Avid road cyclist and tourist here. tried to search but it keeps acting funky. I'm sure this is a super basic question that will get some yelling at me for asking but here goes! what exactly happens if I put 29er wheels on a 26" frame? I can imagine that there are clearance issues up front but what if I simply want to go with no suspension at all? I can buy a 29"er generic fork easily. Anyone have any sources for cheap Nashbar-esque 29er frames. Reason why I'm thinking of a 29er is that i have extra disc wheelsets for my touring bike and i can come across cheapo 26" mtbs easily and have a decent parts bin to build from. I'm sure it will alter certain angles and things like that, but I won't be looking to do too much serious off roading, I live in NYC, I want something with some larger volume tires that I can tear around through snow storms and hop off curbs with and occassionaly tear through a couple of dirt trails that are nearby

You may find you don't have enough clearance for a rear wheel+MTB tyre, my StumpJumper 26' is really, really close to the frame and I wouldn't have a chance to put a 29 wheel in there, never mind with a nice winter set of tyres (Nobby Nics). Overall, I'd advise against it. 'I want something with larger volume tyres', I'd recommend just buying some beefy tyres rather than mess with the frame geometry.
My guess, is it will push the bike higher up off the ground, and depending on bike and fit, cause problems with standover height. I also imagine it will push the front end up and make it handle like a tractor, even 29 specific frames sometimes feel this way, and it's not nice. I don't see a harm in trying, but it would be worth measuring up clearances (inc. tyres), how much more the front end will be pushed and overall ground clearance. I know it's only 3 more inches, but it could cause problems.

I know from the road bike world that there can be massive differences, I just feel like I"ve seen or heard of some people riding 69ers and 96ers but I didn't know what frame they were using. FWIW, I'm tall 6'3 so I'd be looking for a larger frame size which may or may not give me a little more leeway with some clearances but probably not. Next question. I found this 29er frame and fork for sale at a good price. https://newyork.craigslist.org/brk/bik/3400291092.html I'm thinking of asking for the whole thing for $150 as I know suntour today is a far cry from the suntour of old. I also know used cranks are easy to come by, I actually got a used deore crank for $20 last year, all it needed was new BB for another $30. I'm going to guess that the MTB world is like the Road bike world, that Diamondback bikes get LAUGHED at by serious mtb'ers yet what Iknow about frame and materials, aluminum is aluminum. Typically the cheapo bikes are cheapo because of the parts bolted on to them (i.e. suntour, low end tourney deraileurs, etc) but can anyone give me a good reason not to build up from this frame??? I'll probably strip it and repaint it eventually. keep in mind, this bike will be more of a city cruising, snowy weather, beater bike. I already have a force equipped Carbon fiber road racer and a surly disc trucker that does the bulk of my shopping, commuting type of stuff.

well, theres 3 inches of wheel= 1.5 inch of extra rim in the frame. Your problem will be the brake line. Idk if there are adaptors but unless you run it fixed gear you will not be able to use brakes Unless u have disk breaks.

although you will throw the geometry off.

You can get vbrake adaptors from xrtacycle.com for $35 each. Lets you run 700 wheels on 26 frame.

You can do that or you can just get a cross bike.

Did you end up getting that frame? The listing's gone.

Anyway I think you should be going for a 29er frame, few of the 26" bikes I see standing outside have 1.5" between the rear tire and the seat tube. If you find a frame with epic clearance, it may work, but better get one with an upright head tube so it still steers a little? Standover height probably isn't much of an issue, since when you're tall you tend to have more than 1.5" room under the sack I guess.

OK , I,m late here and the op has probably bought a frame but since the question has been asked I'll put my bike up to show actual clearances.
It shows a small size 26er frame with 29er wheels and 35c (1.25) cx tires and a 410mm cx fork. The bike gets used with 23mm tires too, a 40c Michelin Pilot slick has been used.

An older pic the steerer tube is cut down and has a Ultegra front derailleur

Cyclocross tires probably will fit on a 26" bike because the diameter is small. I am guessing that a 29x2.0 would not, but it depends heavily on your fork crown and rear brake bridge.

One of the best parts about mountain biking is innovation. The downside is cost. If you are willing to try some new things and risk the cost, you might come up with something really rideable and unique. Downside is that you might put money into a pit that never works. Everyone around here likes projects and pictures. We are all pretty much not concerned about names unless they are Huffy, Pacific or Yeti! (just kidding about the Yeti part.) Frames are pretty much all from GIANT in China, so a DB is no big concern.

Bikes are built around a specific geometry. Messing with that would be my big concern. Have you considered 27.5 tires. They seem to be gaining ground.

A 2.0 would never fit this frame near the BB. A 1.5/38c nobby would be the maximum giving a few mm clearance. When I built the bike rigid 29er forks weren't easy to get (only a niner fork) whats coming out of china now has changed things.

True money can be thrown away buying incompatible parts, I did my research though and got what I was after, the 410mm fork really quickens the steering, great for its intended use and the bigger wheels regain the lost BB height.
Jerry bicycle company (JBC) carbon frames are made by Giant and alloy frames by Hodaka which Giant mostly owns and has there alloy frames made there too. Jerry Laio (JBC founder) was a Hodaka factory BMX then MTB rider. Forgive the history lesson.
Challenge does make a Parigi Roubaix 27mm gumwall I would like to get. These Vittoria's fitted below were bought for another bike.

I did end up getting the 29er frame. Got her almost complete now, having some issues with one of the tubeless tires. so much for being able to seat tubeless tires with a pump not a compressor. no such luck here