pepperbelly

I was riding yesterday on my normal route through town. At one spot at the spot where a concrete valley meets the asphalt I rode over a hole. It didn’t look big but I heard a pop. Broken spoke.
I am an old fat rider-260 pounds and retired and working on it.
Is it possible I am too heavy for my Specialized Roubaix? The previous owner had replaced the rims with DT Swiss. I’m not sure what spokes.

JohnDThompson 

32 or 36 spoke wheels ought to hold you fine. Are yours perhaps weight-weenie, low spoke count type wheels?

Replace the spoke and keep riding. If others spokes fail, consider rebuilding or replacing the wheels.

_ForceD_

Sometimes spokes just go. I’ve had them break on perfectly smooth roads.

Dan

Crankycrank

Which model of DT rims are they and how many spokes? 260lbs is maybe a little heavy for some lightweight-low spoke count wheels. Did you derail your your chain into the spokes at any time? If so and it caused any gouges in the spokes that can cause premature breakage as well.

CliffordK

Also use as large of tires as the bike will take (with a bit of a buffer). 32mm? 35mm?

Andrew R Stewart 

As anyone who is at the ends of the weight bell curve knows small people don't stress their stuff as much as most and big people see more wear and stress then the average. So it's not about being too big for this or that part it's about how much/little life span is acceptable. The weight limits you see stated by manufacturers is mostly driven by their liability lawyers/insurance co.

If this is the first time a spoke has broken and if the rim/wheel is otherwise in good condition (other spokes, bearings, brake track wear, no rim dents or cracks) I would suggest replacing the spoke and continuing to ride the wheel. BUT I would also be planning the next step which is wheel replacement. I would suggest more spokes, shy away from wheels aimed at the athletic/competitive market and fit the largest tire you can. Andy

cyccommute 

For the bike? No. For the wheels, probably.

And therein lies the problem. What broke on the wheel? The rim?

Rhetorical question, of course. The spoke is what broke so why are you worried about the rim? The rim does practically nothing for wheel strength. It is a convenient place to put a tire and a convenient way to hold the spokes together. The item that broke…i.e. the spoke…does all the heavy lifting when it comes to wheel strength. The fewer spokes you have, the more heavy lifting each spoke does.

Even if you have few spokes, for your application, you should be using a triple butted spoke like the DT Alpine III. This article explains why. They are stronger and more durable. More of them is better but even with low spoke count wheels, they are stronger then straight gauge or even double butted spokes. Unfortunately, you won’t find them in OEM or even that many custom wheels. You may have to build them yourself or find a wheel builder that will listen your needs.

Finally, as to tires, they do little to alleviate the problem of broken spokes. Spokes don’t break because of sudden impact. Spokes break because of the long term action of loading and unloading as the wheel spins. The tire has little to no effect on that loading and unloading over time. Stronger spokes have an impact but not tires nor the way you ride.

pepperbelly

the tires that came on it are 28mm.

pepperbelly

Thanks everybody. I will see it it happenes again.
This was the first time I had one break.

CliffordK

That may be OK.

But, if 32's or 35's will fit, then that will give you just a little extra cushion (and allow slightly lower pressure).

Or, you could put a 32 on the rear now, and keep the 28's for the front for later.

pepperbelly

i will need to measure the clearance.
These tires are stamped 85psi.

CliffordK

85 PSI probably isn't bad. But, there are pressure/weight charts. And, you may not need the same pressure in both the front and rear tires.

Increase pressure if you feel the tire bottoming out on bumps or you're getting pinch flats.

Front and rear pressures generally don't have to be the same.

https://cycleschinook.com/tire-pressure-calculator/

Ok, so I put in 280 lbs (person + bike)
"Gravel Bike"

28mm tires
15% drop (tube), Rear 108 psi, Front 96 psi
20% drop (tubeless), Rear 82 psi, Front 73 psi

If you go to 32mm tires, you get:
15% drop (tube), Rear 88 psi, Front 78 psi
20% drop (tubeless), Rear 67 psi, Front 60 psi

Again, choose a pressure that isn't giving you problems.

