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So if we reduced the spoke tension of a standard 32 spoked rear wheel to about 50-60kg and locktited the nipples we would have a wheel that would be just as strong as the same wheel with higher tensions (100-110kg) but would have spokes with a significantly longer fatigue life.  Or is that the catch, the wheel at 50-60kg would not be as strong as the wheel with higher tensions. Thank you for your input. Steve Sauter A thought experiment : Take a beam, anchor it half way up a wall so it projects horizontally. Make the beam long and flimsy enough so that it bends to the floor with 100lb on the end. Get a (perfect, tension) spring, say of 1' no tension, and 1'/100lb stiffness. Attach the spring to the end of the beam with a cable to the ceiling. Put 100lb on the end of the beam. The beam will deflect 1'. Now, take an identical spring and attach it to the bottom of the beam and a cable to the floor. Adjust the length of the cables so the beam is horizontal and both springs have 100lb of tension. Put 200lb on the end of the beam. The beam will now deflect 1'. The 2 springs are twice as stiff as one. If you put another 100lb on the end (300lb total), the beam will deflect another 1', or 2' total, because the bottom spring will contribute nothing after it goes slack. If you had set the initial tensions to 150lb, the total deflection with 300lb of load would have been 1.5'. This roughly represents what happens locally at the rim when the load goes high enough to slacken the spoke(s). The spoke(s) in the load area are represented by the bottom spring, the top spring represents the rim stiffness and the other spokes in the wheel. The spoke can only support the rim while it is under tension, the less initial tension, the less load the wheel can support before the rim becomes unsupported. This illustrates only the radial effect, but slack spokes also affect lateral support in a similar way. Another model is that of railroad track and ties. If you remove a tie, the track becomes unsupported over the span, both vertically and laterally. A slack spoke is like a removed tie, where the rail represents the rim.

Besides impact/nick damage, either fatigue may be a problem or the spokes may fail under high radial impacts (potholes) depending on the layup schedules. My guess is, to get the stiffness, they're using primarily uniaxial CF, so these spokes may be very brittle to impact loads. Perhaps the CF spokes may buckle first, it'd take an analysis to determine that. Interesting, can that really be applied accurately to the spokes mavic is using since there are so many different types of carbon and carbon layups? Steve Sauter You'd need to know the materials & layup to accurately predict the spoke behavior, yes. That's always the big unknown with composites. _meta_ls are much simpler.

On Sep 17, 8:23 am, Qui si parla Campagnolo-www.vecchios.com Nope, at least not these days. Hubs are still fairly plentiful and even shimano makes a new/better one for 2008. Rims are too, with DT and Velocity making more models all the time. Hooray for Shimano, goodbye stupid AL 10 speed only freehub. Great thing about boutique is that you can easily justify DuraAce/ Velocity. See honey, they're $800 cheaper than the Mavics, so sos wife let him buy. Too bad the new ti  freehub isn't backward compatible with 7800/7801 hubs..7800/7801 freehubs are even different, as I found out the hard way. Best quote on the R-Sys wheel, Mavic has reinvented the wagon wheel, solid spokes, brilliant. bikesnobnyc iirc. A package of Twinkies to anybody who can guess the material used on ultegra SL to make it lighter. Steel. Where do I send them??  Good for you. Thanks. I will forego the twinks. Raise a glass, that's all. And it really was a guess.

Saw them at my LBS this week, the employees have been singing their praises as they have been using a demo set to try them out. They are supposed to be very light, very stiff, but not particularly harsh to ride. The rims are pretty low profile so not much aero benefit to them. They are also (yikes!) $1400 for the set. Anyone own them yet or had a chance to try them out? Would appreciate any feedback...thanks I got to test ride them for a bit.  I found them to be quite stiff and very responsive. 1400 grams for $1400 seems a touch steep but it is new technology. I would say they are specificly a climbing wheel. I would think that the aerodynamics of these wheels would have to be pretty poor when you are dealing with low profile rims and 4mm round spokes.  The other thing I was a little skeptical about was how the aluminum drive spokes would hold up since they are now at lower tensions.  The reason for the lower tensions was so they could make a lighter rim and because the carbon spokes could handle compression, but aluminum spokes can't.  So in theory radial loads could significantly accelerate the fatigue of the drive spokes since they will not be able to handle compressive loads. compression doesn't cause fatigue, tension does.  if tension is lower, fatigue will be less, other things being equal.  Also, don't nick the carbon spokes or else they will be severely weakened.  According to our mavic rep. they have already had a few cases of broken carbon spokes which they are still trying to determine whether or not they were caused from nicks in the spokes.  I would wait a year before investing in these wheels. so keep them in their bags when not using them - just like mavic say. that's why the bags come with the wheels!  if you nick steel or aluminum spokes, they can break too!- Hide quoted text - - Show quoted text - So if we reduced the spoke tension of a standard 32 spoked rear wheel to about 50-60kg and locktited the nipples we would have a wheel that would be just as strong as the same wheel with higher tensions (100-110kg) but would have spokes with a significantly longer fatigue life.  Or is that the catch, the wheel at 50-60kg would not be as strong as the wheel with higher tensions. Thank you for your input. Steve Sauter there's three reasons we have tension on conventional spokes. 1. tension allows wire spokes to provide compressive support. 2. sufficient tension allows that support to be maintained. 3. sufficient tension allows that support to be maintained with sufficient integrity that spoke nipples don't unscrew. but, excess tension increases fatigue and decreases load capacity of the rim.  and wheel strength does not increase as spoke tension rises above the minimum required for 1, 2 & 3. now, in lateral loading of a dished rear, it's easy to have the non-drive spokes go slack in use.  but if those spokes can withstand compression, and there's no unscrewing, there's no reason to have any more tension on the drive side than is necessary to meet the 1, 2 & 3 just for the drive side alone.  and thus, tension can be reduced.

Besides impact/nick damage, either fatigue may be a problem or the spokes may fail under high radial impacts (potholes) depending on the layup schedules. My guess is, to get the stiffness, they're using primarily uniaxial CF, so these spokes may be very brittle to impact loads. Perhaps the CF spokes may buckle first, it'd take an analysis to determine that. Interesting, can that really be applied accurately to the spokes mavic is using since there are so many different types of carbon and carbon layups? Steve Sauter You'd need to know the materials & layup to accurately predict the spoke behavior, yes. That's always the big unknown with composites. _meta_ls are much simpler. not when you know about them properly they're not!  far from it.