Broke 4 spokes on drive side rear tire….
#1
Interested Backpacker
Thread Starter
Broke 4 spokes on drive side rear tire….
…each one in the center of spoke. Why is this happening?
The bike is a Sun EZ Sport AX and most of my weight is over the rear tire. Wheel has 36 spokes. Granted, I am 220 lbs, but figured that would not cause spoke to break in center, but rather at the nipple with flex. I am running tires at 90 psi. 26 x 1.75” tire.
Help.
The bike is a Sun EZ Sport AX and most of my weight is over the rear tire. Wheel has 36 spokes. Granted, I am 220 lbs, but figured that would not cause spoke to break in center, but rather at the nipple with flex. I am running tires at 90 psi. 26 x 1.75” tire.
Help.
#2
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Did anything knock the rear derailleur into the spokes? It sounds like something must have hit and scratched the spokes for them to break in that location.
#3
Interested Backpacker
Thread Starter
All four spokes have broken individually over time in the last year. All four have been on the drive side. This was a used bike purchase for me and I really do not know age of bike.
I love the way this bike rides compared to my DF bikes. If I can get this recumbent dependable, like to try a couple of Rando rides. Is it possible that all spokes are approaching fatigued state and need to be replaced? Do LWB rear tires stress more easily than a short wheel base?
I love the way this bike rides compared to my DF bikes. If I can get this recumbent dependable, like to try a couple of Rando rides. Is it possible that all spokes are approaching fatigued state and need to be replaced? Do LWB rear tires stress more easily than a short wheel base?
#4
Senior Member
It is more common for spokes to fail in the center, though generally failures are more common on the nondrive side. When they have enough radial load the spokes will detension and flex in the center. If you have that many spoke failures it's likely that the rest are all fatigued. A recumbent can be harder on spokes because it's harder to unweight the bike like you can on an upright bike and tends to have even more of a rear weight bias. Still, a 36 spoke wheel on a 26" rim should be more than plenty strong for your application. Get a good wheelbuilder to rebuild your wheel with double butted spokes.
#5
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#6
Senior Member
If your spokes are not correctly tensioned, they can fatigue more quickly. Straight gauge spokes? I had the same issue on a factory rear wheel. I built a new wheel with butted spokes, have not broken any spokes since. A wheel can look true but have poor tensioning.
#8
Interested Backpacker
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#9
Interested Backpacker
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It is more common for spokes to fail in the center, though generally failures are more common on the nondrive side. When they have enough radial load the spokes will detension and flex in the center. If you have that many spoke failures it's likely that the rest are all fatigued. A recumbent can be harder on spokes because it's harder to unweight the bike like you can on an upright bike and tends to have even more of a rear weight bias. Still, a 36 spoke wheel on a 26" rim should be more than plenty strong for your application. Get a good wheelbuilder to rebuild your wheel with double butted spokes.
I think this may have contributed to the last two breaks. I ran the pressure up from my normal 80 psi to 90 psi, thinking this would help...., but it was actually counter productive. From what I have read, thinking that 36 spokes is a good number and that is what is on my touring bike (Trek 520). I am thinking I just need new spokes as the ones on the rim may just have gotten old and fatigued. Thanks for all your help.
#10
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Having four spokes break suggests this will continue to be a problem. At 220#, you may better be served by a hand built and tensioned wheel. If the rim and hub are in decent condition, those may be re-used to save some $$$.
#11
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I've broken a number of spokes over the years. Probably 80% were at the head, with the remaining 20% just above the nipple. (Then I bought a tensiometer, and later started to run out of broken spokes for various "tools".)
Then a couple years ago a misaligned or misadjusted derailer went into a wheel. A few weeks later, I started breaking spokes in the middle where the chain had scratched them. All head-in, so the spokes were on the outside of the rim.
If you want to keep your wheel, try the Brandt stress relief method. First make sure the wheel is trued and tensioned. Then put on some heavy leather work gloves, grab each pair of near-parallel spokes, and squeeze the tar out of them. You want to squeeze hard enough that any flawed spoke breaks right then. Get back out on the road and ride some more.
If you buy a new wheel, make sure the person who last touches it knows what they're doing. Many people don't.
Then a couple years ago a misaligned or misadjusted derailer went into a wheel. A few weeks later, I started breaking spokes in the middle where the chain had scratched them. All head-in, so the spokes were on the outside of the rim.
