.

[Johan Bornman]

 

I must say that the LBS I went to for the spokes had no idea what spokes to sell me as a replacement' date=' I took the broke spoke with and they scratched around through many boxes and came back with a suitable replacement that I could see was a lot thinner but the right length so I said rather get be thicker than thinner if you don't have the same size.

As a lay person it is easy to get sold some old junk that has been lying around the shop for year,s I wouldn't  know any different unless I measured them with the vernier.

What do you guys suggest I do with that wheel, does it need a rebuild or can I save it with spoke replacements and trueing again?
[/quote']

 

In order to calculate the length of a spoke you need to know:

 

1) Effective Rim Diameter (ERD)

2) Spoke Hole diameter in hub.

3) Spoke circle diameter in flange

4) Number of spoke crossings.

5) Distance of flange centre to centre of hub.

6) Number of spokes in the wheel.

 

This is then plugged into a mathematical formula that calculates the length of a line in space.

 

As you can imagine, not many bike shops can do this or conversely, not many customers walk into a bike shop armed with that information. Most customers just walk into a shop, asking for a spoke for their blue mountain bike. Most bike shops rely on a table listing some of the most popular combinations.

 

There's nothing wrong with spokes that have been sitting on a shelf for years. They don't age and they don't change into new models each year. Further, spokes are sold in quantities that don't correspond with the number of spokes in a wheel and therefore bike shops build up old stock as the years go by.

 

Ironically, the thinner spoke is the better one. It would have been thinner in the centre and thicker at the two ends, giving it more flex there and thus protecting the vulnerable bend and thread.

 

I think your wheel can be saved and built into a solid, reliable wheel. Find a wheelbuilder that can determine if any of the current spokes will break imminently and knows how to stress relieve spokes after a build. There is nothing wrong with that hub or that rim, it's the build. Unfortunately a poor build compromises spokes.

 

Good luck with your wheel.

 

Johan Bornman2008-10-06 23:05:21

[dirtrider]

Johan I can not read anything when your text is so small !!! From your experience can you tell me why the spoke breaks at the nipple almost all the time ? I would have thought the weakest part is closer to the hub .

[Iwan Kemp]

Go with Stans.

ZTR Olympic for XC racing

ZTR Arch for aggressive XC or heavier riders

ZTR Flow for Freeride or AM

 

They are seriously strong yet light. You won't have any issues with them. PM MTB Kid or contact Two Wheels Trading. They are the agents. They are also the WTB agents. Maybe you can take your rim issue up with them. My riding buddy had speeddiscs on his bike and he does lots of stuff on/with them you're not really supposed to and he hasn't had any issues.

 

www.notubes.com for more info on Stan's rims

[fandacious]

i've had spokes break in the middle. granted, it was a crap set of wheels. they came with the raleigh rc1000 i bought a few years ago. Must have been when i put the power down

[dirtrider]

i've had spokes break in the middle. granted' date=' it was a crap set of wheels. they came with the raleigh rc1000 i bought a few years ago. Must have been when i put the power down [/quote']

 

 

 

Mmmmm so then it should be possible to say what the problem is with a wheel by looking at where the spokes breaks ? And maybe you should lay off the power stuff a bit !

[Johan Bornman]

Johan I can not read anything when your text is so small !!! From your experience can you tell me why the spoke breaks at the nipple almost all the time ? I would have thought the weakest part is closer to the hub .

 

I agree with the small text issue. I just don't know how to fix it. You'll often see (as in this case) that those posts are edited. I go back to them and increase the text size but it just defaults back to 6-point.

 

The spokes break there because the wheelbuilder chose the wrong number of spoke crossings, causing the spoke to arrive at the rim at the wrong angle.

 

I've written extensively about that problem, even posted photos. If you search the phrase in blue on The Hub you'll come across it. Sorry to not write it out in full, I think it is things like this that should go into that FAQ that I'm working on.

 

If spokes break at the hub, they usually break because the wheel wasn't stress relieved. It is metal fatigue that breaks them there whereas stress cracks that break them at the other end.

 

A good wheelbuilder can control both maladies.