cpach

One broken spoke is can be a fluke. That said, weight is just one variable affecting spoke fatigue--riding style and road conditions also play a huge role. That said, at your weight, it would probably be advisable to get stronger wheels if you keep breaking spokes. I'd recommend 32 or 36 spokes on the rear (32 is fine for the front) on a modestly burly rim with butted spokes by an experienced wheel builder if the budget allows. The high, even tension of a good build will do as much (or more) good than the component choices.

zandoval 

My ChroMo FUJI took me from 287 to 230 over a year of ridding. At 260 I started popping spokes on my rear tire. I think they just wore out as they popped at the neck and the rim was fine. I went to a new wheel set 36 spokes 14ga stainless spokes and all has been well. I got my machine made wheel set for a good price. When ever I get a machine made wheel set I loosen um up and then re-tune them but usually that is just over kill.

Don't go crazy on fancy wheel sets. Get a strong reliable set and ride, ride, ride...

pepperbelly

The spoke broke in the middle.

Koyote

One broken spoke gets replaced...And rest of wheel gets checked for spoke tension and trueness. If a second spoke breaks, I get a new wheel. Life is too short to spend much time walking a bike home.

Koyote

That spoke was damaged, then. Check adjacent spokes for any damage.

cyccommute 

I have never understood this idea that picking the right components…i.e. strong spokes…has anything to do with a bad wheel build. Yes, even tension makes for a good build but even tension on stronger spokes makes for and every better build. Don’t assume that just because triple butted spokes are chosen that the builder won’t build properly.

And, frankly, the only component that matters in a good wheel build is the spokes. Pick whatever rim or hub you want. They won’t make for a strong wheel.

davidad

At 260 pounds engine and 25 pounds bike weight you need at least 36 double butted spokes.

cpach

You misunderstand me. I just mean that high, even tension is very important. In my experience, well built wheels of inexpensive parts break less spokes than many factory wheels with better parts (including various butted spokes) and very poor build quality. I would in fact generally assume any builder selecting triple butted spokes would do an at least reasonable quality job. And I'm generally on your side, I think triple butted (and even 13/14GA single butted) spokes are great, and build with them frequently.

I disagree with you on the contribution or rims--good rims can be built to a higher dimensional tolerance with lower tension deviation, effecting spoke longevity, and also they have some effect on system deflection, and certainly have a pretty significant effect on lateral rigidity. Asymmetrical rims can even spoke tensions. Hubs dimensions can also have some effect on tension balance on dished wheels and on lateral rigidity, although the range of variation here is pretty slight and is mostly unrelated to cost. I would agree that the spokes itself are the component that has by far the greatest impact on spoke fatigue resistance.

cyccommute 

The real problem with factory wheels is because they are using the weakest (and cheapest) spoke they can. A straight gauge spoke is the weakest of the lot.

Let’s start with your comment on “good rims”. There are very few modern rims that can be classified as “bad”. You’d have to go way down into the basement to find anything that is weak or prone to being noodly. Single walled rims come to mind but those are hard to find…I tried for another discussion and there just aren’t any for the aftermarket wheel. There are some differences in rims but a double walled rim is going to fit in the parameters that you lay out.

Asymmetrical rims do indeed even out spoke tension but the benefit is from the even spoke tension but the rim isn’t “stronger”.

Hub dimensions have zero to do with spoke and, thus, wheel strength. As you noted, flange dimensions don’t vary all that much in modern hubs…they are much wider than they were 20+ years ago. An argument could be made that shorter spokes are stronger but the variation due to the flange dimension is very small…on the order of millimeters. There’s a huge difference (about 30mm) between a 700C and a 26” wheel which, again, could result in a stronger wheel.

The main reason that I say a rim doesn’t matter is because the rim isn’t attached to the spokes. The rim floats on the spokes and any impact will only result in deformation of the rim but not of the spoke. That’s also the reason that I said the tire width doesn’t matter. Shocks to the tire and wheel don’t necessarily translate to the spokes. The rim would have to deflect almost 10 cm on most rims for the spoke to even come close to touching the tire which would translate energy to the spoke. A rim that deflects that much will have other issues unrelated to the spoke.

