Options for spoke replacement

[annirak]

You have a point there. Now that I look, I can see the short butt on at least one spoke. I wonder if they aren't those stupid DT-Swiss "superstrong" (whatever they call them) spokes which are 2mm at the thread, 2mm in the centre and 2.5 or 3mm at the bend? Opeeee! where's your vernier?

I'll measure again tonight!

[edit:] I keep wondering if alternative materials, such as carbon fibre, would be better for durability, but then I read about carbon fibre spoke failure.

 

[Yellow Saddle]

I'll measure again tonight!

[edit:] I keep wondering if alternative materials, such as carbon fibre, would be better for durability, but then I read about carbon fibre spoke failure.

Naaah, steel is the best in this application. The durability of a spoke is just about infinite, if it is the right spoke for the job and fitted properly. The last part of the installation, the stress-relieving, can actually be considered the last manufacturing step which without, the spoke is not ready for use. Unfortunately this bit is left out. I have spokes in a set of wheels which have done far in excess of 200 000 kms before I stopped logging my miles about 8 years ago. These are DT Revolutions in a 28-spoke wheel. In other words, the thinnest spokes possible in a wheel that's borderline "standard" in terms of spoke count. Nothing beats wire for such applications because the two fixation devices at the ends are built in and needn't be bolted on afterwards using glue, aluminium bits and tricks.

 

[Yellow Saddle]

Fascinating thread.

Taking it off at a tangent is it common to break a spoke at the Jbend? In 30 years I can't think I've broken a spoke at bend. Plenty at the thread end.

If your spokes break at the tread end, it usually means they are straight-gauge spokes. In other words, the weakest and thinnest part of the spoke is the thread end. If the spokes are double-butted, the weakest (measured in tensile strength) is the slender centre shank. Because it is smooth and without nicks, that flexes an infinite number of times without failure - like a spring that just goes on and on and on. However, if the spring starts to work inside the thread, you have a stress riser and traveling stress crack that very quickly breaks the spoke without it even approaching its point of permanent deformation (stretch).

Is it common to break a spoke at the J-bend? Yes, that's the weakest point, not matter what the configuration. The reason for that is that residual stresses inside the spoke, left there after the bend, should never be combined with cyclical stresses. These residual stresses (stretching at the outside of the bend and compression on the inside of the bend) should be removed after building by stress relieving. Stress relieving is a well-understood concept in engineering but wheelbuilders don't get it.

 

[annirak]

You have a point there. Now that I look, I can see the short butt on at least one spoke. I wonder if they aren't those stupid DT-Swiss "superstrong" (whatever they call them) spokes which are 2mm at the thread, 2mm in the centre and 2.5 or 3mm at the bend? Opeeee! where's your vernier?

Aha! They are 1.9/1.9/2.3 by my vernier! 2.3 at the J-bend. Looks like a case of “super strong” spokes

 

[Yellow Saddle]

Aha! They are 1.9/1.9/2.3 by my vernier! 2.3 at the J-bend. Looks like a case of “super strong” spokes

Yup. Ridiculous concept but easy to sell to a gullible force of mechanics who see the 0.3 as added strength instead of built-in weakness.

A thick wire bent at 90 degrees has far more internal stresses than a thin wire bent at 90 degrees. That's why flexible electrical cord is made up of very thin strands of copper wire which lasts a very long time even though it is bent and flexed and folded and rolled up throughout its life.

 

[rogerzilla]

They usually break at the elbow. They usually break at the thread if the lacing pattern isn't the right one for the wheel (e.g. 36 x4, or x3 with a large-flange hub and small wheel) or if someone laces the rim the wrong way round, with LH flange connected to RH rim holes and vice-versa. The latter is very easy to do by mistake with some rims, where the holes all look to be *almost* on the centre line. In any case, there should be no soft curve where the spoke enters the nipple, since this just allows it to flex in use. There needs to be a hard kink. Or use Sapim Polyax nipples.

 

[T675Rich]

Blimey and I thought I had issues with spokes breaking.

 

[mickle]

What's the size of your rim?

(@Fnaar )

 

[Ming the Merciless]

What's the size of your rim?

(@Fnaar )

You'll be asking about the width of their bottom bracket next.

 

[Yellow Saddle]

They usually break at the elbow. They usually break at the thread if the lacing pattern isn't the right one for the wheel (e.g. 36 x4, or x3 with a large-flange hub and small wheel) or if someone laces the rim the wrong way round, with LH flange connected to RH rim holes and vice-versa. The latter is very easy to do by mistake with some rims, where the holes all look to be *almost* on the centre line. In any case, there should be no soft curve where the spoke enters the nipple, since this just allows it to flex in use. There needs to be a hard kink. Or use Sapim Polyax nipples.

Polyax nipples. I've done the measurements. They have no more swivel than a DT Swiss nipple. Sapim also managed to fool customers.

 

[Tom B]

If your spokes break at the tread end, it usually means they are straight-gauge spokes.

They were. Usually on cheapish, but 34/36 spoke count wheels.

I've had my more recent wheels rebuilt by a retired LBS owner and wondered why he was pressing on the rim when I watched him. He used new straight gauge spokes but they've been spot on only breaking (again at the thread) when subjected to external factors (a squirrel and a derailleur)

In other words, the weakest and thinnest part of the spoke is the thread end. If the spokes are double-butted, the weakest (measured in tensile strength) is the slender centre shank. Because it is smooth and without nicks, that flexes an infinite number of times without failure - like a spring that just goes on and on and on. However, if the spring starts to work inside the thread, you have a stress riser and traveling stress crack that very quickly breaks the spoke without it even approaching its point of permanent deformation (stretch).

Is it common to break a spoke at the J-bend? Yes, that's the weakest point, not matter what the configuration. The reason for that is that residual stresses inside the spoke, left there after the bend, should never be combined with cyclical stresses.

I've spoken to one of my more portly friends who breaks spokes more regularly and he advised they fail near the bend.

My wheels usually die from flatspotting at some point.

 

[Yellow Saddle]

They were. Usually on cheapish, but 34/36 spoke count wheels.

34-spoke wheels?

I've had my more recent wheels rebuilt by a retired LBS owner and wondered why he was pressing on the rim when I watched him. He used new straight gauge spokes but they've been spot on only breaking (again at the thread) when subjected to external factors (a squirrel and a derailleur)

There's pressing on the rim and pressing on the rim. Which type was he doing and how?

I've spoken to one of my more portly friends who breaks spokes more regularly and he advised they fail near the bend.

The least durable (not weakest) place on a spoke is at the bend, on the right hand side on the wheel on the inbound side of the hub flange. Weight and torque do have a negative influence on top of all the other factors.

My wheels usually die from flatspotting at some point.

A well-built wheel does eventually die from either hub failure or rim failure. The spokes are the last to go.