sapim cx ray spokes?

[dezmtber]

As the title has anyone used them for trials?

there black and available in all the sizes i need for a good light 24" wheel build.

the sapim site has a lot of test results putting them up as very strong. But i just cant see how they can be.

[AdamR28]

They are 'strong' in terms of cyclic loading and tensional strength per mm^2, but they feel flexy in a trials wheel.

[dezmtber]

I will stick to plain 2mm spokes. Thanks for the advice

[Blake]

non disc side front wheel if you think you're edgy enough

[dave33]

I have these on 3 or 4 wheels they are strong light and I differently don't find them flexy at all.

John Webster was the person who told me about these and he seems to thing they are stiffer. Kenny Belaey had them on his bike to.

Iv never snapped any but I have snapped the standard sapim spokes which are shit compared to DT.

[Maxx]

I have ridden these for like 6 months on two Try-all K2 wheels, and I never had any lateral/radial trueness problems. You also need a spoke holder to prevent spokes to twisting.

But don't forget the key of a good and long lasting wheel is a good building.

A good wheel building is accomplished by :

- good tolerances on lateral/radial/dish trueness, but not too high ! It is completely useless to have 0.01mm tolerances !

- high and uniform spokes tension (if your wheel is dished you'll have different tension on freewheel side and non freewheel side). You need to have a tensiometer for that thing, past results have proved that "30 years experience wheelbuilders in bike shops" are wrong when they say they check the tension with the hands.

- stressing the wheel many times during the process until the wheel doesn't go out of true when stressing.

[dezmtber]

I was going to rebuild my wheels with them.

currently have hope hubs on viz 24" singlewall rims. Since building them they have required no trueing or tensioning.

plan was to rebuild on the cx ray spokes with sapim alloy nipples and hm nipple washers.

but was going to use radial front non disc side.

i am just a bit worried don't wanna spend a fortune on spokes if there not up for it.

[Al_Fel]

I saw Phil Williams do a decent sized drop gap at Lee Quarry with these spokes in his back wheel and his hub touched the rock he was landing on haha. His wheel completely folded. Not one spoke snapped which I thought was pretty weird. I wouldn't recommend them for trials personally.

[Blake]

I was going to rebuild my wheels with them.

currently have hope hubs on viz 24" singlewall rims. Since building them they have required no trueing or tensioning.

plan was to rebuild on the cx ray spokes with sapim alloy nipples and hm nipple washers.

but was going to use radial front non disc side.

i am just a bit worried don't wanna spend a fortune on spokes if there not up for it.

I'd sort that out if you're wanting a lighter wheel, get light hubs and you can still run strong spokes. You'd end up with a similar weight as if you'd used these silly spokes

[Maxx]

I forget to say, Gilles Coustellier rode (maybe still ride) Dt Swiss Aerolite on his bikes (which are the equivalent for Cx-Ray, but more expensive).

I personally prefer to gain weight on spokes rather than on the hub : you can easily replace a spoke, and that's also cheaper to replace a spoke than a hub ...

[AdamR28]

they feel flexy in a trials wheel.

To back this up with some simple physics...

Plain 2.0mm spokes are 3.141mm^2 cross sectional area.

'Normal' 2-1.8-2mm double butted spokes have a cross sectional area in the centre of 2.54mm^2.

'Triple buttted' 2.0-1.5-2.0 spokes are 1.767mm^2 - if you can't tell the difference between these and the 1.8 or 2.0 spokes when riding then you probably don't need expensive spokes in your wheels...

Even if CX rays were rectangular (which they aren't, they are a blade), their x-sec area would be 1.98mm^2. Guesstimating the profile being a nice elipse (from memory this is approximately right) puts them around 1.7mm^2.

They are not as stiff as 'normal' spokes, and approximately as stiff as triple butted.

Sapim state the weight of 64 x 260mm CX Rays as 272g, and the Laser 2.0-1.5-2.0 as 273g. So the weight and the stiffness are pretty much the same. This is why they are are AERO spokes, their advantage is for aerodynamics, not stiffness or weight...

[trialsalot]

This description made me moist Adam! Nice!

[dave33]

They are 'strong' in terms of cyclic loading and tensional strength per mm^2, but they feel flexy in a trials wheel.

To back this up with some simple physics...

Plain 2.0mm spokes are 3.141mm^2 cross sectional area.

