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  1. #1
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    WTB KOM 29" Rim - wheel build review

    Because there's little information on WTB's newer KOM rim series, I thought I would add a review from a mechanic and wheel builder's perspective. I'll add my thoughts as a rider once I've had a chance to ride them for a few hundred miles or so...

    After much deliberation and a decision to not use a carbon rim, I finally landed on the WTB KOM 29" alloy rim - the goal was a sub-1700 gram 29er wheel set after using a tried and true 2000 ish gram set of Kings/Flows for everyday riding, and having extremely bad luck with a set of low spoke count system wheels. I wanted something in the middle that would be good for race day, yet reliable for moderately aggressive descending or every day use.

    DT Swiss got the vote for weight, serviceability, and reliability in the hub department - 240s c-lock, thru axles:

    WTB KOM 29" Rim - wheel build review-dscn6937.jpgWTB KOM 29" Rim - wheel build review-dscn6938.jpg

    The rims came in 12 grams of one another, fairly light actually:

    WTB KOM 29" Rim - wheel build review-dscn6934.jpgWTB KOM 29" Rim - wheel build review-dscn6935.jpg

    I have access to a Phil Wood spoke cutter and have since switched to using Wheelsmith spokes as they tend to cut and roll very nicely and consistently. For this build I went against my usual brass only rule for mountain wheels and went with a nice blue alloy Wheelsmith nipple and prepped the spoke threads with Rock 'n' Roll nipple cream. The project pre-lacing:

    WTB KOM 29" Rim - wheel build review-dscn6939.jpg

    After lacing, I weighed both wheels individually before the build:

    WTB KOM 29" Rim - wheel build review-dscn6941.jpgWTB KOM 29" Rim - wheel build review-dscn6942.jpg

    Weight goal achieved! Front 767g, Rear 879g, Set 1646g - quite svelte but hopefully dependable as well.

    I've built a lot of Stan's products over the years and usually end up with a decent set of wheels, but I never liked how the Arch EX built up, and the Flow's while a great set of rims, are just heavy, great for training and descending, but a little bit of a bear on extended climbs. The KOMs built up with a strong grade of B+ The tension on the front wheels drive side was a little lower than I would have liked, and there was one flaky spoke that was doing odd things at the spoke bed. Still easily a passing grade over all. The rear went smoother and more predictable. 115 Kg on almost all drive side spokes and most non-drive were evenly distributed around 100 Kg. I'd love to build a few more sets up, better than the Arch EX, not quite as stable as a Flow EX...

    but... the real review is in the ride:

    WTB KOM 29" Rim - wheel build review-dscn6944.jpgWTB KOM 29" Rim - wheel build review-dscn6945.jpg

    After the shake down ride, they get a quick and enthusiastic, YES. Not quite as stiff as my lovely Flows, however the acceleration and weight will more than likely make up for it. These will see racier tires with more PSI than I typically run for fun trail riding, but that was the plan. So far I'm very happy. I plan on abusing them on one of the longest descents on the east coast tomorrow and I will update this thread with a longer term review of the rims and wheels. Thanks!
    My one says BRAP!

  2. #2
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    Thanks for the write-up. Great photos, too. I'd be interested to hear how they fare long term. I was looking at these rims to build a light wheelset but there are reports that the KOMs are a bit fragile.

  3. #3
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    Any issues mounting the Maxxis or Schwalbe's on the rims?

  4. #4
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    The rear went smoother and more predictable. 115 Kg on almost all drive side spokes and most non-drive were evenly distributed around 100 Kg.
    How can it be possible?
    240CL have 100/60% tension distribution, so with 115kg on drive side, you should be at 70kg non drive side.

  5. #5
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    Quote Originally Posted by Mac_Aravan View Post
    How can it be possible?
    240CL have 100/60% tension distribution, so with 115kg on drive side, you should be at 70kg non drive side.
    I was thinking the same thing. Something isn't quite right with those numbers.

    I've built half a dozen sets or so of the KOM rims and like them a lot. I think the people who've had durability issues are the ones who believed the inital WTB marketing that these were 'enduro' rims with strength equal to a carbon rim and they were indestructible, etc. There's no beating physics - these a light-ish XC/trail rims, not burly AM/Enduro rims. However, I think they strike a really nice balance of weight, stiffness, and width.

    If I were building myself another set of alloy rim'd MTB wheels, it would be with the KOMs.

