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  1. #1
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    DT Comp Race vs Sapim CX-Ray???

    I have a new Santa Cruz Bronson and am looking at picking up a set of Santa Cruz’s 27.5 Reserve 30 wheels.

    These wheels get rave reviews for their ride characteristics, toted as being one of the best riding carbon wheels out there. But, they’re not the lightest at around 1730-1760g’s

    On Santa Cruz’s website they state that they tested a few different spokes before settling on the DT Competition Race to tune the feel of these wheels.

    I’ve been talking to a wheel builder who states that he can get them down to 1630g’s (w/o tape and valves) by using CX-Ray spokes.

    This seems like the perfect wheelset to me. 30mm inner width, I9 hubs, carbon rim with a lifetime warranty!

    But, will the CX-Rays change the ‘feel’ of ride of these wheels compared to Santa Cruz’s build which uses DT Competition Race’s???

  2. #2
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    The DT Comp Race spoke uses a 1.6mm butted center section. (not dissimilar to WheelSmith DB14 at 1.7 or Sapim Race at 1.5) They're strong, light, and round.

    The CX Rays are also great spokes, but bladed obviously. Very commonly used on high end wheel builds and notably more expensive.

    You haven't provided the number of spokes being used, the lacing patter, or how much you weigh. Despite that, on a bike like the Bronson with tubeless tires on carbon rims, and 150mm of rear travel, I promise you'll never know what kind of spokes your wheels are laced with. (provided they're not dangerously under built)

    It sounds like you're shopping for nice wheels. They will be excellent with either spoke.
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  3. #3
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    Quote Originally Posted by *OneSpeed* View Post
    The DT Comp Race spoke uses a 1.6mm butted center section. (not dissimilar to WheelSmith DB14 at 1.7 or Sapim Race at 1.5) They're strong, light, and round.

    The CX Rays are also great spokes, but bladed obviously. Very commonly used on high end wheel builds and notably more expensive.

    You haven't provided the number of spokes being used, the lacing patter, or how much you weigh. Despite that, on a bike like the Bronson with tubeless tires on carbon rims, and 150mm of rear travel, I promise you'll never know what kind of spokes your wheels are laced with. (provided they're not dangerously under built)

    It sounds like you're shopping for nice wheels. They will be excellent with either spoke.

    Santa Cruz’s Reserve 30 rims are only available in 28 hole. I would imagine these will be laced 3 cross. I’m about 190lbs., closer to 200 all geared up.

    You do make a valid point, on this bike and not being a ‘pro’ of any sorts, I probably wouldn’t notice a difference. But, I do believe I would notice the 100g weight difference. I just do not want to ruin the ride of these wheels which is raved about.

    I have a set of Enve M60/40’s on my 5010 and I battle with hand numbness on that bike.

  4. #4
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    Quote Originally Posted by cobrakillerta View Post
    Santa Cruz’s Reserve 30 rims are only available in 28 hole. I would imagine these will be laced 3 cross. I’m about 190lbs., closer to 200 all geared up.

    You do make a valid point, on this bike and not being a ‘pro’ of any sorts, I probably wouldn’t notice a difference. But, I do believe I would notice the 100g weight difference. I just do not want to ruin the ride of these wheels which is raved about.

    I have a set of Enve M60/40’s on my 5010 and I battle with hand numbness on that bike.
    Many 28h wheels are laced 2x. Depending on the flanges and spokes being used, sometimes 3x is no bueno with 28h.

    Weight wise you're only talking about 50g per wheel (hypothetically, realistically is probably less) and it's not out at the tire where it might possibly make a noticeable difference. Truth is unless we are discussing a 140lb rider using a 19 lb XC hardtail there is no way you're going to notice a 50g difference in spoke weight, especially on a bike with 150mm of rear travel.

    What tires are you using? What do they weigh?

    Lastly if you have hand numbness on your 5010 it's because of fit, not the spokes in the wheels. Most likely your hands are too low or your reach it too long and there's too much pressure on your hands. Try raising the bars/riser bars, new grips, shorter stem, etc.
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  5. #5
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    1.5mm db spoke vs a 1.6mm db spoke. Your weight savings will be no more than 35 grams total.

  6. #6
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    Your wheelbuilder is quoting you weights without tape and valves, on the other hand Santa Cruz gives you weights with tape and valve.
    I did some simulations on two different spoke calculators and the difference between the calculators came under 2g for the total weight.
    I will give you the weights I got with the i30 rims, DT 350 CL Boost hubs, without tape and valve.

