DT Supercomp spokes

[splat]

I read somewhere that these spokes are specifically recommended for disc wheels.

 

Can any clever people tell me why?

[splat]

Is no one clever, or does no one have an answer?

Thicknesses @ the nipple end, middle & J bend end

DT Competetition is 2.0-1.8-2.0

The classic lightweight spoke for all round use

 

DT Supercomp is 1.8-1.7-2.0

The ideal spoke for lightweight Mountain bike wheels, with extra strength to optimise use with Disc brakes

 

Why is the triple butted one better for disc brake wheels?

[Matchstix]

lighter and suppoesed to be stronger than revoltion spokes

stronger where you need it at the j bend. .  most spokes that I have seen breakes there.

this is what I can gather.

 

[Johan Bornman]

I read somewhere that these spokes are specifically recommended for disc wheels.

 

Can any clever people tell me why?

 

It is total bullsh*t. It is just to try and carve a new niche in a market and make standard double-butted spokes look unsuitable for this or that application.

DT Swiss also has spokes for "trekking" upside down riding and reversing. There is nothing wrong with double butted.

 

Triple butted makes the spoke sound better - like triple distilled whisky. However, it simply means there are three diameters on the spoke. Also, now you have to stock special nipples and never get the two confused. A 2mm nipple will screw onto a 1.8mm spoke but strip at high tension. Most bike shops don't go high enough tension, leaving the spoke to strip on the trail at a later stage.

 

Bwah!

 

 

Edit: I hate it when machines sensor my foul language. What I wanted to express was this: b-u-l-l-s-h-i-t.

 

I honestly don't know what the difference is between a euphemism such as "WTF" and the real thing and wish people and machines would stop pretending that an asterisk suddenly cleanses the original expression.

 

 

Johan Bornman2009-10-02 04:15:26

[Matchstix]

thought JB will show up to straighten us out. . 

[Dukeblue]

JB, I completely agree - when people write ****, they actually want to use the colloquial word for fornication. What difference does that make, that is what my brain processes in any ways? WTF?

 

Almost as annoying is the use of smileys as passive agressive tools  (see, you can learn great words from reading the wife's Cosmo on the toilet whilst taking a ****)

 

What I don't get, is why you think double butted is good, but triple butted is BS (hah). Isn't double butted also just a marketing tool? I can't wait for quintuple butted spokes. They will be light, strong and whilst not cheap, offer excellent value for money

 

 

 

 

[splat]

OK, Thanks.

I thought as much. I couldn't understand why a triple butted spoke would be better in any way (apart from weight) than double butted. And why on earth would it be better for disc brake wheels?

 

No wonder so few people stock them.

[Johan Bornman]

Spoke strength is a loaded term and a bit meaningless.

 

Strength in engineering terms is measured in several ways:

 

1) Tensile strength - how much weight can you hang from the spoke before it breaks.

2) Compressional strength - how much weight can you load onto a concrete pillar before it crumbles.

3) Torsional strength - how far can I twist your arm before it breaks.

4) Durability - how many times can I bend a piece of wire before it breaks.

 

Spokes don't require compressional strength or torsional strength (other than to assist the wheelbuilder in preventing the spokes from twisting).

 

Spokes need a bit of tensile strength (there's lots of them so they share the load and are strong enough for even a gorilla) and lots of durability.

 

Durability is a function of the build, the manufacture and the metallurgical treatment of the metal.

 

Double butted spokes are typically 2mm at the thread and elbow and 1.8 or thinner in the centre part (shank). The reason for this is that the loading and unloading of the spoke as the wheel rotates, makes it stretch and unstretch at the thinnest part, protecting the vulnerable thread and elbow. Machine bolts that are for vibrating machines are made the same, the centre part of the bolt is smaller than the ends.

 

A secondary function of double-butted is weight saving. You can't go much thinner than 1.5mm because those spokes won't have enough torsional strength and you won't be able to wind up the nipples when building the wheels. 1.5 mm is already a problem to build.

 

A tertiary function of double butted spokes is they've enjoyed more cold working during the manufacturing process and they're thus handle cyclical stresses better than a piece of steel of the same thickness, that didn't enjoy all the hammering and drawing to get the centre thinner.

 

Most people find it puzzling to see that a thinner spoke (Revolution) can handle more stress cycles by a large margin, than a thicker spoke. This, in spite of it not being as strong (tensile) as a thicker spoke. A bladed spoke has received even more cold working and the results show on fatigue tests - millions more cycles can be had from a bladed spoke.

 

Triple butted is essentially the same, it just introduces a silly size nipple.

 

All this butting and cold working goes to waste if the wheelbuilder doesn't understand that spokes break from metal fatigue and he doesn't know how to eliminate stress risers and crooked elbows.  Very few do.

 

 

Unfortunately DT Swiss makes the butts on their spokes very long and the thin shank is only a small section in the middle of the spoke. SAPIM makes the butt short with a long shank, maximising weight saving. Only DT's Revolution spokes follow the SAPIM model.  