  6. #6
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    Quote Originally Posted by Rhialto View Post
    Thanks for the write-up. Great photos, too. I'd be interested to hear how they fare long term. I was looking at these rims to build a light wheelset but there are reports that the KOMs are a bit fragile.
    I'm sticking to some higher pressures to hopefully avoid any rim damage. thanks!

    Any issues mounting the Maxxis or Schwalbe's on the rims?
    Not really. I've taken to simply removing the valve cores on all my tubeless set ups upon the initial inflation. No issues that way. I think the Schwalbe's tend to be the fussiest but w/ no valve that hook right up.

    How can it be possible?
    240CL have 100/60% tension distribution, so with 115kg on drive side, you should be at 70kg non drive side.
    Yep. I was thinking front when I posted that, just flat out wrong sorry. Wishful thinking but your numbers are the reality. I'm going to throw them in the stand later today to check how the last 3 rides have effected them.
    My one says BRAP!

  7. #7
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    What specifically about the Arches bothers you? Not a critical question, just a curious one.

  8. #8
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    Quote Originally Posted by coombs View Post
    What specifically about the Arches bothers you? Not a critical question, just a curious one.
    They have been inconsistent, I have seen and built some that tension up nicely and I've had to send some back because the inner wall must of had some inconsistencies. This is no knock on the product in general and it's a universal acceptance that a lighter rim will inherently be more challenging to work with.

    At the end of the day? I want another option I can refer my customers to - some of them have had issues with Stan's products that I haven't experienced. So far I think the KOM rim is a nice alternative to the Arch EX...
    My one says BRAP!

  9. #9
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    Front wheel with actual deflection reading after 3 fairly rocky rides averaged 110-120 Kgf disc side, and 80 - 90 Kgf drive side. Rim was within 1 mm laterally. I'm using a Park Tool TM-1 so yeah...

    Rear wheel 100 - 110 Kfg drive side. 60 - 80 non-drive, meh. so more realistic numbers wheel builders (instead of plucking from the air or wishful thinking), rim was within 1.5 mm laterally. Just checking them both out with tires on thus far.

    In other words, I'm happy so far. I feel like they have a nice and lively feel largely due to the weight but without being overly whipy in corners. I'm probably 170 lbs with gear and am playing with higher PSI as I've damaged some rims recently. I'm around 28 psi rear, and 25 psi front. For racing I'm sure it's the right answer. For fun, I like a LOT less of course it's all dependent on tire volume and now, rim selection...

    As an aside the engagement on the DTs isn't as lightening quick as I'm used to with Kings/I9s but damn do they roll quick. I was hoping that they would come with the updated ratchet but I don't believe they did. There was more than once when I clumsily shifted gears or pedaled out of something techy that the hub gave me that knocking sound that I'm just not accustomed to. Not a big deal. I'll take reduced drag over hub engagement at least for the purposes of these wheels. Obviously these are my first DTs, always lusted, never purchased. They nice.

    I'll post more in a few months. I have a few endurance races coming up this summer...
    My one says BRAP!

  10. #10
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    Plume, thanks for this post. I was going to ask which hubs you had experience with, but post #9 explains it, cool. Keep us updated.

  11. #11
    Chris Bling
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    I have been on a set of KOM's since the beginning of the year and have been very pleased. I recently built me up another set for my new Canfileld Yelli Screamy a little over a month ago and have been oh so pleased!

    I raced on them at a local Enduro race and just returned from a trip down to Southern Utah where I grew up. After one especially gnarly trail, I stepped off the bike and spun the back wheel expecting to see some carnage. To my surprise, I spun the wheel and it was still dead true.

    These light rims have impressed me to no end. I have no problem pushing the hardtail into rocks and drops now. They have my stamp of approval.

    Don't know if anyone knows yet, but WTB is coming out with a KOM i25 (25mm internal width) with 29er weights ~460g per rim. Cant wait!!!
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  12. #12
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    Quote Originally Posted by dustyduke22 View Post
    Don't know if anyone knows yet, but WTB is coming out with a KOM i25 (25mm internal width) with 29er weights ~460g per rim. Cant wait!!!
    That's gotta be a typo right? The 23mm 29er versions I've built were all right around 460g, I'd be surprised if the 25mm versions were the same weight.

    WTB originally said the 23mm would be like 420g, but after some testing they added some beef for the production rims.

  13. #13
    mtbpete
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    The WTB 29in Frequency i25's I just built weighed 557g and 565g. 100g is a lot of weight to take off of the rim, but it can be done. I image the profile depth on the KOM will be a lot shorter than that of the Frequency.

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