    DT Comp Race 3cross - 1668g
    Sapim CX Ray 3cross - 1634g
    Sapim CX Ray 2cross - 1626g

    You are saving 40g at max, and those savings are not even in the rim.

    Honestly I wouldn't do it. But if you like the look and don't mind spend the cash, it's your money, so... .

  7. #7
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    Honestly I’m asking about the ride/feel of the wheelset and weight savings vs price as he will be building these for the same price as I can get the stock Santa Cruz wheelset for.

  8. #8
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    Use DT revolution, far cheaper then the CX
    Ray(Aerolite), same weight and ride.

  9. #9
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    Quote Originally Posted by peabody View Post
    Use DT revolution, far cheaper then the CX
    Ray(Aerolite), same weight and ride.
    Second that. Bladed spokes are only for vanity in the MTB world. Sapim is generally full of **** when it comes to their claims, as DTs and Sapims round spokes are also cold-forged. If you like the look, then cool, but otherwise, Revolutions and Lasers build great wheels and are far cheaper.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  10. #10
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    As far as ride quality, I've built my last four carbon wheelsets with CNspoke 424 that I get from csc for 60/$80 and they ride fine. But at 200lbs I'd use Sapim Race, too bad we can't get those for 50 cents anymore!

  11. #11
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    Laser are the same specs(near) in performance as Rays. I've built Chinese carbons with them. The ride is fine. Never broken one.

  12. #12
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    CX-Ray (and Laser) won't be as laterally stiff. Maybe 10% less than DT Race. At your weight on a 28H trail build, I wouldn't choose a spoke that narrow (or bladed; more surface to collect mud). I'm actually surprised SC didn't opt for standard 2/1.8/2 DT Comp.

  13. #13
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    Quote Originally Posted by alexdi View Post
    CX-Ray (and Laser) won't be as laterally stiff. Maybe 10% less than DT Race. At your weight on a 28H trail build, I wouldn't choose a spoke that narrow (or bladed; more surface to collect mud). I'm actually surprised SC didn't opt for standard 2/1.8/2 DT Comp.
    Where are you getting this information?

    There is no way a complete wheel is 10% less stiff with a CX Ray or Laser spoke compared to a DT Comp Race. That's nonsense.

    A Laser is 1.5 center, a Comp Race is 1.6. If what you say is true, a Comp Race would be 20% less stiff than a normal Comp at 1.8 center section.

    I'm 205 lbs without gear. I ride hard, I ride a lot. I build my own wheels and the last 5-6 wheel sets have been with Sapim Laser spokes. The wheels on my 29+ hardtail, Race wheels, trail 29ers, everything. Not had a single broken spoke and none of my wheels are flexy because of the spoke choice.

    I'd love you to produce some kind of factual information to support your claims. I'm pretty sure SC, and Enve, and every other major wheel manufacturer knows how to build quality wheels. My question is where are you getting your information?
    Last edited by *OneSpeed*; 5 Days Ago at 06:39 AM.
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  14. #14
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    Quote Originally Posted by *OneSpeed* View Post
    My question is where are you getting your information?
    Your post is so combative I'm inclined not to bother. Why ask if you've already decided my response is nonsense?

    Spokes stretch under load in proportion to cross-sectional area. It's 7.07mm^2 for one and 8.04mm^2 for the other. Ignoring the rim, hub, and a half-dozen other factors, you'd expect a 1.6mm spoke to be ~14% stiffer than a 1.5mm spoke.

    To account for everything else, I'd use this:

    https://github.com/dashdotrobot/bike-wheel-calc

    I played around with it last year enough to make the guess above. I don't have it installed at the moment, so my guess could be (and certainly is for some rim and hub combinations) wrong. And maybe the difference is imperceptible to you, and maybe these companies don't want to build stiff wheels. I don't know or care. Ride whatever you want.

  15. #15
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    Well if you're thinking you want bladed spokes to keep track of windup during build you have options. A dot with a sharpie near the nipple or a small tape flag works for me. The Blading is an additional process that adds a small amount of strength. 3.5x the price. Your call. 1600N vs 1500N for Lasers.

  16. #16
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    Quote Originally Posted by alexdi View Post

    Spokes stretch under load in proportion to cross-sectional area. It's 7.07mm^2 for one and 8.04mm^2 for the other. Ignoring the rim, hub, and a half-dozen other factors, you'd expect a 1.6mm spoke to be ~14% stiffer than a 1.5mm spoke.

