Another broken spoke...

[User6179]

It doesn't solve the problem. The second weakest spot on a spoke is where the thread starts. Straight pulls break there instead, and equally quickly. Rims fatigue just like any other metal but it does give you ample warning that it is about to start. If your spokes are good, you can at least replace the rim without replacing all the spokes.
Straight pull spokes have other problems too, not least is availability. If you break one of those, you pay big for replacements since it is usually a wheel part with part number etc. that has to be ordered for that wheel.

The best bet remains a J-bend but it has to be stress-relieved.

IME straight pull bladed spokes only snap at the nipple with corrosion not fatigue , in about 20000 miles cycled I have not snapped a single rear straight pull spoke and only snapped some front wheel spokes due to salt corrosion , I have cracked 3 rear rims though.

In about my last 5 - 6000 miles cycled on j-bend spoked wheels I have snapped 7 or 8 spokes and changed some more before they snapped .

if I could build my perfect wheel it would be straight pull but with 32 spokes .

 

[Spoked Wheels]

New wheels is the best bet. I had a tricross a few years back & had 3 spokes go (all at different times) & kind of lost confidence in the bike, or certainly the wheel & I don't fancy being miles from home with a broken spoke. I haven't been under 100kg for many years now , so my weight is probably an issue, but having handbuilt wheels on 2 of my bikes I've not had any problems with them (touch wood)

Excellent but do you ride them enough? .... you have too many bikes now I think

I don't understand why putting your luggage in a rucksack rather than on the bike would make a difference?

Having a 5kg pannier is like the rider carrying an extra 10kg in weight. Hence the need for touring wheels being particularly strong.

Spokes all fatigue at the same rate, thus if one or two spokes break, the others are also fatigue and will break sooner or later as well.

A good wheelbuilder can build a wheel and stress relieve the spokes so that metal fatigue takes a very, very long time to set in, effectively until the wheel's useful life is over.

Thus, find a wheelbuilder that understands how stress relieving works. Attempting to do this procedure on your existing wheel is futile, it has to be done when the spokes are new or not already fatigued. Factory wheels are often not stress relieved, but that doesn't mean every wheelbuilder understands the process either.

Yes, spokes break because of metal fatigue, the most common places are on the spoke bend and the threaded part.

Having one spoke loose means the neighbouring spokes have to share the load hence they will fatigue too. There might be other spokes in a different section of the wheel that are loose too and they will suffer the same fate. As you correctly stated, this constant compress and stress every time the wheel goes round has the same effect as the "bending a wire coat hanger until it breaks" you also said.

Stress relieving is an important part of wheelbuilding. I have always done it because that is how I learnt wheelbuilding, however, I now I understand what it actually does in details. As long as the stress relieving is done properly there's not need to understand the physics of it.

Stress relieving is not the only important step in building a good, reliable and long lasting wheel though. I use two stress relieving methods just to make sure

 

[Crankarm]

Hand built wheels for all my bikes by good wheel builders. Never had a broken spoke yet (except years ago with factory wheels) despite carrying some serious weight in my panniers. Commuting bike has 36 spoke wheels, road bikes 24 and 32 spokes. I did have a very badly built hand built wheel at the start of the year from Grafham Cycles which I had to have rebuilt by a competent wheel builder Andy at Bicycle Ambulance in Cambridge. So far so good it is strong and remains true, no spokes coming undone and the spokes are the correct length. The best ever wheel builds I had though was from Monty at Condor Cycles. Fabulous wheels - straight and strong as the day he built them and nice ride.

So to the OP buy a set of hand built wheels on good hubs.

 

[Yellow Saddle]

Having one spoke loose means the neighbouring spokes have to share the load hence they will fatigue too. There might be other spokes in a different section of the wheel that are loose too and they will suffer the same fate. As you correctly stated, this constant compress and stress every time the wheel goes round has the same effect as the "bending a wire coat hanger until it breaks" you also said cut cut cut cut.....

The two spokes adjacent to a loose or missing spoke don't experience much additional stress. In a good wheel with all its spokes present, all spokes fatigue at the same rate. The only reason they don't all break at the exact same moment is because of manufacturing and metallurgical irregularities and luck.
In a wheel where one spoke is missing, the adjacent spokes undergo the same number of stress cycles as the other spokes (once per wheel revolution), but the cycle is somewhat deeper and longer. The additional length of the cycle is not a factor, but the additional amplitude of the cycle does have an effect that we can calculate. It would be the same as for a similar wheel with similar spokes, but with half the number of spokes in the wheel. For instance, if it is a 36 spoke wheel with one broken spoke, the spokes adjacent to the missing one would experience a stress amplitude like that of a 18-spoke wheel. Although this is larger, it is nothing near large enough to make any perceptible difference in their life, given that the rider will have it repaired sooner rather than later, simply because of the inconvenience thereof.

