Broken spoke - replace or respoke wheel ?

[Weight Weenie]

hey all

 

Did a search but no info

 

Saw today while topping up the stans in my wheels that the one spoke on my rear training mtb wheel is broke clean off.

Dont know what happened, heard something twang during a road mtb ride on thursday so this must have been it.

 

Wheels arent new as I bought them 2nd hand from my uncle and recently has the spokes re-tentioned as the were a bit loose.

They are 355 rims with DT spokes, sapim alu nipples and DT 240s hubs, laced 3 across.

 

Im really light and havent hooked anything or damaged the rim so I guess its just metal fatigue from time

Question is can I just have the broken one replaced or must the whole wheel be rebuilt as the others are likely to do the same, possibly during the race ?

Need to use this wheel for the 3 towers and leaving thursday so dont have much time or the budget to do a full rebuild unless really needed.

 

Advice/opinions ?

 

Thanks,

WW.

[wapad]

hey all

 

Did a search but no info

 

Saw today while topping up the stans in my wheels that the one spoke on my rear training mtb wheel is broke clean off.

Dont know what happened, heard something twang during a road mtb ride on thursday so this must have been it.

 

Wheels arent new as I bought them 2nd hand from my uncle and recently has the spokes re-tentioned as the were a bit loose.

They are 355 rims with DT spokes, sapim alu nipples and DT 240s hubs, laced 3 across.

 

Im really light and havent hooked anything or damaged the rim so I guess its just metal fatigue from time

Question is can I just have the broken one replaced or must the whole wheel be rebuilt as the others are likely to do the same, possibly during the race ?

Need to use this wheel for the 3 towers and leaving thursday so dont have much time or the budget to do a full rebuild unless really needed.

 

Advice/opinions ?

 

Thanks,

WW.

 

you should be able to replace the damaged spoke without affecting performance just get them to check that the wheel is still true, I had a spoke replaced not to long ago on the mavic 317 with dt hub also running tubeless

 

it cost me 20 -50 bucks including spoke and labour

[Weight Weenie]

Wiele ! Excuse the pun haha !

Thanks I'll take it to the lbs

[Johan Bornman]

Replace that one spoke. However, if you break another one soon, you have a trend. Then replace them all.

[Weight Weenie]

Replace that one spoke. However, if you break another one soon, you have a trend. Then replace them all.

 

Dankie het so gemaak.

Is there an approximate life time on spokes before one should rather replace them ?

Guess allot of factors come into play but ballpark ?

[Johan Bornman]

Spoke durability is 100% under the wheelbuilder's control. A Good wheelbuilder should be able to offer you a lifetime gaurantee on spoke breakages. The exception would be a wheel where design criteria are not flexible enough to accommodate what has to be done. Examples of this would be large flange hubs on deep section rims or, rims drilled for specific spoke configurations but not build with those configurations.

 

On a standard wheel the wheelbuilder should be able to build the wheels with infinitely durable spokes that will outlast the hubs and rims many times.

 

Spokes should thus not be replaced routinely. However, a poorly built wheel will require new spokes since once they are fatigued, they're history.

[dirtrider]

Ball park ? Like Johan said , if they start going one after the other replace them all . I have been racing/riding with a broken spoke on rear for 4 months now . But had to replace it for the weekends race .

[Weight Weenie]

Ok thanks will put on some new spokes after the 3 towers

[Reg Lizard]

broke a nipple on one of my wheels (spoke was still in tact) was told by Cycle Lab the whole wheel had to be respoked and would cost ±R1500. Insisted that they only replaced the one after having to get the manager involved and after 6-7months the wheels are still fine.

[Madala]

From the Sapim Web Site:-

 

 

A survey of frequent incidents recorded by our laboratory research team and race mechanics.

When do spokes or other wheel components break?

 

Spokes in a correctly built wheel only break as a result of normal metal fatigue after years of intensive use.

 

* At the end of its life, the material has lost its original cohesion and elasticity.

* If material is forced while lacing the hub, the spokes can be pulled over causing material weakness.

The original bend angle of 95° should remain intact.

* Most wheel or spoke breakages occur as a result of insufficient and/or irregular spoke tension.

* A spoke breaks when metal fatigue passes a critical point. Good assembly can increase the resistance to breakage.

The art of wheel building is to create an equal increase in the tension of all the spokes individually and at the same time to make sure that the rim stays round and true. When a wheel is built, bring the spokes to a final equal tension. A perfect wheel does not run out of true when it is used; instead it actually helps to prevent metal fatigue in spokes, rim and hub.

* Weight is a factor: 90 kg (200 lbs) on loosely tensioned wheels will always cause them to ovalise. Constant flex within the wheel will cause premature fatigue, especially in spokes.

In other words: the wheel should retain its original shape as much as possible.

 

 

 

Where and when does a spoke break?

 

Normally just before the bend (this is fairly standard after many years use)

 

* The rim has been damaged - even the smallest dent can be the cause;

* The use of non-compatible components;

Irregular tension on the spokes;

* A gap exists in the spoke-nipple alignment;

* Is it possible to replace 1 or 2 spokes or do you have to replace all the spokes and re-spoke the wheel? If you do not re-spoke the wheel, the replaced spokes will have to be very tightly tensioned if the wheel is to be round and true.

Do not forget when the first spoke breaks, all the other spokes suddenly have a different tension pattern! Also the rim structure goes out of line.