    To account for everything else, I'd use this:

    https://github.com/dashdotrobot/bike-wheel-calc

    I played around with it last year enough to make the guess above.
    What makes you think that calculator is accurate?

    I think you need to expand on "stiffness". Are you talking about a single spoke deflecting when you put a tension gauge on it or the overall stiffness of a built wheel? The stiffness is determined more by the rim stiffness and bracing angles than what spoke is used.

    Example, If I build a wheel using Comp spokes (1.8) and a Stans Crest rims it's going to flex like hell under my weight. Compare that wheel with Lasers and a Stans Flow rim with Boost hubs.

    By your theory the first wheel should be 30% stiffer when in fact the second wheel will be much, much stiffer in reality.

    My guess is you are misinterpreting the results or have a poor understanding of what makes a wheel stiff, or something?
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  17. #17
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    So Onespeed is trying to sound smart in this spoke discussion but he cant stick with the concept of "ceteris paribus" as even outlined in the original post. The spokes are the only factor in question, always were....

  18. #18
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    Since you'll never actually ride both wheel configurations back to back, you'll never really know if they feel different, so its all theoretical anyway, right?

    Yes, they'll feel different with cx rays/lasers/revs since there is a measurable difference in the spokes. In my opinion, with the rim in question, the difference is so small that most riders wouldn't notice under most circumstances in a blind test.

    CX rays are so expensive that they have a weird side benefit of people feeling WILD differences when using them. Crazy stuff that is beyond reason, like shaving 10 minutes of a 3 mile climb. No one builds a nearly $2000 attractive carbon wheelset and goes "meh".

    For this scenario, psychology plays a bigger role than actual tangible benefits.

  19. #19
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    Quote Originally Posted by Schulze View Post
    So Onespeed is trying to sound smart in this spoke discussion but he cant stick with the concept of "ceteris paribus" as even outlined in the original post. The spokes are the only factor in question, always were....
    Listen guy, I'm not trying to sound smart. I'm just trying to get some clarification and facts to support someones claims.

    Maybe my comparison question wasn't a fair one.

    I have a hard time believing that half of my wheelsets are 30% less stiff than the others and I just don't notice. If you changed any aspect of my (your) bike by 30% it would stand out in a major way. Frame stiffness, tire pressure, whatever.

    You're saying you agree and that Lasers are 30% less stiff (all things equal) than Competition spokes?
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  20. #20
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    According to a basic deflection formula, a 1.5mm cross section spoke has 69.4% the stiffness of a 1.8mm cross section spoke. Damon Rinard's testing showed that a 32 spoke wheel with 2mm vs 1.45mm spokes lost only 11% lateral stiffness. With a stiff carbon rim and a smaller difference between spokes I'd estimate the difference in lateral stiffness between a Laser and Comp to be 2-3%. Between Laser and Comp Race around 1%.

  21. #21
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    Quote Originally Posted by Schulze View Post
    According to a basic deflection formula, a 1.5mm cross section spoke has 69.4% the stiffness of a 1.8mm cross section spoke. Damon Rinard's testing showed that a 32 spoke wheel with 2mm vs 1.45mm spokes lost only 11% lateral stiffness. With a stiff carbon rim and a smaller difference between spokes I'd estimate the difference in lateral stiffness between a Laser and Comp to be 2-3%. Between Laser and Comp Race around 1%.
    Right, If you're using a spoke tension gauge on a single spoke it deflects much more. I was never contesting that, and fully understand. See...

    Quote Originally Posted by *OneSpeed* View Post
    I think you need to expand on "stiffness". Are you talking about a single spoke deflecting when you put a tension gauge on it or the overall stiffness of a built wheel?
    The way I read what Alexdi said I thought he was claiming the complete wheel was 10% less stiff laterally. Looking at his post again he was probably talking about a single spoke, but that sentence is worded poorly and can easily be misread. (obviously)

    That's all I was trying to clear up. I hate it when people post unsupported BS, and I thought that's what he had written. His post lacks clarity.

    Sorry for the overreaction. You cleared up his comments.
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  22. #22
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    Well I meant to say displacement instead of deflection. Typing too fast. For an axially loaded member, d=PL/AE.

