WTB’s Frequency and KOM rims are some of the finest alloy MTB rims on the market right now – they are well made, and WTB’s TCS tubeless profile is a great UST-like design, and both do an excellent job balancing strength, weight, and width. Never one to rest on their laurels, WTB now has a new series of rims available for custom builds: the ASYM, which is available in 650B and 29er sizes. Sorry 26″ riders.
ASYM is short for ‘asymmetric’, and the ASYM rims are all asymmetric with their spoke beds offset from the center of the rim. This offset will help to better balance the spoke bracing angles and tension on each side of the wheel. It essentially raises the tension on the low-tension side of the wheel, which makes for a higher load capacity and better durability. With the spokes at a higher tension there is less chance of a spoke getting overloaded and going slack – which leads to fatigue induced spoke failure, and it can cause the nipples to back off and the wheels to go out of true. The offset raises the tension on the low tension spokes by about 50%.
There are four ASYM rims available, the i19, i23, i29, and i35. Typical of WTB’s other rims the number stands for the internal width of the rim. To be honest I don’t care much for the i19 for MTB use, it’s a lot more narrow than most people will want. It will be a good disc brake cyclocross option though. For now however, we’re going to focus on the i23, i29, and i35.
You’ve probably noticed – those are some wide rims! If you’ve been researching wheels I’m sure you’re aware that current trends and designs keep going wider and wider. Wider rims open up the tires, giving you more volume allowing for less air pressure to be used and a bigger contact patch for improved traction. The more vertical sidewalls, and less light bulb shaped cross section of the tire both make for a more stable and well supported tire, which improves feel and confidence in the corners.
The ASYM i29 and i35 rims are some of the widest alloy rims available right now. These will be great for riders wanting to try really wide rims who do not want to spend the money for carbon rims. Wide carbon rims are much lighter of course, but they are also much more expensive. The i35 will even make a good Plus size rim. It’s quite a bit lighter (605g vs 711g) than the WTB Scrapper, the original Plus size rim, but not quite as wide (35mm vs 45mm). Being a bit narrower will be good for many people doing Plus conversions where clearance might be a bit tight.
Weight wise the ASYM rims fall inbetween the KOM and Frequency, and are much closer to the KOM, so they are reasonably light for their widths. I have weighed a pair of each width in the 29er size, the 650B weights below are educated estimates. Probably not spot on, but should close enough. I’ll update this post as I build and weigh the 650B sizes.
|Size||ASYM i23||ASYM i29||ASYM i35|
The ASYM rims do not use WTB’s ‘4D Drilling’ like the KOM and Frequency rims, but instead use eyelets. The graphics are subtle, which I like, and they are decals that can be easily stripped off for an all-black stealthy look. I would like to see a platform of some sort at the valve hole, like Nox does on their carbon asymmetric rims, or have the valve offset like the spokes. Because the rim is not symmetric, but the valve is drilled in the center of the rim, the valve not does not have a completely flat surface to tighten onto, and will pull the valve into a slight angle. It’s locked solidly in place and isn’t a functional problem, just looks a little wonky.
EDIT April 2017 – WTB has made some running changes to the ASYM rims and the valve hole is now drilled offset like the spoke holes, so no more crooked valve!
Pricing is in line with other alloy rims, a touch less expensive than the KOM and a few dollars more than the Frequency rims. The ASYM rims of course use WTB’s excellent TCS tubeless profile. If you’re interested in having a set built just for you, fill out my form or send me an e-mail and let’s get the process started!