Consider this thought experiment: A steel rim is arguable the strongest, stiffest rim available. It doesn’t suffer from any of the issues that aluminum does…it’s tough to blip, its extremely rigid, and it will not crack do to spoke tension or due to flexing due to the loading/unloading of the spokes. Now build a wheel with that rim and the lightest spokes you can get…let’s say a 1.8mm straight gauge spoke. Do you really think that will be a stronger wheel than a wheel built with an extremely lightweight rim and triple butted spokes?

Further, a broken rim is not an indicator of a dead wheel. Replacing a rim relatively simple and a wheel can last through several rims. Break a spoke and the wheel is suspect. Break two spokes and you should be thinking about wheel replacement. Break 3 spokes and you are well on your way towards buying spokes by the gross.

A wider, heavier rim is just heavier. It isn’t stronger in any of your parameters above. I use the lightest rims I can find and my rims don’t suffer in either lateral or vertical rigidity. I don’t suffer broken wheels because I use better spokes.

pdlamb

Not in my experience, although that experience is somewhat dated, in that I haven't bought a factory wheel in 10 years or more and those were mid-range or lower. It's possible factories have been updated in that time, or that higher end factories have better builds.

With those caveats out of the way, I've broken spokes on factory built wheels in less than 500 miles, and around 1000 miles. After replacing those broken spokes, the remaining spokes were fine for thousands of miles. Why did the rest of the OEM spokes survive? I think the two factors that made the difference were raising the tension and stress relieving the spokes.

cyccommute 

Straight gauge spokes are demonstrably weaker than double butted spokes and double butted spokes are demonstrably weaker than triple butted. Pillar spokes is the only place I can find strength testing data but their results are quite clear

Straight gauge
Image 5-11-18 at 1.41 PM by Stuart Black, on Flickr

Double butted

Image 5-11-18 at 1.44 PM by Stuart Black, on Flickr

Triple butted

Image 5-11-18 at 1.43 PM by Stuart Black, on Flickr

The triple butted spokes (2018 in the third graph) have a breaking strength of 340 kgf from the graph. Double butted (1415 in the second graph) break around 310 kgf and straight (P14) break around 270 kgf. Between the double and straight, that’s a 14% increase in strength. Between the triple and double it’s a 9% increase in strength. Between the triple and straight, there is a 25% increase.

Tension and stress relieving get too much credit. Yes, they are important but spoke strength is as important, if not more so. I built a lot of wheels and broke a lot of spokes prior to going to triple butted spokes in all my builds. I use high tension and stress relieve and have for long before I started using triple butted spokes. The tension I use hasn’t increased nor did I change the way in which I stress relieve my wheels. But once I switched to triple butted spokes, spoke breakage went to zero and has stayed there for 20 years or more.

Triple butted spokes don’t hurt and they help a whole lot. There really is no downside to using them.

pdlamb

I'm not sure what the relevance of breaking strength is above what's used in ordinary bicycle spokes. I don't remember seeing a recommendation for more than 125 kgf tension on a spoke, and most are in the 95-115 kgf range. If I'm reading the (slightly goofy) scale right, even a 15 gauge straight spoke breaks around 216 kgf; that's already about 73% margin to 125 kgf. What do you buy with the extra triple butted margin?

Again, not my experience. Double butted is easier to build with because of the elasticity of the central band, but straight spokes with proper tension and stress relief also work well. Based on what I've seen, the triple butted preference looks like a case of "Perfect is the enemy of good enough."

Is it possible the metallurgy in all (brand name) spokes has improved since you went exclusively to triple butted?

cyccommute 

Don’t look at the charts with respect to the tension in a wheel build. That is not what they are for. The amount of force needed to break a spoke is proportional to the durability of the spoke. If it takes more force to break, the spoke will take longer to fatigue and break. From the link I posted in post 7,


That hasn’t been my experience at all. Not personally and not in a co-op setting nor even here on the Bike Forums. Broken spokes are probably number 3 in questions here behind chains and derailers and they are certainly high on the list of things that get fixed at my local co-op. My issues with spokes breakage covered a lot of time…from the late 80s to early 2000s. My experience is very much in line with Hjertberg’s in that changing to triple butted spokes made the problem go away.

Not significantly, no.