 

[User6179]

The two spokes adjacent to a loose or missing spoke don't experience much additional stress. In a good wheel with all its spokes present, all spokes fatigue at the same rate. The only reason they don't all break at the exact same moment is because of manufacturing and metallurgical irregularities and luck.
In a wheel where one spoke is missing, the adjacent spokes undergo the same number of stress cycles as the other spokes (once per wheel revolution), but the cycle is somewhat deeper and longer. The additional length of the cycle is not a factor, but the additional amplitude of the cycle does have an effect that we can calculate. It would be the same as for a similar wheel with similar spokes, but with half the number of spokes in the wheel. For instance, if it is a 36 spoke wheel with one broken spoke, the spokes adjacent to the missing one would experience a stress amplitude like that of a 18-spoke wheel. Although this is larger, it is nothing near large enough to make any perceptible difference in their life, given that the rider will have it repaired sooner rather than later, simply because of the inconvenience thereof.

I have found on j-bends spoked wheels Non drive side tend to fatigue a lot quicker than the drive side , I don't know if this true for everyone but certainly my experience.

 

[Yellow Saddle]

IME straight pull bladed spokes only snap at the nipple with corrosion not fatigue , in about 20000 miles cycled I have not snapped a single rear straight pull spoke and only snapped some front wheel spokes due to salt corrosion , I have cracked 3 rear rims though.

In about my last 5 - 6000 miles cycled on j-bend spoked wheels I have snapped 7 or 8 spokes and changed some more before they snapped .

if I could build my perfect wheel it would be straight pull but with 32 spokes .

Not having any experience with salted roads, I've never seen a spoke that broke because of salt corrosion. I have seen plenty of corroded aluminium nipples break though. Your experience of J-bend spokes is unfortunate and I suspect you had poorly built wheels. They are far more durable than that.

 

[Yellow Saddle]

I have found on j-bends spoked wheels Non drive side tend to fatigue a lot quicker than the drive side , I don't know if this true for everyone but certainly my experience.

Statistically it is the other way round. However, outbound J-bends on the left side require extra care because they have to be manually bent into an acute angle to follow the exit line of the hub. If that's not done, they have plenty of residual stress and would behave like your sample.

 

[confusedcyclist]

Where did you accumulate this knowledge @Yellow Saddle ?

 

[Spoked Wheels]

The two spokes adjacent to a loose or missing spoke don't experience much additional stress.

Do you have any evidence of this? I might have come to the wrong conclusion when reading several authors... Jobs Brandt says "Spoke fatigue is caused by the combination of static load, the carried load, the
distance traveled, and the number of spokes that share the work. The heavier the
load, the more rapidly spokes fatigue" AND "Spoke fatigue is caused almost exclusively by the radial load from the weight of the bicycle and rider." That is how I visualise it, A missing spoke would contribute to the strength of the wheel but that is not what we are talking about here. I'd really like to read some evidence of what you just said cause it's interesting. Not that is really matters where the next spoke is going to brake, I use a huge magnifying glass to inspect the rest of the spokes of wheels that have had a broken spoke. The important part is what to do to prevent this from happening or extend the life of the spoke.

 

[Spoked Wheels]

I have found on j-bends spoked wheels Non drive side tend to fatigue a lot quicker than the drive side , I don't know if this true for everyone but certainly my experience.

No Eddy, the DS spokes are the spokes that suffer most of the punishment and since I have Jobs Brandst book opened I'll quote what he says and it's actually what I've seen too.

"
Rear wheel spokes fail more often because rear wheels carry more weight,
receive more stress from the rigidity of the rear frame triangle, and most of all,
carry most of their load on the spokes of the right side. To make room for
multisprocket gear clusters, rear wheels are asymmetric. This asymmetry makes
spokes on the right side at least twice as tight as the ones on the left. The load
carried by each side of the wheel is in direct proportion to the spoke tension, so
a 36-spoke rear wheel with a seven-speed gear cluster is, in effect, hardly more
than an 18-spoke wheel. The greater the "dish" or asymmetry, the weaker the
wheel and the sooner the spokes will break from fatigue"

 

[Yellow Saddle]

Do you have any evidence of this? I might have come to the wrong conclusion when reading several authors... Jobs Brandt says "Spoke fatigue is caused by the combination of static load, the carried load, the
distance traveled, and the number of spokes that share the work. The heavier the
load, the more rapidly spokes fatigue" AND "Spoke fatigue is caused almost exclusively by the radial load from the weight of the bicycle and rider." That is how I visualise it, A missing spoke would contribute to the strength of the wheel but that is now what we are talking about here. I'd really like to read some evidence of what you just said cause it's interesting. Not that is really matters where the next spoke is going to brake, I use a huge magnifying glass to inspect the rest of the spokes of wheels that have had a broken spoke. The important part is what to do to prevent this from happening or extend the life of the spoke.

