Update: I now have around 25 days on these rims and overall I have come to think of them as a wider Stan’s Arch EX rim with a better bead hook. I noted in my initial review that I hadn’t ever burped a tire with the WTB bead hook, whereas I have periodically burped tires on Stan’s Flow and Flow EX rims. On the WTB KOM i25’s, I’ve now run a 2.4” Maxxis High Roller II (until worn out), and a 2.3” Maxxis Minion DHF and haven’t experienced a single burp.
Comparisons
The Stan’s Arch EX weighs 420g and is 21mm wide (internal width). The WTB KOM i25 is heavier at 466g, but supports the tire better, both because of the improved bead hook and the greater width (25mm).
If you really want to go lighter, you can go with the narrower WTB KOM i21 that matches the Arch for width and comes in lighter at 395g (stated weight). However, I’d personally run the KOM i25 over an Arch EX in every situation because of the better bead hook and the option to go with a wider rim that isn’t much heavier.
If, however, you are looking for the durability and stiffness of a WTB Frequency Team i25, Stan’s Flow EX, or ENVE Carbon rim, the KOM i25 does fall a little short on both counts. It is more on par with a Stan’s Arch EX rim for stiffness and durability.
By my seat-of-the-pants impression, that means that it’s roughly 20% less stiff and less durable than something like the Frequency Team i25 or a Flow EX, but it does offer the same width as the Flow EX at a weight comparable to an carbon ENVE M70 rim. I found that meant they gave a more compliant and forgiving ride that I especially appreciated on the stiff Santa Cruz Nomad frame I bolted them to.
Durability
After around 20 days of riding, I did finally dent one rim. But it was in a stupid moment when I jumped a rocky section of trail and landed on a pointy rock. I expect that the dent is a bit bigger than it would have been on a WTB Frequency or similar rim, but I believe that they still would have dented. Even so, the dent on my KOM i25 it isn’t big enough to cause any tension or tubeless setup issues that would make me want to replace the rim.
I dented one sidewall in that incident, but the rim is otherwise still true and round. Blister reviewer Marshal Olson has been on this same rim in the 29” version, and has apparently had a worse experience with the durability. But he is much heavier than I am. Look for his review in the future, and know that if you are over 180 lbs or so, that his findings might be more applicable to you than mine.
Best Uses
The WTB KOM i25 offers a great value for a light, all-mountain rim. If you aren’t a particularly big rider, they should hold up just fine. However, if I were building up an enduro race bike or just an all-mountain bike that I intended to ride DH on as well, I’d think hard about how much wheel stiffness I wanted, and I’d probably use the WTB Frequency i25 rim instead of the KOM if I wanted a stiffer wheel.
In the future, I will likely run the WTB KOM i25 on my front wheel and the WTB Frequency i25 on the back to get a nice blend of stiffness where I need it + weight savings where possible.
Bottom Line
The WTB KOM i25 is reasonably priced and very light for its width, but it does give up a bit of durability and stiffness to other rims in its class. They aren’t magic, and they are in line with the adage, “light, strong, cheap—pick two.”
But the WTB KOM i25 is more durable than I initially expected, and while they are slightly less stiff than a WTB Frequency or Stan’s Flow EX rim, they still represent a good value at a competitive weight.
I built up a set of KOM23’s on DT hubs (DT Comp race spokes) for my Giant Trance and grenaded the rear in fairly short order (on Mill Creek Trail in FoCo). I rebuilt the rear with the i23 and it’s been solid. On the front, the KOM has been fine, even after doing a little lift-served riding.
For riders in places with less abusive (rocky) terrain KOM’s are really nice rims. For more aggressive riding, I’d say a front KOM should be OK, but the minimal weight and cost penalty of going to an i series rim out back is well worth it.
“In the future, I will likely run the WTB KOM i25 on my front wheel and the WTB Frequency i25 on the back to get a nice blend of stiffness where I need it”
Don’t you mean durability? In the rear, you generally want more durability, since its usually the rear wheel that takes a beating. However, I can’t imagine why you’d want more stiffness out of the rear (as opposed to the front)? I would think almost the opposite (stiffer wheel up front for tracking and cornering).
Lindahl,
The durability would be appreciated as well, but I do mean stiffness.
I agree that I want more stiffness out of the front wheel, but it isn’t as simple as saying that rim stiffness = wheel stiffness. Because of the typically narrower flange spacing on a rear wheel, it is quite a bit less stiff laterally than a front wheel using the same rim and spokes.
-Tom
Hi. How much did the entire wheelset Weigh? How would you compare your build to the dt swiss 1501 spline set that for enduro in 27.5 weighs like 1500 grams?
I don’t have any time on the DT wheelset. My wheel build was pretty heavy because I was using Hadley hubs. They are much heavier than DT hubs, but that weight is concentrated at the middle of the wheel so I’m not worried about it.
The DT is a system wheel with proprietary parts. My wheel is a handbuilt wheel with standard spokes and nipples. That difference matters to me, but not to many riders.
Interesting observation. I destroyed my front i25(non-bike accident) and rebuilt it with a KOM recently. I look forward to trying it out in spring. Hopefully it will provide a good balance up front with an i25 out back. I have been pretty impressed so far with the i25 Frequency and the KOM should be similar.
I do have to say after riding different front wheels on back to back rides over a couple months that the KOMs are definitely more flexy than the standard i25. If I had to do it over I would have waited or gone for a different wheel. I’ll now be using the KOM wheel on my hardtail and moving the i25 over to my 160mm bike. I do like both rims as tires seal up easily but I don’t want THAT much flex on the front. I like the standard i25 because it strikes the balance between light/soft and carbon.
My three rims WTB KOM
Thanks for the great review. It appears that the KOM is now being offered in a 29mm width (650b only). Any idea if this version would be more durable than the narrower ones? Was looking at the Asym i29 but they seem pretty heavy. Thoughts?
Joe, I’d be surprised if the durability were meaningfully different.
I’ve been thinking about 29″ KOM i21s or i23s on Hope Pro 4s to run on my AWOL (rigid steel drop bar). I mostly run 32mm file tread Gravel Kings on road, but occasionally break out anything from a 40mm CX tyre to 2.1″ mtb tyres for 4wd tracks and light singletrack. Total rider + bike weight is around 100kg. I’d like to be able to carry a light load off road. Should I be looking elsewhere?