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My gravel bike is less than 2 years old and somehow I've broken all 7 of the rear-wheel, right-side, even-numbered spokes (the ones that see high tension on braking). None have broken twice and no others have broken. I have an 11 speed cassette so the wheel is dished quite a bit even with a disc brake.

I just discovered that the original spokes are stainless steel and my replacements are normal/plated/carbon steel. The gauge and length do match. Normal steel is slightly stronger than stainless.

It appears that I may have fixed the wheel accidentally by using normal steel replacement spokes but I'm wondering if this indicates a problem with the design of the wheel.

Does mixing spoke types have any negative consequenses?

(UPDATE May 8: I guess I should clarify some things. The wheel is nicely trued with fairly even spoke tension on all 28 straight spokes. I weigh about 185 lbs. It's been 5-6 months since the last spoke broke and I consider the wheel fixed and don't expect any more breakage. I follow Sheldon Brown's advice for stress relieving and truing. The replacement spokes are Bavel brand and were the cheapest on Amazon. The bike is the State Bicycle Company, 4130 All-Road with drop bars.

I know I broke two spokes on one ride but other than that they've broken and been replaced one at a time. I made an effort to replace and re-tension the broken spokes without altering any others to keep the wheel trued as it came from the factory but after the last break or two I did re-true the whole wheel. It's definitely rideable with one broken spoke so I just carry a zip tie to secure the flapping spoke and then fix it at home.

Someone suggested that these broken spokes are due to a manufacturing problem, not a design problem. That does seem more likely to me.)

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    I found this on the internet: "Carbon steel bars typically display lower fatigue resistance than stainless steel, especially in corrosive environments more susceptible to crack initiation and propagation". In general, I don't think the limiting factor is ultimate tensile strength when it comes to spokes breaking.
    – MaplePanda
    Commented May 10 at 15:03
  • You may be right but the higher tensile strength of carbon steel compared to some types of stainless steel is the only explanation I found for why all 7 of the stainless steel spokes that see highest tension on braking have broken and not a single one of the carbon steel replacements has.
    – user66598
    Commented May 11 at 14:17
  • Where exactly did the spokes break? Base of the threads, at the J-bend, right in the middle, ...?
    – MaplePanda
    Commented May 13 at 6:30
  • They all broke at the bend.
    – user66598
    Commented May 14 at 12:20
  • Ah, so yeah a manufacturing problem seems likely. The bend is a stress concentration and so if either the metal wasn't heat treated properly or there was a mistake while making the bend, the spokes could easily fail there over the long term.
    – MaplePanda
    Commented May 15 at 4:12

5 Answers 5

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I would rephrase some of what juhist wrote.

If I broke more than one spoke on a wheel while riding (i.e. you didn't break them in some sort of accident), I would consider having the wheel re-laced completely, as this could indicate a poor build. For example, the spoke tension may have been uneven, perhaps exacerbated if the rim was not flat, or not properly stress relieving, or some other thing. OEM wheels tend to be built by machine (albeit with human assistance), and they are not always well built. There is probably some systematic problem with this particular wheel, and it would be better for you not to break yet another spoke in the middle of a ride. I would just match the original spoke type, unless it were straight gauge. If it were, then most people would suggest going to a butted spoke, most likely a 14/15/14 gauge spoke (2.0 butted to 1.8mm).

juhist has a thing about 32 spoke wheels.1 He is a heavier rider. For the rest of us, it depends on the rim, the quality of the build, the total load, and what we're doing to the bike. The triple butted spokes he referenced are extra thick around the hub flange. They're good in MTBs and e-bikes. They are likely not necessary for most drop bar bike riders provided the wheel was built well and the rim is adequate for the loads it sees.

The hub flange gets indented regardless of spoke type. A wheelbuilder would know to re-lace it as originally built. There are more than one credible brand of spoke manufacturers. As far as I know, DT and Sapim are widely available in bike stores. As far as I know, Pillar is regarded as credible, but I think it's more of an OEM brand (supplied to people building stock wheels). It is possible to buy them, but I'd just get your store to help you and they'll probably have DT or Sapim.

If you are a heavier rider, then yes, the design could be at fault - particularly the rim type and spoke count.

Footnotes 1: In the 2000s and earlier, light aluminum rims typical on road bikes wouldn't be strong enough. MTB wheels would have had stouter rims that also were smaller. Manufacturing expertise and possibly materials quality have improved since then, plus rims have got heavier.

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    "If I broke more than one spoke on a wheel, I would consider having the wheel re-laced completely" - for otherwise unexplained breaks this is certainly true. One bike I used to look after broke one, then another, then several in quick succession. After a professional rebuild all was well. A spoke-for-spoke repair, replacing multiple broken spokes, can be appropriate if they've broken because of an external cause, like when my rear mech disappeared into the back wheel and the chain chewed up the outer drive-side spokes
    – Chris H
    Commented May 8 at 9:02
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    @ChrisH This is absolutely true. Will clarify.
    – Weiwen Ng
    Commented May 8 at 15:19
  • I don't remember for sure but I would guess that at least 5 of the 7 spokes that broke did so during braking. It makes sense since that's when the even numbered right side spokes see the most tension.
    – user66598
    Commented May 8 at 18:14
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They might indicate a manufacturing flaw rather than a design flaw. Some factory-built wheels aren't very good. Hopefully you've caught yours in time and the failure mode was such that a total rebuild wasn't necessary.

