Spoke me a spec? No, spec me a spoke

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  • Spoke me a spec? No, spec me a spoke
  • Premier Icon Northwind
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    Got a set of lightbicycle carbons just about to arrive, and a set of DT240s for them to make friends with. Going in my hemlock, so 160mm travel front, does assorted everyday riding, quite a lot of enduro racing, some uplifts etc. I’m not that fast, but I’ve been known to ride into trees at high speed so they’ve got to be durable, but still weight is a consideration, I do like a light wheel.

    So… what spokes? I was just going to go supercomps, I’ve got on well with them in my Traversees and these’ll have a full spoke count so will be stronger. But often people say Sapim D-lights and CX-Rays are equivalent, and they’re a fair bit lighter. The CX-Rays are supposed to have a better fatigue life too which is the only place I can really fault the supercomps.

    Or, o’course, could beef up to Comps. And other brands are available I’m sure but I don’t know anything about them.

    What do you reckon, o internet?

    Gee76
    Member

    For similar weight of Supercomps but a lot cheaper go for ACI Alpina’s (cheap at cycle basket or sdeals!).

    I’ve gone for Revs on my last couple of carbon builds (26″ and 29″) and have been ok so far. The rims are pretty stiff (as your porbably aware) and so have gone 28 holes too.

    Hopefully they’ll stay straight as I went ally on the nipples too.

    Premier Icon tomaso
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    So you are not fast ride into trees and like light wheels. Expensive carbon rims it is then! DT Alpine or CX Rays would be my choice for big bucks performance

    Premier Icon Northwind
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    Yeah, I’m mid-tabley in most races but not in the same race as the fast boys, no delusions of grandeur.

    I’ve got Revs in an XC wheelset and they’ve been fine but the wheels are a lot flexier. Low spoke count to be fair but I wouldn’t want that on a big bike. Think that’s a weightweenie too far.

    Tom_W1987
    Member

    Sapim Races. My Hope 2’s laced to 32 hole LB wide rims still weighed 1600 grams.

    I lost 400 grams in weight over flows but that wasn’t what I noticed most – it was that the levels of stiffness felt more like one of my old bmxs. Then again, I tend to overbuild things. My goal has always been to get as close to DH levels of performance in as light a package as possible. As opposed to building as light a bike as I can with a token nod towards downhill ability.

    I seem to remember Sheldon Brown made the comment that stiff rims plus a low count of flexy spokes actually led to a much flexier rim than one with a soft rim laced to strong spokes.

    Currently thinking of building an Enduro 29er. My heart says yes, my head says spend far less and get a Capra. If I do build the Enduro, I’m going to go with the 35mm Derby rims laced to 36 hole Pro 2s. I’ll make some of the rotating weight up by running a 1.5 ply Schwalbe Rock Razer on the rear/a single ply on the front and run Saints or V4s to get braking power with 180mm rotors instead of 203.

    Candodavid
    Member

    Rock Razer not available in 29″

    Tom_W1987
    Member

    26 and 27.5, 29-inch from summer 2014

    Damnit, I miss having a nice bike. Going to have to wait a while before I can start ordering bits.

    Looking into this as well for my next wheels (LB 29er / 35mm also) You might find this interesting…http://www.noxcomposites.com/wheel_building. According to the Nox guys, spoke guage is a long way down the list of what makes a wheel stiff:

    1) The rim stiffness
    2) The number of spokes
    3) The spoke bracing angle
    4) The gauge of the spokes
    5) The lacing pattern

    Also this article compares spoke guage in discussion of stiffness: http://speedbloggen.com/2012/06/wheels-again-and-math/

    – DT straight 14 gauge – 2.0mm diameter, yields 3.14 mm^2
    – DT Revolutions – 1.5mm diameter, yields 1.77 mm^2
    – DT Aerolites – .9mm x 2.3mm, yields 2.07 mm^2 (assumed rectangular area)
    – Sapim CX-Rays – .9mm x 2.2mm, yields 1.98 mm^2 (assumed rectangular area)

    His conclusion: if you really want stiff, get plain guage – not much difference between the others. Note: some flex in the spokes may make a stronger wheel as it’s absorbing impact that would otherwise be taken in the hub or rim.

