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Heads snapping off spokes

Old 06-26-21, 08:16 AM
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Heads snapping off spokes

Hey guys. I've got a wheel on a bike I support (family member) that has broken 2 spokes in 2 weeks. After the first one, I happened to have a spare of the right length so put the spare spoke in and trued the wheel.

Both spokes the head snapped off and the spoke pulled through the hub. Both drive side head-out trailing spokes.

This is the OEM wheel on a Raleigh USA Merit road bike. (Rim brake) It's about 5 years old, hasn't seen excessively high mileage, though the rider is a little on the clyde side, and recently been training a lot more, developing more power and fitness.

What can I do to get the wheel reliable again? Any suggestions?
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Old 06-26-21, 08:41 AM
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It's hard to say but first thought is inconsistent spoke tension or maybe just plain crappy spokes.

If you have a spoke tension gauge, or some other means of assuring all spokes are equally tensioned to an appropriate tightness, that would be a good place to start. If that doesn't work I'd rebuild the wheel with some quality spokes from DT or Sapim. 14/15's for DS. You might be able to get away with only doing the DS if money is tight.
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Old 06-26-21, 08:43 AM
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Need more info on the wheels if you can, brand, how many spokes, front-rear-both, riders approximate weight. If it's an inexpensive wheel with few spokes that itself could be the problem for a heavy rider. Could be spokes were loose and caused the failure. Let us know and we can give you a better answer.
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Old 06-26-21, 09:00 AM
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Originally Posted by Viich View Post
Hey guys. I've got a wheel on a bike I support (family member) that has broken 2 spokes in 2 weeks. After the first one, I happened to have a spare of the right length so put the spare spoke in and trued the wheel.

Both spokes the head snapped off and the spoke pulled through the hub. Both drive side head-out trailing spokes.

This is the OEM wheel on a Raleigh USA Merit road bike. (Rim brake) It's about 5 years old, hasn't seen excessively high mileage, though the rider is a little on the clyde side, and recently been training a lot more, developing more power and fitness.
Yours is a fairly common problem. Itís related to spoke tension but it is also caused by other factors. Straight gauge spokes (one diameter from the head to threads) are more prone to the problem because they arenít as elastic as butted spokes. Heavier riders and/or people carrying heavier loads stress the spokes more and are thus more prone to breakage. Thatís because the load puts more stress on the spoke but also because the load causes the rim to deflect more when it is at the contact patch which cause the spokes to loosen more than with a lighter rider. The head of the spoke is detension/retensioned constantly. Itís something like constantly bending a paper clip, eventually it is going to fatigue and break.

What can I do to get the wheel reliable again? Any suggestions?
With these spokes? Probably not. For the best wheel, rebuild with stronger spokes like DT Alpine III or other triple butted spokes. The heads are thicker by 0.3mm which increases their strength by about 50%. Additionally, the larger sized spoke bend means that the spoke fits tighter in the hub so that it move less during the detension/retensioning process which is going to occur no matter what you do.

That strength comes at the price of only a slight increase in weight Öabout 7g per wheel. The spokes are more expensive but cheaper than several wheels youíd replace with lighter spokes.
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Old 06-26-21, 11:21 AM
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Originally Posted by cyccommute View Post
Yours is a fairly common problem. It’s related to spoke tension but it is also caused by other factors. Straight gauge spokes (one diameter from the head to threads) are more prone to the problem because they aren’t as elastic as butted spokes. Heavier riders and/or people carrying heavier loads stress the spokes more and are thus more prone to breakage. That’s because the load puts more stress on the spoke but also because the load causes the rim to deflect more when it is at the contact patch which cause the spokes to loosen more than with a lighter rider. The head of the spoke is detension/retensioned constantly. It’s something like constantly bending a paper clip, eventually it is going to fatigue and break.

