Bicycle Mechanics - stem the tide of broken spokes

my brother has an old schwinn super sport he rides to work 3x a week. 15mi round trip.

he needed a new rear wheel so i got him this one :http://www.amazon.com/gp/product/B000AO5FAQ/ref=oh_o00_s00_i00_details

(single wall alloy rim, 36h, 14g ss spokes)

when it arrived I detensioned the spokes and retrued it a couple of times. it was nice and straight, and stayed that way for several months so I thought all was well and I'd gotten lucky since i was a rookie at detensioning. but in the past 3 weeks he has broken 2 spokes. he is kind of big, 6'5 235.

is there anything I can do to make this wheel work for him or is he doomed to semi weekly trips to the lbs for a new spoke?

thanks

It's possible there's some substandard spokes on the new wheel, but that seems unlikely.

Have you stress-relieved the wheels? Check the usual sources (Brandt or Sheldon) for details. Several months is probably long enough for stress cracks to start popping the spokes on a new wheel. Go ahead and stress-relieve the wheel now; you may break a few spokes in the process, but if you do it right, those will be the last to pop for a very long time.

Spokes usually break from fatigue, usually caused by insufficient tension or improper stress relieving that results in insufficient tension. And a spoked wheel is like a chain - if one spoke has seen enough stress cycles to cause failure, all spokes have seen enough stress cycles to be close to failure. You can try to bring up the tension in all the spokes now, but it is likely too late and spokes will continue to break, possibly less frequently, but possibly not.

It is likely the wheel was not properly tensioned when new (machine built wheels seldom are) and you did not bring the tension up high enough folloed by stress releif when you re-tensioned it.

The best solution is new spokes and proper tensioning, stress relief, and re-tensioing to a high tension appropriate for your brother.

First of all broken spokes are like popcorn. First one or two break, but soon the time between breakage shortens as if they're all ready to break at once.

IMO, it's time to rebuild, and if you'll trust my advice you'll do the counter intuitave thing and use butted rather than plain gauge spokes. It seems odd that a thinner spoke can be stronger, but it's true. Spokes break at the elbow because the steel is only about 80% as strong in sheer (across the wire) as in tension. That makes the point at which the spoke leaves the hub sideways vulnerable.

As others have pointed out, it's metal fatigue that causes breakage, and the long thinner section of the spoke absorbs some of the deflections reducing the amount of strain at the elbow, thereby prolonging the fatigue life of the wheel. then all the other advice applies, you want a round, evenly tensioned wheel, of decently high tension. Beyond a certain point, added tension doesn't improve the wheel, so you wnat the right tension, not the highest.

It's possible there's some substandard spokes on the new wheel, but that seems unlikely.

Have you stress-relieved the wheels? Check the usual sources (Brandt or Sheldon) for details. Several months is probably long enough for stress cracks to start popping the spokes on a new wheel. Go ahead and stress-relieve the wheel now; you may break a few spokes in the process, but if you do it right, those will be the last to pop for a very long time.

yeah. i stress relieved them. that is what i meant when i typed retensioned. but, it was my first time doing it so might not have been as good a job. basically i squeezed them with gloves on like brandt suggests. then retrued and squeezed them again. i really thought i had done it right and gotten lucky when the wheel was true for so long. alas this appears not to be the case.

Francis, I trust your advice on the butted spokes. though wheel building is something I've never done. you think i need to take the whole thing apart or maybe just replace the drive side spokes with butted?

It's possible there's some substandard spokes on the new wheel, but that seems unlikely.



The link in the OP shows a complete rear wheel for $27. I would say it's likely that ALL of the spokes are "substandard." :D

My opinion: $27 rear wheel + 235 lb rider = lucky to have gotten several months of 3x per week riding.

To the OP, no matter how meticulous you were with re-tensioning the spokes, you're dealing with cheap stuff, and I'm sure you know that. For reliable wheels for a 235 lb rider, it's going to require a better quality wheel.

Francis, I trust your advice on the butted spokes. though wheel building is something I've never done. you think i need to take the whole thing apart or maybe just replace the drive side spokes with butted?

If anything you'd want the non-drive side to be butted. I build most GP wheels using two weights of butted spokes, 14/16g drive, 14/17g left.

There are lots of tutorials on wheelbuilding, and how to lace. If you lack confidence use a marker and put a dot on the four holes in the rim and corresponding holes in the hub, of the 4 spokes on either side of the valve hole. On the rim mark them for the flange and whether they go clockwise or counter clockwise. Then you can take the whole thing apart, and relace. If those 4 spokes are right all else follows automatically.

odds are your first wheel won't be as good as the one that follows, but if you take it slow it should be good enough with room to spare.

