Min-Maxed-Metal: WTB KOM Light & Tough Rims
Sometimes, when it comes to bicycle parts, the absolute truth doesn't really matter in the shop or on the trail. Like, for example, what way the spoke heads face in your hub flanges. I've seen two near brawls on the subject - one drunken and one sober - between wrenches I respect and appreciate. But I've had wheels built both ways and a blend of the two, and it's one of those things that I appreciate you may feel strongly about, but I couldn't give two shakes.
On the other hand, my spoke heads are always going to be facing one way or the other. I'm sorry, but even if it was provable that direct-pull spokes are better in every way than a classic j-bend, you can keep them. Some things are worth hanging on to just because they are. And given that the only selling feature companies use in favour of direct pull spokes is stiffness, well, I'll take my noodly wheels, thank you. How bloody stiff do you want your wheels to be?
WTB's KOM rims are remarkably unremarkable in this regard. Are they stiff? Are they flexy? Neither. Under this 190lb rider, with 32 spokes, whether mounted to a 160mm travel full suspension bike or on my fully rigid single speed, they just are. Are what? A perfect blend of stiffness, weight, durability, price, ease-of-inflation, tubeless reliability, and a plethora of width options. It's a really nice package for 100 USD per rim.
I've been riding two pairs of KOM rims for months: one pair of i40 rims with 2.6"-3.0" tires, and one pair with an i40 front and i35 rear with 2.6 - 2.8 tires up front and 2.3 - 2.8 tires for the i35 on the back. The rims are all laced up with Sapim butted spokes and TLC brass nipples and built by my friend Dumpster Bear (thanks Dumpy-B!).
Standard procedure for an NSMB wheel review is that we don't use any sort of insert during the test period but I made an exception - which involved a lot of removing and installing CushCore - for this process because I don't ride my rigid bike without inserts for suspension. When running the wheels on my Marin I never had inserts installed and when riding them on my Waltworks I always had some combination of CushCore Plus & Pro.
For the insatiably curious, here's a tire breakdown:
- Alpine Trail: Front (no insert): 2.8" WTB Vigilante Tough, 2.6" Vigilante Tough, 2.35" e13 LG1, 2.6" Bontrager SE5.
- Alpine Trail: Rear (no insert): 2.6" Vigilante Tough, 2.35" e13 semi-slick.
- Waltworks: Front-Rigid (CushCore): 2.8" Vigilante Tough.
- Waltworks: Front-Suspension (no insert): 2.8" Vigilante Tough; (w/ CushCore): 2.6" Vigilate Tough
- Waltworks: Rear (CushCore): 2.8" Vigilate Tough, 2.6" Vigilante Tough, 2.6" Bontrager SE2, 2.6" Teravail Cumberland.
This probably sounds strange, but a fair amount of the time I was running a 2.8" tire on the i35 KOM on my hardtail and a 2.6" tire on the i40 KOM on my Alpine Trail. This winter I'll be moving a Bontrager G5, a serious min-max tire contender, to one of the i40 rims to compare the profile to the nominal i29/i30 rims that are coming with most bikes and wheels.
One of the selling points I often hear for carbon rims is that they never need to be trued because the rim itself has so much structure. Certainly, the few sets of carbon wheels I've tested have needed less routine maintenance than aluminum rims for the same application so I'll agree there's some truth to that. I've needed to turn the spoke key a few times on all four wheels. Interestingly, more so when they've been run without inserts.
But, the flip side is I know a lot of folks with carbon wheels who break spokes like they're made of dried pasta, and aside from obvious crash damage, that's not an issue I've had with any of the aluminum wheels I've tested and continues to be true for the WTB KOM models.
Tough vs Light
I can't provide an apples-to-apples comparison of the KOM rims because I've been running the Tough version on the rear and the Light version on the front for both sets. It just makes sense. Internally, the KOM Tough version uses dual support beams between the inner and outer walls to reinforce the rims. The Tough version comes in a range of internal widths - 25, 29, 35, 40, & 45mm - and WTB sells this as their Enduro/Gravity option.
Comparing i40 rims, the KOM Light drops about 50 grams but the difference becomes smaller as the rims get narrower. These lose the I-Beam construction but honestly, while I've dented a few front rims, for my riding the kind of "oops" it would take to potato-chip a KOM Light rim is going to do the same to the Tough. The Light version is available in the same range of internal widths and also adds an i21 option for offroading your gravel bike.
I'd be running inserts on my own bike anyways, so I can be easily swayed on whether two KOM Light rims makes sense in getting back 100 grams or whether two KOM Tough rims makes sense since at that point weight doesn't even matter. Oh, bicycle philosophizing.
I have had another KOM fan suggest to me that at 220lbs he notices a stiffness difference between the KOM Tough & Light options in an i29 size. That's on both an enduro bike and a hardtail and if it's happening with the i29 I can only imagine it scales to the wider rim options.
I've certainly noticed when wheels are exceptionally stiff: the Reynolds carbon rims I've tested; Mavics with bladed aluminum spokes; Industry Nines with their aluminum spokes mated to carbon hoops. The few set of Enve wheels that I have tried. Sure, they're stiff. As with handlebars, I don't really see that as a benefit for any mountain bike application whether it's slamming gnarly trails on a 6" bike or trying to survive an outing on my rigid. I'm not de-tensioning my spokes or otherwise actively seeking wet-noddle-rims it's just that, as long as the rims take a beating, I'm simply not out seeking any increase in stiffness over options like these WTB KOM rims.
Ignoring inserts for a moment, the story of the day is lifetime warranty on carbon rims and I've had some interesting discussion - usually centered around Chris King hubs - about upfront cost vs. lifetime investment. How many rims can an alloy rim rider wreck before they could have just bought carbon? The math is complicated by brand-to-brand comparisons. For some riders a two-year, no questions asked replacement warranty is probably the winning value. For others, a lifetime replacement policy where they have to pay for spokes, nipples, and wheel builds probably balances out for the best. For the vast majority of mountain bikers in the world it probably doesn't matter either way nor does it likely matter if the rims are laid up plastic or extruded aluminum.
Once a rider is running massive inserts, long travel, lower pressures, and tough-as tires, I frankly don't see any reason not to stick with aluminum rims. I'm wary of riders who claim to appreciate carbon's stiffness improvements - especially you folks breaking spokes all the time - but hey, whatever works for you. Riders who aren't racing uphill and never wreck wheels? These build up plenty stiff.
In a typical min-max conclusion cop out, if you can afford carbon, and want carbon, ride carbon. Just maybe don't wax poetic to me about all the benefits you perceive unless you fit that narrowing window of riders smashing trails without inserts ("just add more pressure", right?). If you're sticking with aluminum, whether it's price or application, absolutely check out Wilderness Trail Bike's KOM rim options. It's an option I rarely hear thrown around locally, but over two sets I'm happily riding and recommending them.