    You mention your supercomps had fatigue problems? I’m surprised, as the only DT spokes I’ve ever broken through fatigue went after 5 years or more (comps) and I thought that was pretty reasonable. I’ve used revs since and never had one break. (I’m quite a “light” rider though, and don’t tend to break stuff).

    Will be interested to hear what you decide on.

    Premier Icon Northwind
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    I should put that more in perspective re the supercomps- they’re in a set of very well used Roval Traversees, which are a sub-1600g wheelset with delusions of being burly all mountain wheels. So they’ve had a stupidly hard life and were always marginal for suitability- just not strong enough for my big bike, now retired to my hardtail. I don’t hold it against them at all and I’d be happy with them but, still, I think I’d like just a little better.

    Interesting article that. I’m not obsessed with teh stiffs, generally as long as things are stiff enough, I’m happy. I reckon wheels can work better with a bit of give tbh. So my XC wheels give away a lot of stiffness for lightness, which is fair enough but wouldn’t work in this bike. The Traversees certainly aren’t stiff, but are stiff enough not to really bother me. My Fulcrum Red Zones are noticably stiffer and it does feel nice sometimes.

    But I’m not going to sacrifice everything for a super-stiff wheel I don’t think. Just something sensible- sensible strength, sensible weight, sensible durability, sensible stiffness.

    Tom_W1987
    Member

    You may have assumed that when wheels rub against the chainstay, fork or cantilever brakes, it is a symptom of flexy wheels. In reality, the situation is more complicated than that. This is because lateral stiffness is affected by two major parts of the wheel; the rim stiffness and the spoke system stiffness. Our carbon rims provide a very high level of rim stiffness, so much so that they can literally overpower low spoke stiffness and this can actually amplify lateral deflection at parts of the rim away from the lateral loading point (the ground). In other words, with all other things equal, carbon rims can increase the rubbing against your chainstays, fork or cantilever brakes! It’s a bit counter-intuitive, but this effect is due to our carbon wheels not conforming or bending when subjected to lateral loads, so the effects of low spoke stiffness are actually amplified by the stiffness of the rims. In contrast, a lightweight aluminum rim conforms as lateral loads are applied, and this deformation masks the chainstay rubbing effect

    http://www.noxcomposites.com/wheel_building

    I once read the same thing from Sheldon. Just can’t find the article. Not a physicist so can’t decide if it’s bollocks.

    Tom_W1987
    Member

    Our standard builds use 32 Sapim CX-Ray spokes, which is an ideal combination of low weight and high enough spoke stiffness for most riders to minimize lateral deflection. If you weigh more than 200 lbs, are a powerful rider on a single speed, or a very aggressive rider, you might want to consider a thicker gauge spoke, but since spoke gauge is number 4 on our list it isn’t something we recommend for most riders. Feel free to contact us to discuss a custom build spec.

    From the link. 🙂

    Definitely going to go with 36 holes for the 29er build, or at least on the rear.

    Premier Icon aracer
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    jimification wrote:

    Also this article compares spoke guage in discussion of stiffness: http://speedbloggen.com/2012/06/wheels-again-and-math/
    – DT straight 14 gauge – 2.0mm diameter, yields 3.14 mm^2
    – DT Revolutions – 1.5mm diameter, yields 1.77 mm^2
    – DT Aerolites – .9mm x 2.3mm, yields 2.07 mm^2 (assumed rectangular area)
    – Sapim CX-Rays – .9mm x 2.2mm, yields 1.98 mm^2 (assumed rectangular area)

    Except the latter spokes aren’t rectangular x-section, and given the CX-Rays are forged from a Laser which has the same dimensions as a Rev (which should also be obvious from the fact the have almost identical weight), both of them actually have pretty much the same x-section area as the Rev. What is also missing from that list is something like a DT Comp or Sapim Race which has significantly more x-section area than anything other than the PG, so will build a stiffer wheel than them.