The link in the OP shows a complete rear wheel for $27. I would say it's likely that ALL of the spokes are "substandard." :D

My opinion: $27 rear wheel + 235 lb rider = lucky to have gotten several months of 3x per week riding.

To the OP, no matter how meticulous you were with re-tensioning the spokes, you're dealing with cheap stuff, and I'm sure you know that. For reliable wheels for a 235 lb rider, it's going to require a better quality wheel.

well, yeah. finding him a wheel with 36 ss spokes and aluminum rims was the best i could do on a budget. I hoped it would be fine. i am near 200 and have never had issue with budget wheels.

A 235lb rider and a single walled rim, on a commuter bike is a bad recipe. A stouter double walled rim would help this situation greatly.

A 235lb rider and a single walled rim, on a commuter bike is a bad recipe. A stouter double walled rim would help this situation greatly.

i knew a double wall was preferred, but would this make a difference if everything else was still the same? ie wouldnt the spokes till be breaking

i knew a double wall was preferred, but would this make a difference if everything else was still the same? ie wouldnt the spokes till be breaking

Rim strength only factors to the extent that it allows stronger or fewer spokes. If all else is the same and the rim is adequately strong for the spokes, than it isn't a factor. The main advantage of double wall rims, is a higher strength to weight ratio, which is usually used to lower weight.

235 isn't all that heavy for a rider, though it would exclude some super light stuff. many tandem riders are riding 36h DB rear wheels very successfully for years. I weigh 190 (or more) and ride 310 gram tubular rims built with light spokes, and my wheels all last trouble free until a major crash.

Rider habits are a factor though, and a heavy rider should learn to help the bike by developing smooth pedaling technique, not overly rocking the frame when climbing steep hills, and helping the bike through rough patches by lifting out of the saddle and using flexed knees as shock absorbers so only the bike had to bounce up and down, not the full 250+ unit.

Rim strength only factors to the extent that it allows stronger or fewer spokes. If all else is the same and the rim is adequately strong for the spokes, than it isn't a factor. The main advantage of double wall rims, is a higher strength to weight ratio, which is usually used to lower weight.

235 isn't all that heavy for a rider, though it would exclude some super light stuff. many tandem riders are riding 36h DB rear wheels very successfully for years. I weigh 190 (or more) and ride 310 gram tubular rims built with light spokes, and my wheels all last trouble free until a major crash.

Rider habits are a factor though, and a heavy rider should learn to help the bike by developing smooth pedaling technique, not overly rocking the frame when climbing steep hills, and helping the bike through rough patches by lifting out of the saddle and using flexed knees as shock absorbers so only the bike had to bounce up and down, not the full 250+ unit.


good advice on the technique. I emphasized this to him when he started bc he hadnt ridden for 15yrs or so. the wheels remaining perfectly true until the broken spokes I took as an indication he was riding it fairly gently.

final question: if I am going to rebuild the wheel would it make sense to replace everything new spokes,hubs, rims? build it myself or just buy him a better wheel? I dont mind attempting the build, but if getting a new wheel is less money then that would make sense.

in other words, what's the best way (and least expensive) to get my fat ass brother a wheel that will work for him? haha

part of getting down to a wheel selling for $27 is using the cheapest materials
for all parts.

Even the wire that is used to form the spokes can be full of contaminants ..
like slag.

in other words, what's the best way (and least expensive) to get my fat ass brother a wheel that will work for him? haha

this is a question with too many variables. First of all there's rarely a need to replace the hub, but you may want to service it while you're at it. I've got hubs that are on the 5th or more wheel (lost count) and still fine. OTOH if the hub is garden variety, it may be worth than the savings involved in a complete prebuilt wheel. As for the rim, I never reuse rims or spokes, but many do OK doing that so it's a toss up. The deciding factor might be the condition of the rim, and you can't know for sure until you unlace it and lay it flat on a table.

Comparing buying vs building is tricky, certainly you could build a better wheel than almost any GV wheel bought complete. If you paid for a serious wheel form someone like mrrabbit, or the folks at Yellow Jersey, you'd get as good as you could build. The real question is how good a job can you do. That's a big variable, so start by getting the numbers, call Yellow Jersey, and a few builders and find out what a decent wheel would cost, compare that to the cost of another GV wheel which will probably last about as long as this one, then compare to the cost of rim and spokes, and decide which way you want to go.

Even the wire that is used to form the spokes can be full of contaminants ..
like slag.

Do you just make this stuff up?

That reminds me of a few years ago when Bicycling magazine, said about chain lubes---(not exact quote but the gist in there--- "don't use motor oil to lube a chain because it's full of fine metal particles that will accelerate wear".

I wrote them and suggested they let the folks at Ferrari know because it would be important to them.

Batch of spokes , nameless . China . have been showing up, at LBS,
so get replaced. as needed.. Low end material choice presumed.
..given: QC is a cost ..



