that you would run into. Anyone want to set me straight?

Given: a "29er" is a 622bcd aka 700c rim you are just picking different Tires.

The posts to mount the cantilever brakes are positioned to accommodate the 26" rim and there would need to be enough vertical brake pad adjustment available for the larger diameter rim or replacement brakes that are able adjust.

Brad

Never thought of these things. For mounting the brakes, I guess we could get around the brake-post position by getting a frame from a more modern mountain bike. One that was originally intended for a 29", but that would defeat the fact that, from what I have read, older (80's) bikes are the types that are best for the conversion. I don't think that they offered frames that size back then. I didn't realize that a 29" and a 700C were the same size. Thanks for the insight. I suspect that these reasons are why I have never seen anyone plugging this wheel size on this type of conversion. I see why there probably would be no good reason to go to a 29" wheel on a tourer. 700C wheels come in widths that must be wide enough if one wants wide wheels/tires. Any additional advantage that a 29" wheel would give in width, would probably be too much for this type of bike. Is my thinking going in the right direction?

CLICK ME --> Measuring Bicycle Rims and Hub Flanges

Scroll down for a table showing rim sizes and wheel sizes.
Seems like a I see touring bikes going the opposite way mentioned in the original post - using 650B wheels in 700C touring bikes. This allows more rubber to cushion the ride, space for racks and fenders. The only concern would be reducing pedal clearance to ground. The folks at Rivendell say to draw the BB-drop limit at 70mm (less being better). And you have to make sure the brakes line up with the rim.

Perhaps because there are no old mountain bikes with 29 inch wheels. The use of the "29" inch wheels is pretty new on mountain bikes.

If you try it, keep in mind that many older mountain bikes might have pretty short chain stays, thus could have heel clearance issues.

Thanks for the help everyone. It has helped me get my thinking straight along these lines. I read what Sheldon has to say about the 650B. Makes sense. It seems like a 29" wheel would not give you any earth shattering benefit, and would get in the way of using fatter tires and clearance for racks and fenders. The info about bottom bracket clearance is appreciated. Older mountain bikes and frames are cheap and there is no shortage of them out there. At least not around here. I think that I am going to take this route to build myself a touring bike. I don't know much now, but I imagine that I be smarter when I am done. Thanks again.

I did my 3-month tour on a 29er. The front wheel was stock. The rear wheel was the same size as stock, but with higher spoke count. 29ers have long chain stays and good bottom bracket clearance. In fact, one of the things caused me to consider giving touring a try was that my 29er had quite a lot in common with a touring bike, geometry-wise.

700c wheels and 29er wheels are the same thing. A 29er MTB comes with 700c wheels that are wide enough to be compatible with wide tires.

No. The opposite is true. 29ers provide plenty of room for using fatter tires, racks, and fenders.

you'll find a few pic recently posted here: https://www.bikeforums.net/touring/97...tion-bike.html
of people who are using old MTBs as "expedition" bikes, or touring bikes for crummy roads (fewer cars on crummy roads, so a nicer experience).

Just to show what direction REI has taken, here is the 2015 Novara Safari, which has many of the features I think you are looking for, just to give you an idea or two. I like my 2014 model except for the color.
Novara Safari Bike - 2015

i suppose you could just switch out the fork to use 29rrr/700 wheels.
go with disc brakes and no worries about the pivot arms.
but would that (negatively) affect the geometry?

a google search will find instructions on adding disc brake tabs to
steel frames. looks simple enough.

i'm no wheel size expert, but would a 700 wheel be "taller" than a 26" wheel?
would you maybe be getting too close to the bottom bracket, or will it put the
tire in a narrower section between the chainstays?

or would it be practical to have 29er front and 26er rear?

29" front and 26" back wheel sounds cool, but I don't think that I am ready for that :-) That Nova Safari looks like it is a close result to the direction my thinking has been going. I would accuse them of stealing my idea, except of course, they obviously had it long before I did. As I continue to read about it, I start to wonder why I am not just buying one of those.

There's a lot to be said for going with a complete bike like the Safari. If you were to go with a vintage mtb, you'd want to find one from the 80s as those tended to be longer wheelbase bikes. By the 90s, they became better offroad racing bikes as the chainstays became shorter. The shorter chainstays make them somewhat less useful for touring. I have an 89 stumpjumper comp; it has great geometry for touring with a 41 inch wheelbase and lots of clearance for fat tires, rack, fenders, etc. I have a 91 team stumpjumper; great bike but the geometry is not so great for touring.

It's not clear to me whether you are talking about riding a bike made for 29" wheels, or if you are talking about putting 29" wheels on a mountain bike made for 26" wheels. It sounds like you may be talking about the second thing. If that's case, then I would not think it would be a worthwhile change to make. There is no reason not to tour on 26" wheels. Many people do, and some fairly popular touring bikes come with 26" wheels. There are also some nice 29er bikes that make decent touring bikes, but the bikes are made to run those wheels.

You can get fancy, swapping out forks, running two sizes of wheel, or just trying to squeeze a larger wheel into a frame built for a smaller one, but that kind of experimentation is usually reserved for people who like to tinker and who are trying to get a particular kind of ride out of a frame that was not design for it. It can be fun, but it seems unnecessary if your goal is to get a budget touring bike on the road. For the most part, it seems that the biggest change people want to make when using a mountain bike for road travel is to get some tires with less tread and to make sure they can mount a rack.

I've ridden 20" wheels and 700c. They both do the job. 700 rolls a little easier, but 20" packs a lot easier. 26" seems like a good compromise. If you have a mountain bike with 26" wheels that you'd like to use, I'd start with some more road-friendly tires and see how it goes before looking to make expensive wheel swaps.

Some mountain bikes will have shorter chainstays than you might want for touring. Keep that in mind when you do your shopping.

I've had experience with both 650b and 26".

IMO there's not reason to convert to 650b. A lot of brakes that have vertical clearance for 650b conversion aren't that great. Most people convert 700 to 650b for extra tire volume. However, by going from 26 to 650b, you're minimizing tire clearance.

26" wheelsets are cheaper to come by, plenty of tires choices, stronger wheel. 650b wheels that use rim brakes are hard to come by, or are pretty expensive. I would rather spend that extra money on brakes, and upgrading the cockpit.