With these spokes? Probably not. For the best wheel, rebuild with stronger spokes like DT Alpine III or other triple butted spokes. The heads are thicker by 0.3mm which increases their strength by about 50%. Additionally, the larger sized spoke bend means that the spoke fits tighter in the hub so that it move less during the detension/retensioning process which is going to occur no matter what you do.
That strength comes at the price of only a slight increase in weight …about 7g per wheel. The spokes are more expensive but cheaper than several wheels you’d replace with lighter spokes.
Originally Posted by Crankycrank View Post
Need more info on the wheels if you can, brand, how many spokes, front-rear-both, riders approximate weight. If it's an inexpensive wheel with few spokes that itself could be the problem for a heavy rider. Could be spokes were loose and caused the failure. Let us know and we can give you a better answer.
Originally Posted by Nessism View Post
It's hard to say but first thought is inconsistent spoke tension or maybe just plain crappy spokes.
If you have a spoke tension gauge, or some other means of assuring all spokes are equally tensioned to an appropriate tightness, that would be a good place to start. If that doesn't work I'd rebuild the wheel with some quality spokes from DT or Sapim. 14/15's for DS. You might be able to get away with only doing the DS if money is tight.
It's a "Weinmann GMax" wheel - just OEM-spec on the Raleigh Merit 1 from 2016. Hub is unlabelled. 36spoke front and rear, but straight guage. Like I said, the 2 spokes that snapped so far are both drive side trailing (rear wheel)

The hub probably isn't worth a completely new set of spokes, unfortunately, and I'm building a new bike for the same rider right now anyway. If we keep having problems I'll likely build a wheel with Sapim Force spokes (My experience is mostly with Sapim spokes, easier to get here, I find)

Last edited by Viich; 06-28-21 at 03:13 PM.
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Old 06-26-21, 11:27 AM
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You need a new wheel. Once you break your second spoke you will end up breaking more and more and chasing around that wheel. It is a cheap wheel on a cheap bike, it was not designed to last. However keep in mind the Merit doesn't have a ton of a value so you may consider looking at different bikes in the near future so that $200 rear wheel that will certainly be of a bit better quality might be worth around the same as the bike if not maybe more depending on the overall condition and your market and such.

What I would do is talk with your friend and see what their next bike might be and see if you can build a compatible wheel for both. With rim brakes it might be tougher as most production stuff has gone disc but if they go a little more off the beaten path and look at some custom stuff you might get rim brakes.

Sapim makes excellent spokes, most of my wheels are Force or Strong spokes and brass Secure Lock nipples and no issues.
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Old 06-27-21, 07:40 AM
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My Rayleigh Tamland, also about 5 years old, has Weinmann rims and used to have a spoke breaking problem on the rear wheel. I'm 240# and do overnights on rail trails, so heavy load on bad roads. The stock wheel was breaking the spokes at the nipples. After replacing a few spokes and getting tired of dealing with the crappy rear hub I finally upgraded the rear hub and put in a new set of Wheelsmith double butted spokes, but reused the rim. When that started breaking spokes at the J bends I bought a Park tool spoke tension meter to check my work, only to find the spoke tension was spot on.

At that point I got pissed, threw the Weinman rim in a recycle bin and laced up a Mavic A719 rim with Sapim double butted spokes on the brake side and Alpine III triple butted on the drive side like cyccommute suggested.

No longer breaking spokes, LOL.
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Old 06-27-21, 10:43 AM
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Wow, I finally topped someone... Last week, I broke two spokes (in my rear wheel) in an hour.
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Old 06-27-21, 04:49 PM
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Originally Posted by Viich View Post
Hey guys. I've got a wheel on a bike I support (family member) that has broken 2 spokes in 2 weeks. After the first one, I happened to have a spare of the right length so put the spare spoke in and trued the wheel.

Both spokes the head snapped off and the spoke pulled through the hub. Both drive side head-out trailing spokes.

This is the OEM wheel on a Raleigh USA Merit road bike. (Rim brake) It's about 5 years old, hasn't seen excessively high mileage, though the rider is a little on the clyde side, and recently been training a lot more, developing more power and fitness.

What can I do to get the wheel reliable again? Any suggestions?
How much stress-relieving did you do when you re-trued the wheel? After reading Jobst Brandt's old posts about it, I realized one of the goals of the process is to identify (and snap) weak spokes before sending the wheel back out into the field.
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Old 06-28-21, 02:54 PM
  #10  
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Originally Posted by ThermionicScott View Post
How much stress-relieving did you do when you re-trued the wheel? After reading Jobst Brandt's old posts about it, I realized one of the goals of the process is to identify (and snap) weak spokes before sending the wheel back out into the field.
Probably not a lot, but in my defense, I only had the one spoke on hand....... I didn't WANT to find any more right then.
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