Curve24disc-9
  • jules

    would you use these for CX?

    • Hmmm… very good question. If they were a little wider, then definitely yes.

      • jules

        literally after typing that I saw an Instagram post by Lisa Jacobs rocking some of these – not sure if same width though
        https://instagram.com/p/5zAyVeSp9O/

        • Lisa’s green and gold puppies are the 30mm x 25mm wide tubular. (also available in a Clincher)

    • Hey Jules,

      Adam from Curve here – As a blanket rule would recommend our 30mm wheelset for CX, they are wider (25mm) and are burlier in design and construction. We have also successfully built these rims in 32 spoke for gravel grinder / tourers who are carrying heavy loads across some pretty gnarly terrain with no issue. So with that said, if you are ‘light’ rider in both style and stature then these could actually be a look in at this specification.

    • harv

      i currently use similar open mould OEM carbon rim built for CX and commuting use – (24mm) built with DT Swiss 240 disc hubs, Sapim CX Ray, 28hole F&R, 3 cross, ~1300g. I bought the wheelset custom made to my spec from Farsport for $1300 landed in Aus, 4wk wait time to build. i run 28mm slicks for commuting and 32mm knobbies for gravel grinding/ CX use. I’ve had the wheels for ~12mths, and have been bombproof, but i am 62kg wringing wet so not exactly hard on wheels!

      • Harv just practical question, do you change your tyres each time for different riding or do you have 2 pairs of the wheels?

        • Disco

          If you even think about racing your annual low grade cross race without at least 2 sets of carbon deep section wheels, well you are just not trying hard enough. And that’s saying something.

  • Oldan Slo

    “You definitely need sound spokes,” said Steve. “Sapim CX-Rays have … very little flex width ways, so are great for light disc builds.”

    Seriously?

    Width ways stiffness of the spoke is of no importance to wheel performance because the spokes are relatively free to rotate around the spoke hole and the nipple around the rim at the other end. They both act as simple supports so there is negligible bending moment in the spoke.

    • jules

      agreed. spokes act purely in tension. wheel flex is limited by spoke tension (i.e. higher spoke tension, more resistance against wheel flex) – with tension being a property of how much you tighten the spokes and completely independent of spoke properties. spoke tensile limit will determine whether/when the spoke breaks under tension.

      • Rosco

        Sorry if I am paraphrasing you incorrectly Jules, but after a certain point, spoke tension makes bugger all difference to a wheels lateral stiffness.
        The big determining factors are bracing angle (which is pretty poor these days with 11spd freehubs) and the spokes ability to resist stretching under load. Theres not much than can be done about bracing angle except for offset rims.
        However more spokes = greater ability to resist stretching under load. But thicker spokes also do the same. Hence Mavic wheels feel quite stiff; well at least the ones using steel spokes. The heavy chopstick spokes just resist stretch much better than tiny flexy spokes like Sapim.
        The last wheel build I did was a 16/20 set up with sapim CX-rays. It was rubbish. But after a long search for DT Aero Comp spokes, my wheelset was vastly improved. A 20/24 set up would be better, but I’m amazed that CX-rays are used so widely (probably because there are more weight weenies than people who race).

        • jules

          we’re discussing different things. all of those you wrote are true, but I meant “all those things being equal.. ”

          as a matter of interest though, I wonder how much spokes stretch along their length and how much this contributes to wheel flex/deflection? I would have imagined that drive-side spokes – being near vertical – don’t need to stretch much in order for the rim to move towards NDS (cos of small angle = negligible amount) and the NDS spokes are being put into compression.

      • winkybiker

        Again, sorry if I am mis-reading this, but I agree with Rosco. Once the spokes are tight enough to not be competely unloading (i.e. going to less than zero tension) when at their lowest tension (when they are under the hub) then more tension does not result in a stiffer wheel. More spokes and/or thicker spokes make for a stiffer wheel, as does less dish (better angle on the drive side).

        • jules

          disagree. the spokes play a key role in limiting rim deflection (wheel flex) relative to hub (although I’m not entirely convinced about spoke thickness). yes, those latter parameters are influential – no argument. but spoke tension is too. increasing tension means increasing the force with which the spokes will act against external forces (cornering, weight of rider/bike) acting to deflect the rim.

          if there is say 90 Newtons of force acting laterally against the rim (tyre contact patch) through cornering, then this is resisted by the lateral (horizontal) component of spoke tension. fundamentally, this resistant force is proportional to spoke tension (force). the spokes are really more like springs, with the spring stiffness a function of spoke tension. the spring/spoke deflection will be proportional to the spring stiffness (spoke tension).

          • winkybiker

            Nope. Once the wheel is tight enough (for the spokes to not go slack when under the hub or otherwise at their minimum tension), then additional spoke tension just offsets the spoke tension in opposing spokes (diametrically and laterally). The effective spring constant (which is a numerical constant that relates load and deflection) and therefore elongation and deflection under load won’t change. The amount the spokes elongate (and then shorten) as the loading cycle varies (due to rotation and side-to-side rocking) is a function of the spring constant only, and not of the pre-load. Spokes are linear in response over the working range of the wheel. Of course, a wheel that is so loose that the spokes go to zero tension when under minimum load will not be stiff at all as the spokes can’t take compressive leads (Mavic Tra-Comp notwithstanding).

            Things that can make the effective spring constant higher (and the wheel therefore stiffer) are more spokes, thicker spokes and shorter spokes (smaller wheels, bigger flanges and/or fewer spoke crossings). Heavier rims also help by spreading the loads across more spokes.

            • jules

              I think I agree with you. my only question – as below – is if the spoke spring co-efficient is a constant. if you’re saying it is then I have no knowledge otherwise so I’ll concede and change my mind on previous hypothesis :)

        • jules

          you’ve got me thinking about this.. in my assessment of spokes as acting similar to a spring, I’d have to concede tension doesn’t affect stiffness to the extent spokes act as a simple spring (F = k.x). however if they act non-linearly, i.e. the incremental force required to extend the spring by a given increment increases as the spring is extended, then I’d contend my original assertion holds true.

          i’m unsure which is the case though, now..

  • dllm

    135mm versus 142mm hub spacing
    … :)

  • John

    Is that an upside down bike in the background of the first photo? Blasphemy!

    • JH

      I consider the valve caps even worse than that.

  • dynatella

    I have mtb wheels that weigh less than that, for a road bike these aren’t even entry level light.
    .

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