WTB Asym i35 Rims, 27.5”

The Build

I laced the Asyms up to some White Industries XMR hubs via some DT Swiss Competition 2.0 / 1.8 butted spokes.

They came together pretty easily and quickly, no complaints there. The spoke tension ended up with an average of about 120 kgf on the rear drive side, and 105 kgf on the non-drive side. In the front, tension on the non-drive side averaged about 120 kgf, with drive side being slightly lower.

The Ride

There are a few reasons why a lot of people like wide rims, myself included.

First, they give more support to the sidewalls of the tire. The tire takes on a much more squared-off shape, which means when you’re cornering hard, the sidewall feels much less squirmy. This, in turn, leads to two other benefits:

First, a sidewall that squirms less also burps less. So wider rims generally work better when running tubeless.

Second, (and a related benefit) is that you can get away with running lower pressures. This is partly because you don’t have to worry about burping as much, and partly because the tire just feels less squirmy, so folding the tire over in a corner is less of a problem.

Really, what this all boils down to is more traction. The squarer tire profile gives more traction while climbing, more traction while braking, but most noticeably, they really lock into corners.

I’ve been running the Maxxis 2.5” DHF / 2.4” DHR II Wide Trail tires on these rims, and all I can really say is, Holy shit they corner hard. And yes, the tires get plenty of credit for that, but I’ve run those exact same tires on other, narrower rims (28mm internal), and while they were good, they’re better on the Asym.

I’ve been running 25psi front and rear, and there’s substantially less tire squirm on these rims than using the same tires at the same pressure on a narrower rim. And I was able to go down to around 20psi before the squirminess started to get annoying. (For reference, on a narrower rim, I’d run these tires at around 27psi front and 30 psi rear.)

The other noticeable upside on these is that they’re pretty dang stiff. Slapping these things into corners as hard as I can doesn’t reveal much in the way of flex, and a lot of the credit for that goes to the rim.

Now, these rims aren’t without their downsides. The biggest and most obvious one is that, as I mentioned above, they’re not particularly light. While the carbon options at this width are obviously way more expensive, they’re also a lot lighter. And since this is rotating weight, it’s fairly noticeable.

The big squared-off tires also roll noticeably slowly. Of course, some tires roll faster than others, but comparing Maxxis tires on these rims to the same Maxxis tires on narrower rims, the more squared-off profile makes for a slower rolling setup. My seat-of-the-pants impression is that they’re maybe 5-10% slower than the same tire on a narrow rim.

There’s also the issue of tire selection. Some tires work better on very wide rims, and generally speaking, the narrower the tire, the less likely it is to work well. I was running Maxxis Wide Trail tires which are designed specifically for wide rims, and there are some other companies that are starting to produce tires designed around wide rims as well.

But a very squared-off tire will corner a bit differently, and it’s not always preferable. On one hand, it makes it a bit easier to really pressure the side knobs in a corner. But if the tread pattern doesn’t work well with the squared-off tire shape, it’s possible to “run out of knobs” — basically you’re leaning past the side knobs in harder corners.

I don’t have any magic formula to figure out if your favorite tire is going to work well on a wide rim like the Asym. I can tell you the Maxxis Wide Trail tires work really well, and for the 27.5+ crowd, these rims should provide good support for tires that are at the smaller end of the 27.5+ spectrum. Beyond that, it comes down to some guess and check (or perusing online forums for opinions). I’ll update as I try different tires on these.

The final pseudo downside is that with 2.5” tires mounted up on these rims, they just look massive. They aren’t actually that big—as I talked about in the Maxxis write up, the actual tread width is about the same as on a narrower rim, but looks can be deceiving.

Here’s my normal trailhead parking lot discussion:

Random Guy: Ooooh, are those plus-sized tires?
Me: No, they’re just 2.5’s on wide rims.
Random Guy: They look like plus-sized tires. How do you like them?
Me: They’re not plus-sized tires, but I like them a lot.
Random Guy: Sweet! I really want to try those plus-sized tires!
Me: (grumbling while trying to be polite).

Another trailhead conversation is with “fat bike guy,” telling me how I shouldn’t bother with plus sized tires and I should just get a fat bike.

Durability

These rims have seen about a month of use, and so far, I have nothing to report: no dents, and I haven’t trued them at all. That said, I also haven’t done anything on them where I’d really expect serious damage.

One month isn’t really enough time to draw any strong durability conclusions, so only time will tell. As a semi-related reference point, I’ve had the Frequency i25 rims for about two years, and they still see off-and-on use. They’re made out of the same material, and they’ve held up very well.

Bottom Line

There are a lot of attractive benefits to wide rims, and the WTB Asym i35’s offer up all of them in a pretty affordable package. The Asym is a nicely designed rim with well thought out features.

If you’re looking for a super wide rim but weight remains a primary concern, carbon is still your only real option. But to the best of my knowledge, there isn’t anything else on the market that can compete with the WTB Asym in terms of price and width.