So what the heck makes the CR18 such a fine bit of extruded aluminum?
- See those three chambers? Nice design. Sort of a honeycomb between the inner and outer rim walls for strength. Mavic's double-eyeletted rims accomplish the same thing (and are probably lighter) but cost a bunch more.
- That's supposed to be a single stainless steel eyelet on the inner wall. The online fora can (and will) debate endlessly about the causes of rim cracks, but in my fleet, it's been the no-eyelet rims that have cracked around the spoke holes, not the eyeletted ones. So on my rides, eyelets are good.
- Building on a budget? CR18 is your friend. The Amazon spam (Spamazon?) price above looks to be about $30, though some careful hunting can find them for as little as $23 a rim. You can barely buy a Mavic sticker for that much.
- These things are tried and tested. I bought my first set of CR18s in 1994, and I don't think it was a new model in the lineup even then. I suspect that the longevity contributes to the price, since the tooling must have been paid off while I was still a pimply-faced adolescent.
- The width is right around 23mm, so they can take tires from 28mm up to massive. Narrower than 28mm, you probably want a racier rim, but if you're equipping a real-world bike for surfaces that aren't glass-smooth, you're golden. My old mountain bike (the one that got CR18s back in the 90s) rolled on 26x2.2 (Panaracer Smoke/Dart, baby! old school fatties!) with no ill effects.
- It doesn't matter what freaky wheel size or hole drilling your bike needs... there's a CR18 for it. From dinky little recumbent wheels up to 27" (a.k.a. 630mm BSD) and just about every stop in between is covered. Need just a few holes? Or maybe a whole lot of holes for a tandem? Got 'em. Even that freaky 650B aberration (a.k.a. 584mm BSD) is in there, though there are rumors that Sun may have missed spec on the large side with those.
- If you're a magpie, there's a CR18 with a polished finish in addition to matte silver and black. Looks pretty decent on a classic/retro bike once you peel off the (not terribly obtrusive to begin with) stickers.
- Some models have what the marketing monkeys call ABT: Advanced Brake Track. In human-speak, they just sand off the anodizing that would normally get sanded off by your brake pads, so you get better braking right away instead of after a break-in/brake-in period.
Now lest this sound like a pure Sun love-fest, the CR18 isn't quite the perfect rim. As mentioned above, if you're running skinny tires or building a superlight hill-climb bike, you'll probably want something racier. Better wheelbuilders than yours truly (which would include just about all wheelbuilders) report that some CR18s can be slightly wonky out of the box, making them more challenging to tension and true. Also, I've ridden some with fairly pronounced seams that pulse under braking. But for their price, you'd be hard-pressed to find a better all-purpose rim.