    Here is some real world testing – e compares stiffness with different spokes, but unfortunately doesn’t compare directly with the difference rims make http://sheldonbrown.com/rinard/wheel/index.htm

    Tom_W1987
    Member

    http://people.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

    That paper from Duke University seems to support spoke gauge having a considerable impact on rigidity. I need to read it properly instead of skimming it, it’s to late now.

    Will end up going OCD over 2 cross vs 3 cross, seeing as two cross offers better lateral rigidity and 3 cross offers better torsional rigidity. Great.

    Tom_W1987
    Member

    I reckon wheels can work better with a bit of give tbh.

    The articles I linked you to seem to think you won’t feel any difference in vertical compliance. Hence I’d go for as much lateral and torsional stiffness as possible.

    Let the suspension do the work as it has proper damping circuits, undamped flex has no use in the vertical wheel when you have suspension.

    Hob Nob
    Member

    CX on my 29″ Derby wheels for the Enduro – i’ve got some Enve’s built with Rev’s too which are also fine.

    I’d be careful with what you build them with, you can build a 26″ carbon wheel ‘too stiff’ IMO. My old bike was slower, and harder to ride with the stiff carbon wheelset (stiff wheels, frame & forks). There is a bit of info floating around about the Enve sponsored DH riders running lower spoke tension because they find the wheels too stiff too. Made the bike really hard to ride on off camber, chattery & rutted trails.

    I certainly wouldn’t want my 29″ wheels any stiffer, although they are better than the floppy Roval noodles that came with the bike, which live on my HT now 🙂

    Hob Nob: You might be right about some compliance being useful. However, spoke tension should have no effect on wheel stiffness (perfectly logical to think it does but from everything I’ve read, it doesn’t), so not sure about the Enve DH thing…

    Just grabbing the rim and pulling it towards the frame / fork on a few bikes here, it’s quite shocking how floppy 29er wheels are compared to 26. Very generally, they seem to deflect about twice as far. (all same spec wheels – Crests, revs, 32h)

    Tom: Yes, Comps are the middle ground missing from that. Agree with you on 2cross / 3cross angst!

    Also, I’m another “non-physicist” (and too lazy to research properly) but would assume cross-sectional area is more relevant than he makes it out to be…I would have thought the relationship between CSA and “stretchiness” would be a square or something (ie: twice as thick = 4x as stiff, or something like that)

    DT78
    Member

    If it helps I used revs on my 29LB rims, on a scale, doesn’t feel flexy at all and they have been put through their paces. 85kg rider.

    Yetiman
    Member

    My 29er rims are being built with pro2 evo hubs, 32h, and DT Super comp Spokes. Not light, not heavy….somewhere in between. hoping to have them built and on the bike for next weekends GT gathering.

    goodgrief
    Member

    Northwind, if you’re in Innerleithen today or from monday night onwards you can have a gander at mine, built with sapim race spokes.

    DT78: that’s useful, cheers.

    From the link aracer posted: (http://www.sheldonbrown.com/rinard/wheel/index.htm) “Standard” rim, 32h, revolutions deflect 11% more than plain guage spokes. Given the fact that the choice might, more realistically be between comps and revs, you’re probably talking more like 8% deflection difference. Then include the fact that the carbon LB rims are likely quite a bit stiffer than the ali rim he was using and the difference in spoke stretch seems quite negligable (to me, at least).

    Based on all that, I’ll probably go with Revs. I already blew my weight budget on the 35mm LB rims anyway (over the XC ones – 420g each vs 365g) so need to keep it light as poss everywhere else.

    Expecting it to come out something like this:

    35mm LB Carbon hookless 29er rims, 420g x2 = 840g
    64 x DT rev = 330g
    64 x DT ali nips = 20g
    DT 240s rear hub with 36t = 255g (without skewer)
    Lefty front hub = 117g

    Total = 1562 That’s 50g each heavier than my current 29er crests, which feel lovely and light but a bit flexy.