If you only replace 1 or 2 spokes, you can expect these or the spokes next to them to break again. It is best to re-spoke the entire wheel and to replace the hub just in case the hub holes are damaged. It is possible to re-use the hub by mounting the spokes in the opposite direction (i.e. not in the direction of the ovalisation of the hub holes).

 

The spoke head breaks off (this is unusual)

 

* Bad positioning of the head in the hub (e.g. a slant position puts all the pressure on one side of the bottom of the spoke head. As a result the head snaps off, the so-called "bottle cap effect").

* The hub flange is too thick and is not suited to the length of the spoke bend (i.e. all the pressure is on the head, which will be excessively stressed and rip off).

* If the wrong cross pattern is chosen, e.g. cross 4 on large flange hubs, the spoke bend can rub against the adjacent spoke head. This should be avoided.

 

The spoke thread breaks in the nipple

 

* This often occurs as a result of nipple/rim and spoke mis-alignment.

* If spokes are used which are too long, new threads in the nipple will be made. Under heavy pressure the spoke threads will be stressed too greatly.

* Spokes which are too short may also break at the spoke thread.

 

When the thinner middle section breaks (on single or double butted spokes)

 

* Any object striking a moving wheel causes damage (sometimes only visible with a magnifying glass or microscope).

* Top quality manufacture will safeguard against damage. Lower standard processes will produce an inferior quality. SAPIM draws wire in such way that no change in molecular material structure occurs. The spoke does not twist much when it is built into a wheel.

* Aerodynamic, elliptical spokes, such as the SAPIM CX-Ray spoke, are best fitted with a special CX-Ray key.

This will prevent the spokes from twisting during lacing and centring.

[Johan Bornman]

From the Sapim Web Site:-

 

 

A survey of frequent incidents recorded by our laboratory research team and race mechanics.

When do spokes or other wheel components break?

 

Spokes in a correctly built wheel only break as a result of normal metal fatigue after years of intensive use.

 

* At the end of its life, the material has lost its original cohesion and elasticity.

* If material is forced while lacing the hub, the spokes can be pulled over causing material weakness.

The original bend angle of 95° should remain intact.

* Most wheel or spoke breakages occur as a result of insufficient and/or irregular spoke tension.

* A spoke breaks when metal fatigue passes a critical point. Good assembly can increase the resistance to breakage.

The art of wheel building is to create an equal increase in the tension of all the spokes individually and at the same time to make sure that the rim stays round and true. When a wheel is built, bring the spokes to a final equal tension. A perfect wheel does not run out of true when it is used; instead it actually helps to prevent metal fatigue in spokes, rim and hub.

* Weight is a factor: 90 kg (200 lbs) on loosely tensioned wheels will always cause them to ovalise. Constant flex within the wheel will cause premature fatigue, especially in spokes.

In other words: the wheel should retain its original shape as much as possible.

 

 

 

Where and when does a spoke break?

 

Normally just before the bend (this is fairly standard after many years use)

 

* The rim has been damaged - even the smallest dent can be the cause;

* The use of non-compatible components;

Irregular tension on the spokes;

* A gap exists in the spoke-nipple alignment;

* Is it possible to replace 1 or 2 spokes or do you have to replace all the spokes and re-spoke the wheel? If you do not re-spoke the wheel, the replaced spokes will have to be very tightly tensioned if the wheel is to be round and true.

Do not forget when the first spoke breaks, all the other spokes suddenly have a different tension pattern! Also the rim structure goes out of line.

If you only replace 1 or 2 spokes, you can expect these or the spokes next to them to break again. It is best to re-spoke the entire wheel and to replace the hub just in case the hub holes are damaged. It is possible to re-use the hub by mounting the spokes in the opposite direction (i.e. not in the direction of the ovalisation of the hub holes).

 

The spoke head breaks off (this is unusual)

 

* Bad positioning of the head in the hub (e.g. a slant position puts all the pressure on one side of the bottom of the spoke head. As a result the head snaps off, the so-called "bottle cap effect").

* The hub flange is too thick and is not suited to the length of the spoke bend (i.e. all the pressure is on the head, which will be excessively stressed and rip off).

* If the wrong cross pattern is chosen, e.g. cross 4 on large flange hubs, the spoke bend can rub against the adjacent spoke head. This should be avoided.

 

The spoke thread breaks in the nipple

 

* This often occurs as a result of nipple/rim and spoke mis-alignment.

* If spokes are used which are too long, new threads in the nipple will be made. Under heavy pressure the spoke threads will be stressed too greatly.

* Spokes which are too short may also break at the spoke thread.

 

When the thinner middle section breaks (on single or double butted spokes)

 

* Any object striking a moving wheel causes damage (sometimes only visible with a magnifying glass or microscope).

* Top quality manufacture will safeguard against damage. Lower standard processes will produce an inferior quality. SAPIM draws wire in such way that no change in molecular material structure occurs. The spoke does not twist much when it is built into a wheel.

* Aerodynamic, elliptical spokes, such as the SAPIM CX-Ray spoke, are best fitted with a special CX-Ray key.

This will prevent the spokes from twisting during lacing and centring.

 

 

There are so many errors in this piece of fiction that I want to cry.

[Bat-ass]

My Easton EA 70's have broken 2 spokes recently (wheels only 3 months old). The first one LBS just replaced the spoke, 2 weeks later next one broke, now i have sent them to the agents to be rebuilt.

Arnt Eastons supposed to be hand build by only the best??