'Normal' 2-1.8-2mm double butted spokes have a cross sectional area in the centre of 2.54mm^2.

'Triple buttted' 2.0-1.5-2.0 spokes are 1.767mm^2 - if you can't tell the difference between these and the 1.8 or 2.0 spokes when riding then you probably don't need expensive spokes in your wheels...

Even if CX rays were rectangular (which they aren't, they are a blade), their x-sec area would be 1.98mm^2. Guesstimating the profile being a nice elipse (from memory this is approximately right) puts them around 1.7mm^2.

They are not as stiff as 'normal' spokes, and approximately as stiff as triple butted.

Sapim state the weight of 64 x 260mm CX Rays as 272g, and the Laser 2.0-1.5-2.0 as 273g. So the weight and the stiffness are pretty much the same. This is why they are are AERO spokes, their advantage is for aerodynamics, not stiffness or weight...

here we go again... with your simple assuming.

i really dont want to do sound like im arguing with you here Adam but people seem to take what you say on here as fact. you have compared the area of the different spokes listed and assumed they are all made from the same materials.

you also failed to notice the extra forging process required that bladed or aero spokes go through, giving them additional stiffness. just whats needed in trials with the extreme acceleration and sudden braking

directly from sapim site figures say it all really.

Technical specs Weight: (64 pcs x 260 mm lg) 272 g

Quality: AISI 302

Strength on middle section: 1600 N/mm2

cxray

Technical specs

Weight:

14G (64 pcs x 260 mm lg) 363 g

Quality: Stainless

Strength on middle section: 1300 N/mm2

Dimensions

Length: 135-310 mm

Diameter: 14G 2.0 - 1.8 - 2.0 mm

butted

I have ridden these for like 6 months on two Try-all K2 wheels, and I never had any lateral/radial trueness problems. You also need a spoke holder to prevent spokes to twisting.

But don't forget the key of a good and long lasting wheel is a good building.

A good wheel building is accomplished by :

- good tolerances on lateral/radial/dish trueness, but not too high ! It is completely useless to have 0.01mm tolerances !

- high and uniform spokes tension (if your wheel is dished you'll have different tension on freewheel side and non freewheel side). You need to have a tensiometer for that thing, past results have proved that "30 years experience wheelbuilders in bike shops" are wrong when they say they check the tension with the hands.

- stressing the wheel many times during the process until the wheel doesn't go out of true when stressing.

this is also a really good point.

[AdamR28]

Strength isn't the same as stiffness though?

Even it was, using those numbers they are still ~20% less stiff than 2.0-1.8-2.0s.

[Joe Papasnap Maher]

i really dont want to do sound like im arguing with you here Adam but people seem to take what you say on here as fact.

Because, unlike you, he's not a tool :$

[dave33]

Strength isn't the same as stiffness though?

Even it was, using those numbers they are still ~20% less stiff than 2.0-1.8-2.0s.

was that a question? not sure what your getting at ? but i do remember it was youngs modulus for stress and strain, but then again cx rays arnt round so can you still use that?

maybe you should do some calculations for comparison between the cx rays and the laser 2.0-1.5-2.0 as you seem to like that stuff... even you dont know the material properties but you can guess that?

i like how you ~ that key about.

[AdamR28]

Yeah it was a question. I always thought stiffness was not the same as strength, but you posted strength data so I thought it might have been otherwise.

Yeah you can still use Youngs Modulus, governs all materials which exhibit elastic properties.

Well there's no point as we don't know the stiffness values of the material. We have a strength value but - from what I remember - it's not relevant. I had a look here but can't find the same grades as the spokes: http://matweb.com/search/QuickText.aspx?SearchText=steel%20stainless

With the cross sectional area being vastly smaller, I can't see how they will be of similar stiffness, plus from riding wheels built with them I would say that's the case.

[dave33]

Yeah it was a question. I always thought stiffness was not the same as strength, but you posted strength data so I thought it might have been otherwise.

Yeah you can still use Youngs Modulus, governs all materials which exhibit elastic properties.

Well there's no point as we don't know the stiffness values of the material. We have a strength value but - from what I remember - it's not relevant. I had a look here but can't find the same grades as the spokes: http://matweb.com/search/QuickText.aspx?SearchText=steel%20stainless

If the cross sectional area is vastly smaller, so I can't see how they will be of similar stiffness, plus from riding wheels built with them I would say that's the case.

well im glad you agree on that, i did some maths my self 3.14x1.15x0.5 =1.805mm^2

and with the added forging to the material stiffness to weigh comparison will be greater than the 2.0-1.5-2.0 you already stated.

normal spokes to you must be 2mm plain gauge where as i always go for 2-1.8mm

[*gentlydoesit]

2 peneth..