    Premier Icon aracer
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    hob wrote:

    I’d be careful with what you build them with, you can build a 26″ carbon wheel ‘too stiff’ IMO. My old bike was slower, and harder to ride with the stiff carbon wheelset (stiff wheels, frame & forks). There is a bit of info floating around about the Enve sponsored DH riders running lower spoke tension because they find the wheels too stiff too. Made the bike really hard to ride on off camber, chattery & rutted trails.

    Given low spoke tension simply makes the wheels weaker rather than less stiff, than tends to confirm the suspicion that’s all a load of rubbish. Explained well in the nox composites article linked above – which is the best scientific explanation I’ve ever seen from a manufacturer.

    jimification wrote:

    Also, I’m another “non-physicist” (and too lazy to research properly) but would assume cross-sectional area is more relevant than he makes it out to be…I would have thought the relationship between CSA and “stretchiness” would be a square or something (ie: twice as thick = 4x as stiff, or something like that)

    You get that sort of relationship for bending, but for spokes you’re just concerned about stretching them, and in that case it’s just about the amount of metal available as there’s nothing complicated going on. Think about stretching one rubber band and then stretching two – you wouldn’t expect it to be more than twice as hard, and all you’re doing when doubling the x-section area is adding another rubber band.

    His conclusion: if you really want stiff, get plain gauge – not much difference between the others.

    I don’t understand this.
    Butted spokes always break at the thread or the bend, never at the thin bit in the middle.
    Doesn’t that mean that plain gauge spokes are just extra weight for no extra strength ?
    Or am I confusing tensile strength with fatigue life, or something like that ?

    aracer: thanks that’s a good explanation. Will double up on the revs (2 per hole!) 😉

    MTG: Yes, though plain guage spokes have more material, they are apparently, no stronger. In fact, butted spokes are theoretically stronger than plain guage, due to the manufacturing process used on them (forging etc). However, I’ve always broken spokes at the thread anyway and I don’t know if that area is any stronger on butted spokes. I’d guess they are certainly no weaker there, though.

    The benefit of thicker spokes isn’t strength, it’s stiffness, though from what I can see, thicker spokes don’t add *that* much stiffness compared to the weight they add and you might be better off “spending” that weight on a beefier rim if you’re looking to build a stiffer wheel.

    Premier Icon aracer
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    wrote:

    His conclusion: if you really want stiff, get plain gauge – not much difference between the others.
    I don’t understand this.
    Butted spokes always break at the thread or the bend, never at the thin bit in the middle.
    Doesn’t that mean that plain gauge spokes are just extra weight for no extra strength ?
    Or am I confusing tensile strength with fatigue life, or something like that ?

    On a basic level you’re confusing durability and stiffness – in this case the durability is also fatigue life rather than strength. The actual strength of the wheel in terms of resistance to big hits is also improved by the increased stiffness of PG spokes as in that sort of situation the spokes tend to be unloaded and it’s the rim which fails rather than the spokes.

    Your comment is one of the reasons I’m always dubious about the durability advantages of CX-Rays, where the forging supposedly increases the fatigue resistance, as it’s only the centre section which is forged, not the threads and bend.

    Premier Icon aracer
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    jimification wrote:

    aracer: thanks that’s a good explanation.

    8) – I did have to think for a bit for a good analogy – I do always enjoy these sort of discussions and trying to explain science stuff to non scientists (which is an extremely good exercise in how well you actually understand things).

    Tom_W1987
    Member

    Aracer, what do you think of the idea that stiff rims can basically overwhelms the spokes? What kind of build would you go with to stop this from happening? (26 and 29)

    I’ve never ridden a bike and thought to myself that it was to stiff, my carbon rims laced to 32 hole hubs with Sapim races were a revelation. I had a hell of a lot more control in high speed turns and through rock gardens, more feeling at the edge of grip through the bars as well. Everything just felt more controlled and predictable really.

    Tom_W1987
    Member

    Does the flange diameter of the hubs have an effect on stiffness?