If you want to keep your wheel, try the Brandt stress relief method. First make sure the wheel is trued and tensioned. Then put on some heavy leather work gloves, grab each pair of near-parallel spokes, and squeeze the tar out of them. You want to squeeze hard enough that any flawed spoke breaks right then. Get back out on the road and ride some more.
If you buy a new wheel, make sure the person who last touches it knows what they're doing. Many people don't.
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#12
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I think your advice is sound. Time to get the wheel reworked and put the correct tension on the spokes and upgrade all spokes to a sturdier material. When I went to look up what a double butted spoke was, I found the following comment on www.wheelbuilder.com ; Tire pressure: Increased tire pressure has the effect of causing lower spoke tension, which increases fatigue sensitivity.
I think this may have contributed to the last two breaks. I ran the pressure up from my normal 80 psi to 90 psi, thinking this would help...., but it was actually counter productive. From what I have read, thinking that 36 spokes is a good number and that is what is on my touring bike (Trek 520). I am thinking I just need new spokes as the ones on the rim may just have gotten old and fatigued. Thanks for all your help.
I think this may have contributed to the last two breaks. I ran the pressure up from my normal 80 psi to 90 psi, thinking this would help...., but it was actually counter productive. From what I have read, thinking that 36 spokes is a good number and that is what is on my touring bike (Trek 520). I am thinking I just need new spokes as the ones on the rim may just have gotten old and fatigued. Thanks for all your help.
#13
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Additionally, when spokes detension and retension during rotation, the part that flexes isn’t mid-shaft. It flexes at the elbow as most spokes have a sloppy fit in the hub. As the rim deforms upward, the tension on the spoke is released and the elbow moves upward. As tension is placed back on the spoke the elbow moves back down. It’s like bending a paper clip over and over again. The thinner center section of butted spokes probably allows for a slightly slower retensioning over a straight spoke resulting on a slower tug on the head.
If you have that many spoke failures it's likely that the rest are all fatigued.
A recumbent can be harder on spokes because it's harder to unweight the bike like you can on an upright bike and tends to have even more of a rear weight bias. Still, a 36 spoke wheel on a 26" rim should be more than plenty strong for your application. Get a good wheelbuilder to rebuild your wheel with double butted spokes.
36 spokes is better than 32 for this applications but either many more spokes are needed or stronger spokes are needed. Rather than double butted spokes, I’d suggest triple butted ones like DT Alpine III 2.3/1.8/2.0mm spokes. They stronger than double butted and significantly stronger than single butted. Using them is like adding 4 (my estimate) to 10 spokes (Ric Hjertberg’s estimate). Here’s Hjertberg’s explanation on why using them is a good idea.
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Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
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Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
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#14
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My thoughts too - the spokes had a nick or gouge that started the fatigue. Once you got a crack, fatigue will go to work on it. Fatigue at the elbows or threads is to be expected under normal use given enough cycles, fatigue in the middle of the spoke needs something to get started.
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#15
Interested Backpacker
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Bike made the long journey to Williamsburg to see Matt at Contes. He is good and will make my wheel strong again.
As is the case with a lot of bike shops in this age of COVID, it may be a few weeks before I see the bike again. He was going to take a close look at alignment of rear derailleur and replace a few other items on the Tour EZ Sport. Thank you all for your input.
As is the case with a lot of bike shops in this age of COVID, it may be a few weeks before I see the bike again. He was going to take a close look at alignment of rear derailleur and replace a few other items on the Tour EZ Sport. Thank you all for your input.
#16
mosquito rancher
In my experience, spokes tend to break at the bend, on the drive side. Also, once spokes start breaking, they keep breaking—I'm pretty sure this is because of uneven spoke tension in the wheel. I would not be surprised if all the broken spokes were at 90° to each other.
Loosening and retightening all the spokes to restore even tension would be one way of dealing with this problem (this assumes that the wheel was correctly built in the first place, with inside and outside spokes where they should be). Buying a new wheel might actually be cheaper.
Loosening and retightening all the spokes to restore even tension would be one way of dealing with this problem (this assumes that the wheel was correctly built in the first place, with inside and outside spokes where they should be). Buying a new wheel might actually be cheaper.
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What, no pie plate comments? I thought for sure there would be a pie plate rant in here by now!
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