I take it the spokes are flat not round

I always attribute strength to tensional, and stiffness to tortional, if the cross section is wider across the tortional area and in parralell with said tortion force, I can't see it not being stronger, unless its made of chocolate. Of course being weaker on the narrower side, but is the load applied on that axis?

English version (as that confused me when I read it back)

Ever tried to bend a ruler the wrong way? Same thing

[AdamR28]

i did some maths my self 3.14x1.15x0.5 =1.805mm^2

That's great but it bears no relation to the cross sectional area of a CX Ray spoke.

I was giving the CX Rays a bit of extra 'beef' as a fudge factor to help their cause, but if you want to do it that way the x-sec area comes out at 1.55mm^2: http://www.sapim.be/spokes/aero/cx-ray

2 peneth..

I take it the spokes are flat not round

I always attribute strength to tensional, and stiffness to tortional, if the cross section is wider across the tortional area and in parralell with said tortion force, I can't see it not being stronger, unless its made of chocolate. Of course being weaker on the narrower side, but is the load applied on that axis?

English version (as that confused me when I read it back)

Ever tried to bend a ruler the wrong way? Same thing

I getcha, yeah. The spokes are in tension though when the wheel is torqued up (pedalling force), hence the chat about cross sectional area.

Any side loading is mostly (nearly completely) constrained in this case by the spoke tension as well, rather than the resistance to bending of the spokes themselves.

[dave33]

To back this up with some simple physics...

Plain 2.0mm spokes are 3.141mm^2 cross sectional area.

'Normal' 2-1.8-2mm double butted spokes have a cross sectional area in the centre of 2.54mm^2.

'Triple buttted' 2.0-1.5-2.0 spokes are 1.767mm^2 - if you can't tell the difference between these and the 1.8 or 2.0 spokes when riding then you probably don't need expensive spokes in your wheels...

Even if CX rays were rectangular (which they aren't, they are a blade), their x-sec area would be 1.98mm^2. Guesstimating the profile being a nice elipse (from memory this is approximately right) puts them around 1.7mm^2.

They are not as stiff as 'normal' spokes, and approximately as stiff as triple butted.

Sapim state the weight of 64 x 260mm CX Rays as 272g, and the Laser 2.0-1.5-2.0 as 273g. So the weight and the stiffness are pretty much the same. This is why they are are AERO spokes, their advantage is for aerodynamics, not stiffness or weight...

if thats not how you work out the area iv gone wrong some where or you have got some doggy spokes or lastly you can't measure

i took checked a spoke i have here 2.3mmx 1mm.

That's great but it bears no relation to the cross sectional area of a CX Ray spoke.

I getcha, yeah. The spokes are in tension though when the wheel is torqued up (pedalling force), hence the chat about cross sectional area.

Any side loading is mostly (nearly completely) constrained in this case by the spoke tension as well, rather than the resistance to bending of the spokes themselves.

you also assumed all wheels have the same spoke tension. spoke tension is the biggest variable you missed out on and the biggest relation between how stiff and flexy the wheel feels.

[trialsalot]

This is like that staring match sketch on big train!!

[dezmtber]

The main reason i was looking at these spokes is they come in black and in lengths of 240, 236 and 220

so i can have black spokes and not have to cut and roll new threads.

i know halo do black in most sizes but i found the coating chipped off and rust comes out

if there are other options i would prefer a round spoke at a cheaper price. As the cx rays are going to cost around £100 for the wheel build.

[Luke Rainbird]

Dave calls Adam out on approximating figures and making a few relatively valid assumptions, posts up some lengthy drivel whilst pointing out he's not sure whether Young's Modulus applies and people continue to dignify him with replies?

Whatever next? Perhaps he'll play the "I'm an engineer' card. Tune in next week to find out...


Dez, that seems a fairly hefty price tag for something that's going to give minimal weight saving (assuming that' your main aim?). As mentioned there are likely other places on the wheels you could save some weight which'd probably be worth going for first - probably a safer bet to push things elsewhere and save some money in the process before taking things to that level later on.

[dezmtber]

The weight is just a bonus. I just cant find any good black 220mm spokes