 

 

Double-butting is not a marketing tool.

Johan Bornman2009-10-02 08:19:47

[Johan Bornman]

lighter and suppoesed to be stronger than revoltion spokes
stronger where you need it at the j bend. .  most spokes that I have seen breakes there.
this is what I can gather.

 

 

Not quite. Revolutions and Lasers are 2mm-1.5mm-2mm whereas the spokes mentioned above are only 1.7mm at their thinnest. This means Revolutions have less metal and are thus lighter.

 

As for stronger, see my explanation of strength in the post above.

 

[Dukeblue]

Johan,

 

I am not mechanically inclined, but that was a great explanation! Thanks for taking the time to put it so succintly.

 

The only thing is was wondering about was the think shank - is that like a think tank for inmates?

 

On a side note - have you ever seen the ridges on a Tune hub where they contact the dropouts, and do you know of a possible solution?

 

 

[Matchstix]

 

lighter and suppoesed to be stronger than revoltion spokes

stronger where you need it at the j bend. .  most spokes that I have seen breakes there.

this is what I can gather.

 

 

Not quite. Revolutions and Lasers are 2mm-1.5mm-2mm whereas the spokes mentioned above are only 1.7mm at their thinnest. This means Revolutions have less metal and are thus lighter.

 

As for stronger' date=' see my explanation of strength in the post above.

 

[/quote']

 

I agree with your statements JB

I am only stating the theorie that I think is the reason for the triple butted.

Is the supercomps not lighter than the dt competition? IN theorie the supercomps are are stronger than revolution(not that strenght is an issue) but lighter than competitions.

According to previous thread DT doesnt recommend the recolution spokes for disc wheels(although it is fine to use them)

in your experience where do most spokes break?

 

[rock]

for what its worth I have DT supercomps front and rear with pretty red nipples.......so that means they're the best :-)

 

 

 

rock2009-10-02 06:28:27

[XTC OKE]

johan what is the best

 

sapim or DT?

 

[Johan Bornman]

Dukeblue:  Thanks for pointing out the error. It should of course read Thin Shank.  I'll edit my post.

 

Can't say I have noticed the ridges on a Tune hub. Why are they a problem?

 

Matchstix:  Yes, the supercomps are lighter than DT Competition but at the expense of simplicity. There is no reason at all for a 1.8mm butt. It is like designing a 1.235l  milk bottle.

 

If you want to talk strength, choose one of the options in my explanation, then I can answer your question.

 

The previous thread's story about Revolutions not being suitable for disk brake use was b-u-l-l-s-h-i-t. Full stop.

 

Where do spokes break? It depends on who built them.  Spokes can also break in the thin shank, this happens only if you ride into a stick of something. This is a tension break. Other spokes break from fatigue - always at the elbow. Yet others, where the rim is not designed for large angles, break at the thread. This is a stress crack, the stress riser (starting point) being the first thread on the spoke, hidden inside the nipple.

 

Fatigue cracks at the spoke elbow can almost be eliminated. By carefully building and stress relieving, you can bring these breaks down to one in a few thousand.

 

Spoke thread breaks are more difficult to eliminate and is largely the fault of the rim manufacutrer or the unsuitable hub/rim combination. Large hubs such as PowerTap are an excellent example, as is Rohloff hubs on MTB wheels.

 

XTC OKE: What are the best spokes? We have to compare apples with apples i.e. double-butted with double-butted.

 

Both SAPIM and DT Swiss make excellent spokes from vacuum degassed 18/8 cold-worked stainless steel. Sapim has the better butting process on their standard double-butted spokes since their butts are very small compared to DT's butts. This gives a longer flexible shaft and lighter wheel. Unfortunately the local importer brings them in in road bike sizes only.

 

DT's butts are long. It is just a weight issue and in my eye, an aesthetics issue. I prefer the look of thin spokes, especially a nice road bike wheel built with Revolutions or Laser (Sapim's "REvolution").

 

I have equally good success wrt breakages with both these brands. I have never tried Wheelsmith, which is now also available in ZA.

 

 

 

[Goodbadugly]

"Where do spokes break? It depends on who built them.  Spokes can also break in the thin shank, this happens only if you ride into a stick of something. This is a tension break. Other spokes break from fatigue - always at the elbow. Yet others, where the rim is not designed for large angles, break at the thread. This is a stress crack, the stress riser (starting point) being the first thread on the spoke, hidden inside the nipple." JB.

 

 

 I have read on mtbr that one guy complained that some of the Supercomps failed where the threads started. I have no experience with them. Maybe 2mm vs. 1.8mm a not so good idea?

An idea to create more niche sales like JB said.

Goodbadugly2009-10-04 11:58:17

[bccdnrider]

Check theses guys spoke tech out.

 

http://www.pillarspoke.com/