Personally, I always use stainless spokes (usually Sapim Race). I've had more issues with rusted spokes than broken ones. In fact, I've never broken a spoke on a wheel I've built, but I haven't broken many without an obvious cause overall.

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  • BTW, as I've said elsewhere recently, I'm fairly heavy, with fairly heavy bikes and often carrying a load. 32 spokes is normally adequate for me, though I prefer 36 especially at the back in most cases. I also get effectively heavier at the end of the day, as when tired in the dark, I'm not always quick enough to get off the saddle for rough bit of road.
    – Chris H
    Commented May 8 at 9:05
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    But even when wheels are clearly not very well laced - on my cheap road bike that also sees light gravel some of the spokes repeatedly become completely loose and make ugly sound - it does not have to result in nroken spokes. So far I have always just managed to re-tighten them and carry on. Commented May 8 at 10:26
  • @VladimirFГероямслава indeed - a few loose spokes can generally be fixed if caught in time. If uneven tension leads to excessive flexing or excessive load on a few, it's another matter. And the last broken spokes I encountered were from trying to tighten some that were loose but seized (Mavic seem to use steel nipples and non-stainless spokes, both of which are prone to rust)
    – Chris H
    Commented May 8 at 10:39
  • Good point about the problem possibly being in manufacture, not design. I'm the opposite of you, I've never seen a spoke break due to rust, so I'm glad I got plated spokes by accident. It does seem like some spokes have loosened up on their own so I plan to watch and see if that continues. I'm hoping it was just due to improper stress relieving at the factory.
    – user66598
    Commented May 8 at 18:10
  • @user66598 rather than it breaking on the road, I snapped the spoke at the top of the thread when I tried to tighten it, where it was rusted solid into the nipple (that was after 24 hours with penetrating oil).
    – Chris H
    Commented May 8 at 19:37
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Stainless steel spokes are the preferred type of spoke, and work extremely well in wheels that withstand huge loads. I wouldn't claim that those wanting greater strength should use carbon steel. Maybe in bolts carbon steel could be stronger as long as it doesn't corrode (example: 12.9 bolts), but the high quality of stainless steel used in spokes and the work hardening when drawing and butting makes the situation in spokes maybe not comparable to bolts. The highest quality stainless steels used by name brand manufacturers have been work hardened by drawing them into a wire and then work hardened even more by butting the spokes with a hammer, so the ultimate tensile strength and yield strength of those high-quality spokes will be huge, and in typical builds, they should be able to resist fatigue failure as well (but they do that better if you stress relieve the wheel).

Besides, in typical wheels, the limit of the load the wheel can withstand is caused by nipples self-loosening due to momentarily slack spokes. If the spokes are breaking but not self-loosening, it is most likely a combination of two factors, (1) you used no-name spokes as opposed to name brand (DT Swiss) spokes, (2) the spokes have not been stress relieved, as described in "The Bicycle Wheel" by Jobst Brandt. By using the best spokes you can find (DT Swiss triple butted stainless), you may be able to omit stress relieving. Jobst Brandt has said that the importance of stress relieving for durable wheels was discovered by using low quality spokes, and as materials improved, it became possible to build adequately durable wheels without stress relieving (but you should still stress relieve since it provides a margin of safety). Note that Jobst Brandt used 1.6mm midsection butted spokes and when stress relieved they didn't break in his wheels. If you use thicker butted spokes, the likelihood of spokes breaking is even lower.

You didn't mention using butted spokes in your question. This may also add to the likelihood of breaking spokes in addition to (1) and (2).

I would throw all your spokes away, replace them with DT Swiss Alpine III triple butted stainless steel 2.34mm/1.8mm/2.0mm spokes or maybe double butted 2.0mm/1.8mm/2.0mm spokes and build the wheel to a high and even spoke tension and then stress relieve.

My gravel bike is less than 2 years old and somehow I've broken all 7 of the rear-wheel, right-side, even-numbered spokes (the ones that see high tension on braking)

7*4 = 28. That is not an adequate number of spokes. The wheel may be able to be salvaged if you only use it for low loads. If you are overweight or carry lots of cargo on your bike, then I recommend replacing it with a 36-spoke wheel.

It appears that I may have fixed the wheel accidentally by using normal steel replacement spokes but I'm wondering if this indicates a problem with the design of the wheel.

Could have been a bad batch of spokes, or spokes from a no-name manufacturer, or lack of stress relieving or most likely a combination of all of these factors. 28 spokes is a problem in the design of the wheel, but still, a wheel that has so many spoke failures should be rebuilt entirely, with all spokes being replaced. Nipples can be reused if their threads are not damaged, rim can be reused, hub maybe can be reused but please make sure to lace it the same way if the hub flanges have been indented by high spoke tension. Actually, it might make sense to replace all spokes one by one, not all at once, to ensure it's laced the same way so the hub flange indentations will match the new spoking.