"don't use, ->used<-
motor oil to lube a chain because it's full of fine metal particles that will accelerate wear".

one little word

Batch of spokes , nameless . China . have been showing up, at LBS, so get replaced.


Every time a bike manufacturer includes improperly tensioned or stress relieved wheels with their bikes, the story of the 'bad batch' of spokes gets hurled around. I'm not saying that a bad batch of spokes is impossible or never happens, but improperly tensioned wheels are 1000 times more likely and more common in reality.

Batch of spokes , nameless . China . have been showing up, at LBS,
so get replaced. as needed.. Low end material choice presumed.
..given: QC is a cost ..

No doubt there's a large spectrum in spoke wire quality, but it isn't from impurities and certainly not because cheap wire contains slag. Like with frame tubing, sprint material, hand tool, cutlery, and so on, there are better materials and cheaper materials, and there are even differences in material at the premium level. But even the cheapest wire like that used to make paper clips is of good uniformity and consistency, it's just of a different alloy.

Wire forming is a high speed highly automated process, and the costs involved in working with inconsistent wire would dwarf any possible savings.



->used<-

one little word

Yes, the information might have been more accurate if that said that, but they didn't.

My local bike shop charges $25 shop labor to build a wheel. Hardly worth my time to put it together, plus they handle the warranty if there is an issue.

Tom

Rim strength only factors to the extent that it allows stronger or fewer spokes. If all else is the same and the rim is adequately strong for the spokes, than it isn't a factor. The main advantage of double wall rims, is a higher strength to weight ratio, which is usually used to lower weight.

Back to the rims: I disagree and believe the rim plays a big role in this situation. Most of the budget wheels rolling through our shop with this same problem are breaking spokes at the hub flange: popping the heads right off. Since these wheels are built with straight gauge spokes, and single walled rims, when the rim deflects from a road impact, it transfers that load down the spoke and finds the weakest spot to break: the bend at the hub. A double walled rim would add strength to the wheel and distribute the effects of and impact across multiple spokes.

But I agree that even a big/ heavy rider can ride "light" if they know how to and have success with these wheels for a long time.

any way $28 wheel is not going to have Swiss or Belgian sourced spokes ..

my brother has an old schwinn super sport he rides to work 3x a week. 15mi round trip.
is there anything I can do to make this wheel work for him or is he doomed to semi weekly trips to the lbs for a new spoke?


Replace all the spokes in the failing side(s) (they're all approaching their fatigue limit) with quality butted spokes (DT Competition 2.0/1.8) and brass nipples, true, tension, and stress relieve per _The Bicycle Wheel_.

Taking the opportunity to install a nice double walled rim at the same time is a fine idea too.

any way $28 wheel is not going to have Swiss or Belgian sourced spokes ..

CN, Pillar,......

And those are the good ones that have names.

And there is always Wheelsmith.

To OP, I know the boat you are in. Trying to not spend more than the bike is worth to get it running. Finding a new 27" wheel with db spokes is a tough task. These guys do some customs so I would call and ask the cost of buying just the rear of this set built with db spokes: http://www.bicyclewheels.com/merchant.mvc?Screen=PROD&Store_Code=B&Product_Code=27FW&Category_Code=R27

You may consider talking to the wheelbuilder at you local shop and having them recommended a rim and spokes and have him/her lace it up for you. A quality wheelbuilder will stand behind their work and if the new build fails, you can bring it back to the shop.
I appreciate the ease and convenience of online shopping, and the obvious savings to be had, but this is where the local bike shop shines and what they are there for and want to do. Take that rant as you will from a wheel builder at a local bike shop.

thanks for the link. something like that looks like a solid step up and not crazy expensive. would be nice if they were local.

as FBinNY wrote, lots of variables. all swimming around in my head. I'm leaning towards getting a local shop to build him a wheel. if it were for me, I'd likely undertake it myself and then learn from the consequences. and although paying 2 or 3x what the bike cost for a wheel is a little difficult, as much as he rides it would be worth it if the problems ended. esp since he's dropped 40bucks on repairing it already.

edit: interesting how i came to that conclusion as marcusbandito was typing up very similar logic.

You may consider talking to the wheelbuilder at you local shop and having them recommended a rim and spokes and have him/her lace it up for you. A quality wheelbuilder will stand behind their work and if the new build fails, you can bring it back to the shop.
I appreciate the ease and convenience of online shopping, and the obvious savings to be had, but this is where the local bike shop shines and what they are there for and want to do. Take that rant as you will from a wheel builder at a local bike shop.

You raise valid points and all things being equal I'd also suggest going to the local shop. But all things aren't equal, even forgetting about price. Having spent my life as a supplier to shops, I've visited a good many shops and spoken to countless mechanics, and the spectrum of skill and knowledge is wider than that of visible light. There are many top flight people there, but there are an equal number of hacks or worse. There's also a lot of misinformation, and what I call Voodoo practices.

