Brocephus

I'm considering a bike on my local used market, that's a 9-spd urban/metro type bike, that will have some very low-end 700c disc wheels on it, with 700x42 tires on it (and rigid fork), and I'm looking at better (but still budget oriented) wheel upgrades, and the best options I've found are on a couple sets of 29" mtn wheels (w/ 6-bolt XT or Deore hubs). So, as i understand, the wheel diameter shouldn't be an issue, but I'm wondering about any other compatibility/fitment issues, like the original cassette mounting on the XT or Deore hub, and the new wheels/hubs fitting in the frame and fork. Is there any significant hub width difference there? Any other concerns I'm oblivious to?
Any help is much appreciated....

EDIT: I just did some more searching, and this bike has Acera shifters and rear derailleur, which are actually a mtn. group, so there should be no compatibility issues with whatever cassette is on the bike, going on a mtn hub. I contacted the bike manufacturer about the original wheels, and was told the thinnest tires I could mount on the factory rims would be about a 38, so I'm thinking these are fairly wide rims, for 700's.

fietsbob

622 = 622 , its the width and application that differs '29er' is a wide 700C, '29er +' is an even wider tire..

your Frame clearance, width/height, is the limiting factor ..

Iride01 

Spacing between the dropouts is a consideration between some wheel builds. Ignore whether it say mountain or road and look for the spec's that tell you the actual measurements.

Wheels intended for mtn bikes might have a spacing of 148 mm between the drops while many road bike wheels will be expecting 130. For bikes of mixed heritage, you need to see what the mfr did.

Brocephus

Thanks fietsbob, I just looked at a video review, and there appears to be plenty of clearance on the fork, but couldn't tell anything about the stays, but I'm thinking if it's built around a 42 tire width (and with all the extra clearance I saw on the fork), something like a 1.75" mtn tire would probably clear ok. (this is all still academic at this point, I'm not ordering anything till I've picked up the bike, and can see how much clearance there is.)
One more thing, I assume there's no hub-width issue to be concerned about?

Leebo

Mt bike hub widths can vary( wait for it) 135, 142, 148 and now 157. Guessing you used bike would be either 130/135.

Brocephus

Ah,ok, thanks, this is exactly what i was most concerned about. Are 130 and 148mm pretty much the only standards I have to worry about ? ( I just saw that Leebo answered that already. This is getting complicated.)

Iride01 

That is why you need to learn the actual specs. Don't trust the description of Mountain, Road, Hybrid or whatever. Online retailers are starting to go back to giving little info on useful specs. So I wind up looking on the mfr's website to find them. Some mfr's are better at sharing that info than others.

Also.....

Rim brakes or disc? If disc, then you'll have the added complication of how they attach to the hub.

Metaluna

No the width is only half the information you need for matching the hub axle. There are two "worlds" when it comes to modern hubs -- those with quick release axles and those with through axles. Quick release (QR) is the older and more common style, and probably what you will find on a lower end bike. If the bike you're looking at has disc brakes and is mainly using mountain bike components (e.g. Acera), the rear wheel most likely uses a 135mm QR hub. 130mm is more common on QR hubs intended for rim brake road bikes. Both disc and rim brake QR bikes use 100mm spacing in front.

So the good news is, if your bike uses QR axles, your homework is pretty much done as far as hub standards are concerned. Any QR disc wheelset is likely to have a 135mm over-locknut distance in the back and 100mm OLD in front, and possess a standard Shimano freehub that will work with at least 7-10 speed cassettes (and possibly 11 speed). The rotor mount standard will either be 6-bolt or Centerlock. My impression is that it's a bit easier to find cheap rotors in 6-bolt but maybe that's changing.

If the bike has through axles, it gets more complicated, but most likely it needs a 12x142mm hub on the rear, and 12x100 or 15x100mm on the front. The wider rear hubs (e.g. 148mm Boost, 150, 157) I think are still mostly found on higher end mountain and downhill bikes. I could be vastly out of touch, but I think you're unlikely to encounter any of these standards in a budget wheelset so you probably don't have to worry about them much.

Also, many modern hubs have replaceable endcaps that allow you to convert the wheel between QR and various through axle standards, usually 12x142 at a minimum for the rear and 12x100 or 15x100 in front. These are the only types of hubs I will consider lately since I have a mix of QR and TA bikes now (even my fork mount roof rack has replaceable endcaps!). I don't think Shimano has this feature on most of their hubs so you'll need to know the axle type on the wheels you were looking at.

Here's a pretty good summary of many different hub types (except it doesn't cover Boost...maybe that wasn't available at the time this was written)
https://forums.mtbr.com/wheels-tires...ed-873910.html

Brocephus

Thanks metaluna, the bike has standard QR's, not TA, and the rotors are the common 6-bolt, so it sounds like I won't be looking at any compatibility issues (the wheel upgrades I'm eyeballing have Shimano XT 6-bolt hubs.)
Thanks to all for weighing in, it's been helpful !!
(I love it when an internet forum works like it's supposed to, LOL!! )

dsbrantjr

I am seeing a lot of "guessing", "maybe", "probably" and "most likely". Why don't you just ask the seller to measure it, or go and measure it yourself?

And what perceived advantage will these upgraded wheels provide? A cheap, true wheel will roll as well as an expensive one.

Ironfish653

If you like the bike that much, then get it; Then you can spec your new wheels from the bike, as it sits in front of you, not just by guessing from the pictures of it.

Since the bike is a 9-speed, Wheels, cassettes, and all should be pretty much plug-n-play. It's once you hit the 10-sp generations when Road and MTB diverged, that things started getting weird.

Brocephus

I currently weigh about 210#, and have had issues with cheaper OEM wheels ( Cannondale's Codas, Fuji's Ovals, etc.) staying true, breaking spokes, and lower end hubs with lower quality seals needing more frequent service. If I can bypass the cheap generic wheels (the corner-cutting weak link on most lower end bikes), and get a set of solid name-brand rims, with XT or 105 hubs, laced up with Swiss DT's, for under $200 delivered, where's the downside?