  23. #23
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    If CX-Rays are the same price as competition race spokes then go for it. Realistically you will not be able to tell the difference riding wheels with either of these spokes..That is if you did a blind test.

  24. #24
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    I definitely prefer having a stronger spoke on the drive side. I've snapped Laser/Revos there, but otherwise haven't had trouble w/ those light weight spokes in other locations on XC wheels. I also find the wind up of Laser/Revos is problematic w/ the higher tension typically found on the drive side. For XC racing, I'll typically use DT Comp Race or CX-Ray on the DS and then Revo/Laser for the rest of the wheels. I've built some wheels w/ CX-Rays all the way around and didn't find them to be any better or worse (just more expensive.)

    With all of that having been said, why on Earth would you buy a new set of wheels for a trail bike and then pay for new spokes, pay someone else to re-lace them for you, and likely risk voiding the warranty? I'd get it if you were racing and putting these of a light XC bike, but it doesn't make sense to me on a Bronson. For a trail bike, the Comp Race should be ideal.

  25. #25
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    I've snapped lots of spokes including Comp Race's, but have yet to break a CX-Ray. IMHO CX-ray's do ride a bit differently laced to stiff carbon rims. They have a "lively" or "springy" characteristic to them which I like. Of course I'm not smart enough to back that up with any actual data, just my seat of the pants anecdotal feel. While I'm a small sample size I'd also mention CX-ray's seem to come untensioned more frequently than their more substantial brethren in 29'r format. I'm also quite heavy so a bit of an outlier.
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  26. #26
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    CX rays are rolled flat lasers. Its still a 1.5mm spoke, just at 3x the cost.

    I cant feel the difference, even on a road bike with 100psi tires and no suspension. I think its a lot to ask to feel fractions of a mm of deflection/stretch/flex with huge tires and 6+ inches of suspension.

  27. #27
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    Yeah, I can't argue with that. Not sure I've ridden lasers (definitely never built with them), but the comp race's are 1.6 and to me they do ride differently. I have to assume there's more going on than the 0.1mm. Like you said there are so many variables and I can't articulate much less quantify what it is I'm feeling. When I got my first set of carbon wheels right away it was apparent I was getting more trail chatter through the handlebars. Going by feel only it seems I get less of that feedback with CX-rays. Building on that they also seem to deflect more (in a built wheel) in a positive way. The latter is the lively/springy aspect.
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  28. #28
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    This was just shared today by Matthew Ford, a doctoral student at Northwestern:

    https://github.com/dashdotrobot/phd-...hesis_v1.0.pdf

    bicyclewheel.info - Bicycle Wheel Designer

    It's an incredible read if you're into wheel theory and practice. I don't know if he's defended it yet, but the math appears to line up with with his (and Rinard's) empirical tests. One counter-intuitive discovery: additional spoke tension actually reduces lateral stiffness (though increases strength). He also introduces a simple method for characterizing rim properties.

    The site calculator simplifies spoke comparisons. With a sample R460 28H 1.5mm configuration, lateral stiffness is 53 N/mm. At 1.6mm, it's 60 N/mm; the thicker spoke results in a 13% stiffer wheel. With the sliders maxed on rim stiffness (quite unrealistic), the difference is 10%. Both differences would be slightly lower in reality because the calculator assumes a fixed-thickness spoke (rather than a butted spoke with only a central narrowed section).

    Other interesting results (which all assume 100 kg/f spoke tension):

    Spoke Quantity Spoke Diameter Lateral Stiffness Increase Lateral Strength Increase Radial Strength Increase
    28 1.5 0% 5% 10%
    32 1.5 10% 11% 20%
    28 1.6 12% 3% 7%
    32 1.6 23% 10% 16%
    28 1.8 37% 0% 0%
    32 1.8 52% 7% 9%

    These are all numbers for the wheel in aggregate, not the spokes alone. The "increase" columns are normalized to the lowest value for that column.

    If I'm interpreting his explanations correctly, thinner spokes create a stronger wheel because they're more efficient at sharing loads with neighboring spokes. Thicker spokes radically increase lateral stiffness, but it seems to be an open question whether this is desirable.

  29. #29
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    Well that's quite the paper. 137 pages.

  30. #30
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    Quote Originally Posted by alexdi View Post
    With a sample R460 28H 1.5mm configuration, lateral stiffness is 53 N/mm. At 1.6mm, it's 60 N/mm; the thicker spoke results in a 13% stiffer wheel.
    I'll buy that.
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