[fandacious]

i've had spokes break in the middle. granted' date=' it was a crap set of wheels. they came with the raleigh rc1000 i bought a few years ago. Must have been when i put the power down [/quote']

Mmmmm so then it should be possible to say what the problem is with a wheel by looking at where the spokes breaks ? And maybe you should lay off the power stuff a bit !

 

i cant help it. when i put the power down i break into wheelie and wheelspin all at once... its insane

[dirtrider]

Ok I will go and search ur article .

[Johan Bornman]

i've had spokes break in the middle. granted' date=' it was a crap set of wheels. they came with the raleigh rc1000 i bought a few years ago. Must have been when i put the power down [/quote']

 

That is extremely unusual but does happen under certain conditions:

 

1) Blunt trauma - a stick or pump gets into the wheel.

2) A score/scratch on the spoke's shaft develops into a crack.

 

Just by examining the spoke one can tell which of the two modes broke the spoke.

[fandacious]

i've had spokes break in the middle. granted' date=' it was a crap set of wheels. they came with the raleigh rc1000 i bought a few years ago. Must have been when i put the power down [/quote']

 

That is extremely unusual but does happen under certain conditions:

 

1) Blunt trauma - a stick or pump gets into the wheel.

2) A score/scratch on the spoke's shaft develops into a crack.

 

Just by examining the spoke one can tell which of the two modes broke the spoke.

 

It happened more than once.  I had the offending spoke replaced each time. after it happened the 3rd time I bought new wheels.

[Johan Bornman]

It happened more than once.  I had the offending spoke replaced each time. after it happened the 3rd time I bought new wheels.

 

I don't suppose you still have one of those spokes? I'd like to examine it and see what happened.

 

All I can think of is that the original wheelbuilder attempted to hold the spokes with a pair of pliers to prevent them from twisting as he tensioned it. The spokes move inside the plier jaws and score. The crack starts here.

 

I'll post some pictures of the various types of spoke breaks.

 

 

[fandacious]

naaah... dont have the wheels anymore. dont know what i did with them

[splat]

Go with Stans.

They are seriously strong yet light.

 

I would suggest Mavic XM819 (Disc or V-brake option)

They are strong and you won't have to do a tubeless conversion on them...

What makes them so strong?

 

JB is gonna question a statement like that...

splat2008-10-07 00:29:01

[Johan Bornman]

OK, some photos as promised.

This is a photo of a spoke that broke in trauma. A pump or toe interfered with the wheel and the spoke broke in pure tension. The telltale signs is the narrowing of the end and the characteristic cup-and-cone break.

 

 

 

This photo is of a fatigue break. Note the clean break but directional waves in the metal crystals showing us where the crack started and where it exited the spoke.  This is just beyond the spoke's elbow, indicating to us that the elbow was too long for the thickness of the hub flange and, the wheel wasn't stress relieved.

 

The crack started on the outside of the bend and moved inwards. That last little sharp lip is the straw that broke the camel's back. That is the only part of the spoke that broke in tension, the rest all through fatigue. Metal fatigue is well known to most school boys who bend pieces of wire until they're hot enough to sear the skin of the smallest boy in class. If you bend the wire too much, it'll break. This is the most common mode of failure for spoke breakages.

 

 

 

This is a photo of a spoke where its arrival angle exceeds the swivel angle of the nipple in the rim. The spoke thus arches as it approaches the nipple with the worst part of the bend inside the blank part of the nipple where the first thread starts. The bend in the thread cuts it like a laser - neat, clean and quick. The bend is subtle, but if you lay a straight edge through the middle of the nipple you'll see the spoke's deviation. The difference between a bad and durable wheel is a subtle as this. Needless to say it goes over the heads of many mechanics and sad to say, many wheel factories.

 

 

 

 

This is an inelegant solution to the problem when you're facing with an extreme case, such as a large-flange Rohloff hub on a mountain bike rim. So far so good.

 

Johan Bornman2008-10-07 00:40:59

[TheLegend]

 

naaah... dont have the wheels anymore. dont know what i did with them

 

you probably sold them as lighweight racing wheels, only used 3 time, as new

 

[GTRacing]

I had the same problem with spokes breaking at the hub, Still have the weels.(lx hub with wtb speed disk rims)

Replaced them with shimano m565 lx.

Not one problem since.

I clock the scale at 110kg and love jumping of the od rock here and there.