+1 Even if these second hand hubs cost you the same as "bargain" brand hubs that are new, they will likely outlast them.

While there ARE some inexpensive products out there that work the trick is to know what is cheap but good vs cheap and bad. For that sort of decision I pretty much rely on reading reviews of the stuff and then reading between the lines of what is said by the reviewers. It's still a gamble but at least you can go into the purchase with a bit more of a feeling.

For some reason the link didn't want to open for me until just now. From the looks of the picture I'd say this is a basic cup and cone hub and any seals are likely just rubber lipped guards on the shields that push in on either side. About all that can be said for it for certain is that it's a quick release style.

For a basic screw on freewheel hub and from looking at the others on the Niagra site I'd say that this is likely decent enough hub just based on the pricing of this one vs the others. And for the amount of riding you say that your friend will be doing it's likely that it'll do just fine. It's very likely going to be a better hub than the even cheaper ones shown. If it were me looking for a hub of this type for a vintage bike rebuild of some sort I'd likely go for them as well. Certainly compared to some of the other freewheel hubs shown on the Niagra web site this one has a much cleaner exterior look in the pictures vs the obvious machining marks on some others. And since USUALLY the inside quality matches the outside I'd say that gambling on two of these hubs would not be too risky.

Keep in mind that you still need to buy QR skewers for them.

Thanks for all the info everyone. I think I'm gonna slip into the bike co-op periodically over the next few days to check the used bins, and if I find some that seem good I'll pick em up. If if can't find a pair that match (or at least look similar) in good shape I might just try some of the ones on the Niagara site. I just noticed however, that the ones I linked to in the first post are listed in the "MTB Hubs" category. Is this actually significant? Are they going to be different in some way that is going to cause a problem for use on a road bike?

MTB rear hubs are spaced at 135mm and modern road bike rears are 130mm. The fronts on both are 100mm. On a steel framed bike, you can spread the dropouts to fit them in but if you are scratch building the wheels, why not get hubs that fit? Note that older road bikes used 126mm or even 120 depending on how old.

An important question that nobody here seems to have asked is this: How heavy is your friend, and what kind of terrain will she be riding on? You've already mentioned that this is for a single-speed freewheel build, she's not a commuter, and you don't expect her to put thousands of miles on this or any other bike, so I'm guessing we're talking about pavement only, no curb-hopping, and nothing crazy. If she's pretty light, I'll beg to differ with just about everybody else on this thread and say that you're completely safe going bottom-of-the-barrel on the cheapest regular cup-and-cone hubs you can find.

The reason I say this is because I'm a 160 lb daily commuter in wet, nasty Boston, and I've put 20,000 (yes, twenty thousand) miles on a low-end Shimano Acera freehub that I've had on my Kona for 11 years (almost worn through the rims on the front wheel of that one), which sees mostly commuting with some curb-hopping and some light mountain biking, and around 10,000 more over 5 years on a bottom-of-the-line Quando freehub and 4 years on a Quando track hub which see only road riding. All of these are basic, not-really-sealed cup-and-cone loose-bearing hubs, but I keep them well-adjusted. My tandem has higher-end hubs.

To be fair, I've never broken a spoke either, but I keep those tensioned pretty well and I suppose I've been lucky. But I really suspect that for your friend, unless she's heavy, even mid-range components would be overkill.

New style XT hubs are a throwback as far as quality. Oversized aluminum axles, 3/16 ball bearings in a retainer (wtf shimano?). Have seen several severely locked up hubs where the bolt that holds the freehub body onto the hub shell unscrewed itself. These hubs are no longer used in loaded touring situations for example. Many builders in that field go back to LX hubs (FH-T660), which is basically a revamped Tiagra hub with better seals. It does have the reliable steel axle and 1/4 inch bearings.

HAHAHA!!! LOL, you mean I got a good deal when I bought a 36 hole Shimano Tiagra rear hub on sale for light touring?

By the way, I got a WTB Freedom Ryder 23 thirty-six hole double wall rim as well and 14G/2.0mm DT Swiss straight gauge spokes. I can't wait to have it built. (I also bought a Shimano DH-2N70 dynamo hub on sale on eBay for $33 CAD. Even if it's only 32 hole and 2.4 watts, if I buy a Busch & Muller Lumotec Lyt, it might a pretty good deal price-wise.)