XC Racing Rims?

Discuss light weight issues concerning mountain bikes & parts.

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Lelandjt
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by Lelandjt

I want to build a really light 29" Boost wheelset that isn't too delicate for technical XC (think Breck Epic). I'm definitely gonna use 28 CX-Rays, probably on J-bend DT 180s. I've been searching for rims and the Nox Skyline (345g) is currently looking best. What else do you like?

by Weenie


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LeDuke
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by LeDuke

Lelandjt wrote:I want to build a really light 29" Boost wheelset that isn't too delicate for technical XC (think Breck Epic). I'm definitely gonna use 28 CX-Rays, probably on J-bend DT 180s. I've been searching for rims and the Nox Skyline (345g) is currently looking best. What else do you like?


Teocalli front, Skyline rear.

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youngs_modulus
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Location: Madison, WI USA

by youngs_modulus

I've had great luck with Light Bicycle rims. If I were building a set of XC wheels now, I"d use these:

https://www.lightbicycle.com/XC923-asym ... -rims.html

But I'm curious: why the heck would you use CX-Rays on a mountain bike wheel instead of Sapim Lasers? There's no substantial aero advantage off-road, and Lasers are just as light as CX-Rays. They're also a a third the price.

So why CX-Rays?

tonytourist
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Location: 93306

by tonytourist

Ergott built me a set of Nox Skylines on Carbon Ti hubs- I think they are sub 1270g, but I haven't weighed them and forget what he told me they were before tape. (I want to say 1262 g)
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Lelandjt
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by Lelandjt

youngs_modulus wrote:I've had great luck with Light Bicycle rims. If I were building a set of XC wheels now, I"d use these:

https://www.lightbicycle.com/XC923-asym ... -rims.html

But I'm curious: why the heck would you use CX-Rays on a mountain bike wheel instead of Sapim Lasers? There's no substantial aero advantage off-road, and Lasers are just as light as CX-Rays. They're also a a third the price.

So why CX-Rays?

No wind-up. Once you've built and trued wheels with bladed spokes you don't want to go back because of their "wrench flats". I'm "industry" and don't pay much for CX-Rays in return for telling everyone to buy CX-Rays. If you wanna see expensive spokes price out DT Aerolites. Even at EP I don't buy those anymore.

Yeah, I've got my eye on that LB asym rim and also LB's 10g lighter, $100 cheaper non-asym XC rim.
Last edited by Lelandjt on Thu Feb 16, 2017 6:40 pm, edited 2 times in total.

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Lelandjt
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by Lelandjt

tonytourist wrote:Ergott built me a set of Nox Skylines on Carbon Ti hubs- I think they are sub 1270g, but I haven't weighed them and forget what he told me they were before tape. (I want to say 1262 g)
Image

Are Carbon Ti hubs lighter than DT 180s? That wheel with 180s was looking like 1300g by my estimation .

youngs_modulus
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Location: Madison, WI USA

by youngs_modulus

Lelandjt wrote:
youngs_modulus wrote:
So why CX-Rays?

No wind-up. Once you've built and trued wheels with bladed spokes you don't want to go back because of their "wrench flats". I'm "industry" and don't pay much for CX-Rays in return for telling everyone to buy CX-Rays.


Ah! That makes perfect sense. Yes, Lasers wind up something fierce. I've learned to twist past my desired rotational position and then counterrotate to take the windup out of the spoke. It's imperfect, but I've had a lot of practice, so it's not so bad.

Also, the fact that you're not paying retail makes CX-Rays a much more reasonable choice. For two 28-spoke wheels, CX-Rays cost consumers a ~$115 premium over Lasers. But if you're not paying an extra $2/spoke for CX-Rays, the convenience could easily be worth it.

I admit it pushes my buttons when people use CX-Rays on mountain bike wheels because they're "stronger" (not true, despite Sapim's scientifically illiterate claims) or, worse, "stiffer." I mean, people can use whatever parts they like, but I find it depressing to watch people extra for imaginary benefits. The low-windup properties of CX-Rays are not imaginary, of course.

Lelandjt wrote:Yeah, I've got my eye on that LB asym rim and also LB's 10g lighter, $100 cheaper non-asym XC rim.

Heh. To be perfectly honest, I'd probably get the symmetric rim too. The width at the bead is only 1 mm narrower on the symmetric rim, and the cost savings is substantial.

Have you considered using Extralight hubs instead of DTs? I know pro deals on DT stuff can be fantastic, but if you don't need Centerlock rotors, the Extralights (at least the front hub) might make sense. 68 grams!

Gullholm
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Location: Sweden

by Gullholm

Just wanted to ask where you've found 180s with Boost spacing, I was sure they didn't make them?

Another rim option is Duke Lucky Jack, around 340-345g (confirmed), 24,8mm internal and asymmetrical. Haven't ridden them but looked very nice, both the profile and when it comes to finish.

A friend is considering MCFK clinchers, haven't seen them irl yet though but if you wouldn't mind the price they also look like very nice rims.

Edit: Plus one on the Extralights too, been so happy with mine that I got another set for my new wheels.

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Lelandjt
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by Lelandjt

Thanks for the rim and hubs suggestions. I haven't seen 180s in Boost yet but I was gonna call DT in Grand Junction and ask. I need these wheels by late May. I wanted to use XTR centerlock rotors but I may go with a lighter 6 bolt like Formula.

Gullholm
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by Gullholm

I see, fingers crossed then. Makes sense that they'll come out eventually. Actually ran 180s for a couple of years and they are indeed great quality hubs, so except for the slight weight penalty over the Extralites you can't go wrong with them.

Same thing with Formula rotors, light but feels surprisingly solid and also quite silent. I had their older 2-piece rotor (2009 version I think) and they're still going strong, so I guess the newer ones are at least as good if not better.

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Lelandjt
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by Lelandjt

Okay, it looks like Extralite Cyber Boost hubs, CX-Rays, and the non-asym 22mm LB rim comes to 1200g, 1670g with Nox or Duke rims. I wanted to stick with J-bend spokes for the easy replacement aspect but these days I keep labeled tubes of extra spokes for all my wheelsets in my traveling toolbox anyway.

Gullholm
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Location: Sweden

by Gullholm

Maybe slightly optimistic with those weights, based on the wheels I've built lately with Extralites I'd estimate a 360g rim would make them come in at around 1245-1250g and a 345g rim then at 1215-1220g.

Still, that's a really good weight for 29" clinchers!

Personally I had good luck last year with CX Super spokes and will run them this year too, but maybe that'd make the wheels a bit too "delicate" for you. 17% lighter than CX-Ray.
And yes, go for straightpull - looks better too. :beerchug:

tonytourist
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by tonytourist

Lelandjt wrote:Are Carbon Ti hubs lighter than DT 180s? That wheel with 180s was looking like 1300g by my estimation .

I didn't even look into the 180s so I don't know. My build is 28/28, CXRays, aluminum nipples and the mentioned rims.
Need to get the rest of the build done! :beerchug:

UpFromOne
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Location: Olympic Nat'l Park, WA

by UpFromOne

Duke Lucky Jack = bang for the buck. Gotta love asymmetric spoke holes.

by Weenie


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Lelandjt
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by Lelandjt

UpFromOne wrote:Duke Lucky Jack = bang for the buck. Gotta love asymmetric spoke holes.

Extralite lists spoke lengths for their hubs based on rim ERD. How would you modify that length for the 2.5 - 3.5mm offset rims?

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