Speaking to end users who do their own work, the number one reason cited why isn't to save money, but because of disappointment in the quality of the local shop mechanic's work.

I apologize to all the skilled shop mechanics out there, and there are many, but the large number of hacks reflects badly on all of you. If the OP's local shop has a good reputation for skilled work, it's his best bet. But if not, he's shopping blind and possibly be paying a premium price and not getting what he needs.






If the OP can find a local builder

..when the rim deflects from a road impact, it transfers that load down the spoke and finds the weakest spot to break:

Dont think the mechanics work that way, as spokes cant take any load in compression.
When the rim deflects (vertically) from road impact, the spokes in the affected zone lose tension - not add to it. The rest of the spokes pick up some load, but its so well distributed that on a 36H wheel it can even be hard to measure the increase - at least as seen when JRA. What a stiffer rim does is reduce the amount of vertical deflection(for a given load) making the spoke see less of a cyclic change in tension - which offers a degree of fatigue protection.

I guess you could argue the case that theres a spike in tension as the rim springs back, which might contribute to breaking a spoke. I have no idea if aluminium would spring back snappily enough for the dynamics of that to be significant.

Dont think the mechanics work that way, as spokes cant take any load in compression.
When the rim deflects (vertically) from road impact, the spokes in the affected zone lose tension - not add to it. The rest of the spokes pick up some load, but its so well distributed that on a 36H wheel it can even be hard to measure the increase - at least as seen when JRA. What a stiffer rim does is reduce the amount of vertical deflection(for a given load) making the spoke see less of a cyclic change in tension - which offers a degree of fatigue protection.

I guess you could argue the case that theres a spike in tension as the rim springs back, which might contribute to breaking a spoke. I have no idea if aluminium would spring back snappily enough for the dynamics of that to be significant.


Well said.

I think you should secretly follow your brother to work and check his riding style. if he bumps up and down curbs and bounces from pothole to pothole that could be the issue.

I think you should secretly follow your brother to work and check his riding style. if he bumps up and down curbs and bounces from pothole to pothole that could be the issue.

haha. true. i sent him a big list of riding tips when he started, and he's a bit of an oaf but he aint dumb. dont you think if he were hitting potholes and curbs the wheels would have been out of true sooner, with or without broken spokes ?

Just my recent experience - been putting a bunch of scouts through the Cycling Merit Badge. One boy and his Dad broke a spoke at the beginning of one of the rides. Got picked up by sag-wagon and took him back to the start. I later repaired it. But really strange. It was a stress fracture smack in the middle of the spoke. Not the elbow, not the nipple. But right in the middle like it was sheared or bent then broken during the ride. It was a pulling spoke on the rear side. With lots of bikes in my free clinic, I didn't think much about it and so I just pulled the cassette off, pushed a new spoke in there and got the bike repaired and pushed it out; his Dad took the bike home. The kid was riding around in his neighbourhood and broke another spoke, said his Dad not too long later. Drive side again, but not a pulling spoke. Again broken in the middle. Dad brought the bike back, I then replaced 18 spokes on the drive side. Didn't want to mess with this again. And this kid, while 6 ft tall, was skinny like a toothpick. But I had 263mm in stock and dang, I didn't want this bike back in my garage. But, a few days later, the bike shows up again at my house. Broken FRONT spoke this time. No WAY!!!

I then watched the Dad pull the bike out of the back. You see, he sticks the bike in the trunk. It's a Volvo sedan. Fairly big trunk. But the bike doesn't fit; one the wheels hangs partially out. Sometimes the Dad loads the bike rear wheel in first, sometimes, front wheel in. He doesn't put the rear seat backs down. And he doesn't secure the trunk lid, so it slams down on the wheel and that's the way the Dad hauls the bike. He doesn't pad the bike or pad the frame. And he doesn't try to bungee the lid. He claims the wind flow over the car keeps the lid down and he's just a mile away from me. (Sigh, smile dryly and roll my eyes).

So looking at the car's trunk latch and the lid, I see a lot of little chips and dings on the edge of the trunk lid and now looking closely at the spokes on the bike, I see nicks on the spokes, I guess from multiple impacts. I suggested that it's likely the trunk lid and lock latch impact are the cause of damage to the wheel and to secure that the lid and pad the wheel or more spokes will break, or better yet, I suggested maybe a bike carrier.

But I guess what I should have done was to slow-down, take a look at the failure mode of the spoke and ask what could have caused the spoke to break that way. I wouldn't have wasted the time having that bike in my garage multiple times.

good story. might as well ask him if anything slams into the spokes regularly. he has a 3yr old boy so it's not out of the question