I'm not sure which party of my post you're questioning. BTW, nothing that I've said is contradicting to your Jobst quote. I've merely given a quantative view of the additional stress experienced by two spokes adjacent to a missing one.
Perhaps if you are more specific, I can answer.

Edit: Actually I see it now, I didn't read properly. I said it doesn't receive much additional stress. "Much" is of course not a quantative statement and I proceeded to explain how much. This statement is in response to another one that implied that the two adjacent spokes (to the missing one) are in imminent danger (my emphasis). I say no, they are not in imminent danger because the additional stress is merely XYZ, as I explained.
Do I have evidence? Yes. The number of spokes involved in supporting the payload are those in the load affected zone of the wheel. This zone is a small arc with one or more spokes within it. The size of the arc is defined by the rim's strength. The stronger the rim, the bigger the zone, the weaker the rim, the smaller the one. Likewise, for an otherwise identical wheel of say 32 spokes but one with a strong rim and one with a weak rim, the strong wheel's zone will involve say 8 spokes and the weak one half of that. This means that with a stronger rim we can safely use fewer spokes and not compromise durability. We can do that with a factor of 2, if we choose the wheel described above. In other words, an 18-spoke wheel with the strong rim will fatigue just as fast as a 32-spoke wheel with a rim that's 50% weaker.
Turning that around, you can see how I say that if you keep the rim the same but reduce the number of spokes, their fatigue is increased by the factor of reduction - in this case 2.

 

[Colin_P]

I'm no expert but what I have found quite simply is that although true, the spoke tension if not high enough on all the new wheels I've had, whether replacement wheels or on a new bike. I got fed up having to have the wheels trued so got into it myself.

All my stuff is mid to low end and what I do these days is completely relax the tension on all the spokes and then start again, equally tensioning each spoke reasonably tight and then start re-truing. As said I'm no expert but this seems to work for me. It takes ages and ages to do but I find it very theraputic and it really isn't that difficult. I'm sure with a tension gauge and more practice I'd get quicker and even more precise. A truing stand does help though and I was able to knock one up out of bits and bobs.

Oh, also a heavy chap here 110kg.

If you can, my advice is to have a go, get the spoke key out and get stuck in.

 

[Nigelnaturist]

Moves the weight forward, spreads the load more evenly between the 2 wheels. It also means the weight of the luggage is 'sprung' by my legs, and not rigidly.affixed above the rear wheel with no means of shock absorption.

Its 5kgs it will make sod all difference, I was forever braking spoke on my Weinmann wheels, with or without a rear bag, since then I have had a set of RS10's and 11's and broke one on the front of the RS10's after nearly a year, and one on the rear of the RS11's after hitting a stone pretty hard, though the spoke didn't go till a few weeks later, I carry pretty much the same in the bag sometimes up to 10kg's though usually much less more like the 5kg in total as mentioned., I am about 78-79kgs, but to be fair I ride with just the rack possibly 80-90% of the time, and the bike weighs about 12.5-13kgs with guards and rack, plus lights gps ect......

 

[Nigelnaturist]

IME straight pull bladed spokes only snap at the nipple with corrosion not fatigue , in about 20000 miles cycled I have not snapped a single rear straight pull spoke and only snapped some front wheel spokes due to salt corrosion , I have cracked 3 rear rims though.

In about my last 5 - 6000 miles cycled on j-bend spoked wheels I have snapped 7 or 8 spokes and changed some more before they snapped .

if I could build my perfect wheel it would be straight pull but with 32 spokes .

I think I would have to agree with you, but as I only have limited experience of wheels not sure how constructive it would be, as the RS10's the week after the front spoke went I found a crack in the rear rim.

 

[PpPete]

I'm no expert but what I have found quite simply is that although true, the spoke tension if not high enough on all the new wheels I've had, whether replacement wheels or on a new bike. I got fed up having to have the wheels trued so got into it myself.

All my stuff is mid to low end and what I do these days is completely relax the tension on all the spokes and then start again, equally tensioning each spoke reasonably tight and then start re-truing. As said I'm no expert but this seems to work for me. It takes ages and ages to do but I find it very theraputic and it really isn't that difficult. I'm sure with a tension gauge and more practice I'd get quicker and even more precise. A truing stand does help though and I was able to knock one up out of bits and bobs.

Oh, also a heavy chap here 110kg.

If you can, my advice is to have a go, get the spoke key out and get stuck in.

You could probably save yourself a good deal of time by not slacking them off completely but instead plucking the spokes (like a guitar string) and tightening only the ones that sound 'flat', compared with their neighbours on the same side of the wheel.
If you have a musical ear (i havn't) you can probably be nearly as good as a cheap tension gauge like a Park TM-1.

If you have a wheel that is laterally true but the current spoke tensions are wildly different (typically tight in two places opposite each other and slack at 90°) you may find that the rim has a natural slight pringle to it. That needs sorting before trying to lace the wheel.