Since 28 spokes is marginal, triple butted stainless steel spokes from a name brand manufacturer are recommended, although your hub flanges may have been indented by non triple butted spokes so using normal butted spokes (example: by replacing 2.0mm/2.0mm/2.0mm spokes with 2.0mm/1.8mm/2.0mm spokes) might have benefits in this very special case of respoking an old hub. For new builds, always prefer triple butted.

Then, when all spokes have been replaced, remember to true and tension the wheel to a high and even spoke tension and then stress relieve the wheel.

Does mixing spoke types have any negative consequenses?

Not any major issues, but by mixing poor and good spokes the weakest spoke is the weakest link of the chain. Besides, if the old spokes have failed so much, all of them should ideally be replaced.

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  • I haven't heard of any huge row of repeatedly breaking spokes on, e.g., Mavic Allroad, which are 28-spoke gravel wheels. Well built 28-spoke wheels are just fine. Commented May 8 at 10:23
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    Sapim are another good source of double-butted spokes. I use Sapim race for pretty much all of my builds with no issues
    – Chris H
    Commented May 8 at 10:51
  • But the wheel is fine; it's nice and true and no spokes have broken for months. I don't plan to do anything to it unless another spoke breaks.
    – user66598
    Commented May 8 at 17:51
  • I was debating trying to figure out what's wrong with the wheel and do a rebuild or something to stop the spokes from breaking in the future but once I realized that only even right-side spokes were breaking it seemed like I should leave the others alone.
    – user66598
    Commented May 8 at 18:06
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Not necessarily per spoke mix... while almost all 11s have wide left side dish, uniform spoke tension per side should off set a spoke mix.

I question your assertion stainless vs "normal" steel... latter being superior which more a function of spoke Q rather than stated metallurgy... which who knows per quality. Sapim stainless are some of the best made... there're cheaper imitators which are just that.

MAIN ISSUE: most likely, note your rt breaking spokes are INBOUND... meaning likely w the original spoke the elbows make no flange contact... are unsupported. 'hanging in the wind' I call that. LEFT side braking spokes being trailing OUTBOUND most often are supported by the flange making less elbow strain.

Your steel replacements rt inbound likely produce some flange support.. hence more durable.

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    Depending upon what grade of stainless steel you're talking about, carbon steel has a higher tensile strength. That's just a fact. Many other factors affect quality like you say, but at the end of the day, I haven't broken a single replacement spoke, and they were installed in exactly the same way. No doubt, OEM spokes on a cheap bike can be terrible, but on a $900 bike I would have expected them to be better than the cheapest replacement spokes I could find on amazon (that was before I switched to Temu).
    – user66598
    Commented May 8 at 17:50
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"I would throw all your spokes away, replace them with DT Swiss Alpine III triple butted stainless steel 2.34mm/1.8mm/2.0mm spokes or maybe double butted 2.0mm/1.8mm/2.0mm spokes and build the wheel to a high and even spoke tension and then stress relieve"

  1. stress relieve AS you build... grabbing spokes AND lateral force on hub ea side on floor.
  2. I call it the 'sergeant spoke' ... one carry highest tension usually breaks. Machine made wheels good for this w lower Q spokes and poor elbow flange fit.
  3. get DS rear very uniform KGF and then dish LS lubing spoke rim interface.
  4. I calculate NDS slightly long... just enough to add a drop of finger nail polish to lock the spoke
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  • stress relieve AS you build... grabbing spokes AND lateral force on hub ea side on floor. That's not going to hurt (the wheel anyway - your hands and fingers might not be so happy with all the squeezing of spokes...), but if the spokes aren't close to final tension the force at the J-bend won't be maximized and might not be high enough to relieve the stresses created by the manufacturing process. Commented May 8 at 12:19
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    Those are good tips but I'm not rebuilding the wheel. Also, it is true that squeezing spokes like that can cause nerve damage long-term so I use Sheldon Brown's method of over tightening slightly and then loosening. A good tensionometer is too expensive IMO but a cheap uncalibrated one is very useful to gauge how uniform the tension is when I'm dealing with a really bad wheel.
    – user66598
    Commented May 8 at 18:02
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    For tension uniformity, plucking the spokes and observing the tone by your ear works just fine. Tensiometers are mainly useful for checking what the amount of tension is in Newtons once they have been equalized by ear. Besides, the nerve damage can be avoided if you wear thick work gloves, but for low numbers of built wheels, let's say one pair every 5-10 years, it's safe to stress relieve without gloves.
    – juhist
    Commented May 9 at 16:02
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    Also, I don't recommend overtightening and backing up except of course as a method to avoid spoke wind-up. The reason is that the final tension in Newtons is so close to what the nipple threads can take that for adequate stress relieving, there's a risk of damaging nipple threads if you do it by overtightening. If you do it by grasping and squeezing, the nipple threads are stationary so it probably has smaller chance of damaging them (well unless the spokes are way too short in which case they can be damaged).
    – juhist
    Commented May 9 at 16:04

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