    Premier Icon aracer
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    Tom_W1987 wrote:

    Aracer, what do you think of the idea that stiff rims can basically overwhelms the spokes? What kind of build would you go with to stop this from happening? (26 and 29)

    Interesting idea, not one I’d come across before reading it in that article, but it all makes sense. All you can really do if you’re concerned about it being an issue is make your spoke build as stiff as possible – 32 2x PG spokes, hubs with flanges as wide as possible. How far you go with that depends on how big an issue you reckon it will be – I’d suggest that the recommendations on that site above are likely to be good, but then for reasons I’ve already explained I’m dubious about their recommendation to use CX-Rays when Comp/Race spokes undoubtedly provide a stiffness advantage.

    Not something I ever thought I’d be that worried about as I used to be a lightweight racing snake, wheels on the ground type rider and used Rev/Laser in my wheel builds. But nowadays I’m a bit heavier and ride unicycles off road, getting more air than I ever got on a bike (which is where my interest in wide carbon 29er rims comes in) – 36 spoke PG builds are routine for uni wheels, though I’ve used Comp spokes for mine, and will probably go with 32 of those 2x when I get a lightbicycle rim (would use 36 if that was a drilling option).

    Flange diameter has a small effect with 2x as it increases the triangulation. With 3x where the spokes are tangential to the hub, the difference is negligible as the spoke length remains almost the same.

    Premier Icon davosaurusrex
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    Whilst we’re on the subject and I’m too lazy to research it what are the advantages and disadvantages of 2x compared to 3x? Is 3x more usual? Just took my rims to the Lbs and they recommended 3x, said it’s a stronger build, true?

    Premier Icon Northwind
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    Well I am none the wiser but thanks all 😆

    I’ve read elsewhere that PG wheels tend to be less durable, as the reduced elasticity means they lack survivability- a “softer” build can deform more without sustaining damage. Sort of like earthquakeproofing buildings, you don’t make them incredibly strong, you make them so they can wobble without falling over. #

    No idea if this is true mind but that’s what I was referring to with the possible usefulness of flex in wheels, rather than trying to create a suspension effect btw.

    Premier Icon aracer
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    Northwind wrote:

    I’ve read elsewhere that PG wheels tend to be less durable, as the reduced elasticity means they lack survivability- a “softer” build can deform more without sustaining damage.

    They are less durable from the perspective that the spokes will fail from fatigue sooner. This is because spokes tend to fail at threads and bends as mentioned above, and these parts of PG spokes are subjected to higher forces because the spokes as a whole stretch less under loading.

    Not really quite the same as you’re imagining – in terms of durability to impact a less stiff build is actually a bad thing as the wheel will tend to fail at a given linear deflection, and you reach that deflection at lower load with a less stiff wheel.

    I’ll try and give a better explanation if you’re still struggling with that…

    Oh and dsr, I’m still thinking about the crossings thing – I may have been taken in by the linked article and need to work out how the forces are working. 3x is certainly the standard, if nothing else because the forces at the hub are better balanced.

    Tom_W1987
    Member

    Any more thoughts on crossing Aracer? Which is more useful for us mountainbikers, lateral or torsional rigidity? Surely lateral rigidity would give us more stiffness in bermed corners or when we are leant over, whilst torsional stiffness would give us better resistance to deflection through rock gardens?

    I can’t decide between the two builds

    A) 36 hole Hope Pro 2’s + Sapim Race + Derby Rims (3 cross pattern)

    B) 32 hole E-thirteen TRSr Hubs (wider hub spacing and taller flanges) + Sapim Race + Derby Rims (2 cross pattern)

    The reviews seem to indicate that the aluminium e-thriteen wheelsets are ridiculously stiff just with 28 holes, so maybe they are onto something with the hub design? Or do you think an increase in spoke count just over 18 percent will have more of an impact?

    What impact would a mixed lacing pattern have? Eg 2 cross non drive side on the back? Some people recommend that pattern if you are going to mix crosses, for mountain biking wouldn’t it make more sense to have the 3 cross on the disk side?

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