PeteHski

I've never broken a spoke (front or rear) in 50 years of cycling on/off road. But last summer I did witness another rider's rear spoke break when the guy I was following up a wet & slippery 20% slope suddenly tried to downshift (no idea why he wasn't already in his lowest gear by that point) and then stomped hard on the pedals. His back wheel momentarily slipped and then when it regained a bit of traction - crack!

79pmooney

I have. Once or twice pure miles. Lesser spokes. The early SS ones popped heads when they were having a bad day. In every box of 100 zinc plated DB Robergels, 3 or 4 would break; just because. Broke 8 on one side and 1 on the other simultaneously once. (There was a QR from another bike in there.) I've broken nipples when the spokes were not quite long enough. And had a run of spokes that broke across the threads just below the nipples.

Want stories for the internet? Ride 200,000 miles. I promise you will gather a few.

frogman

Same here. I guess we have to live with the shame.

rsbob 

only one on a factory wheel when I hit a good sized pothole That was probably 35 years ago,

broke a back spoke on my MTB a week ago and wasn’t doing anything too crazy.

Russ Roth

I want to say yes but excepting crashes I'm not certain its really true so maybe one.

With modern rims I will say that 36 spokes is more than needed unless you're north of 300, even my touring bike is only 32 though the rear wheel is built single butted 13/14 for spoke strength at the head. Front is regular butted.

Darth Lefty 

I have been curious about this and disc brake wheels. A front disc incurs several times more torque and weight transfer than a rear cog but only occasionally instead of constantly and rhythmically

KerryIrons

Yes, once in well over 300K miles of riding. Good quality spokes on a good quality hub with a good quality rim built well. It just broke (at the hub). Grain defect in the spoke I suspect. Absent a crash it is a VERY rare experience with quality equipment.

63rickert

What? If you never broke a front spoke you need to ride more.

Note that Greg Lemond won his second world championship at Altenrhein, 1989, with two broken spokes in his front wheel. In the mountains. In the rain. Safe to assume Greg had a properly built wheel and a low mileage or new wheel. It happens.

BlazingPedals

I have, although my situation is a little different than most. I have a highracer recumbent. I broke a front spoke on a Velocity wheelset. After having the spoke replaced, I broke another spoke on the same wheel a few weeks later. Figuring there's something wrong with the wheel build, I swapped to another brand-new Velocity wheel. Nope, the next week I broke another spoke. At that point I had the most recently-affected wheel completely respoked with heavier spokes. It was rock-solid after that. Both wheels were 20-spoke front wheels and I was at 200 pounds riding smooth pavement. I have since retired that wheelset to my spares and now use a set of Roval wheels with similar spoke counts, which have been problem-free for 5-6 years.

I can only figure that putting the pedaling forces in front of and over the wheel caused extra stress on it and the wheel just needed to be a little more heavily-built.

DDzBike

No front spokes yet, but I did have a nipple let go last spring

rsbob 

partial credit.

cyccommute 

A whole lot of people have the wrong idea about what breaks spokes. Impacts aren’t going to break a spoke. Spokes aren’t “attached” to the rim. The rim holds the end of the spoke but put enough force on the rim to bend it and it simply slides up the spoke. Bicycle spokes are only under tension and never under compression.

Spokes on bikes break because of the asymmetric loads on the spokes because of our use of multigear systems. The spokes on the rear wheel are under very different tension depending on the side of the wheel they happen to be on. There are three actions that put stress on the spokes…pedaling, cornering, and just rolling down the road. (Braking is in there also but it’s the same as rolling down the road with minus sign.) Rolling down the road (and braking) probably put the least amount of stress on the spokes but they are of high frequency. Each time a spoke hits the bottom of the wheel, the tension on the spoke is reduced to its lowest level. As the spoke moves away from the bottom of the wheel, the tension increases. This happens roughly 140 times per minute at 12 mph on a 700C wheel. For a one hour ride, a spoke is stress/distressed over 16,500 times. Low spoke tension can cause this flex to be more pronounced than high tension. The left wheel in the picture below illustrates this detensioning in an exaggerated manner.


During braking and pedaling, the spokes are subjected force as well…and a different kind of bending…as the hub tires to spin the spoke ahead of the rim. The flex in the spoke is different from the flex of loading and unloading.

Cornering probably is the largest force on the spoke because the spoke is bent out of plane as the rim flexes to the side (middle picture). Pedaling dynamics can also have an effect on this kind of side loading as well, especially during hard efforts either out of saddle or just climbing. The asymmetry of the rear wheel exacerbates this problem because of the unbalanced load on the spokes.

In my (considerable) experience of spoke breakage, if I hear a ping, it will be when the wheel is bent out of plane on a corner or when pedaling. Seldom does a spoke break when just rolling down the road. The front wheel is symmetric (or just slightly asymmetric with discs) so it doesn’t have the same problem.

seypat

Back when I was in grade school sometime between 1973 and 78, I was booking it across a golf course between groups teeing off. One of my brake levers slipped off and went into the front wheel. All of the spokes ripped out of the rim and wrapped around the front hub. The fork/front hub dug into the ground and the bike just stopped. I stepped off like Legalus in one of the LOTR movies. I picked the bike up, then started the 1 or 2 mile walk of shame back to my house.

mprince

Nice ramble but the question was about front spokes...

cyccommute 

Read my post again. It addresses why front spokes don’t break all that often. It also addresses why rear ones do.

tomato coupe

Impacts certainly can break spokes. I've got several friends and some railroad tracks that will attest to that.

cyccommute 

Explain how an impact can break a spoke. There is no solid connection between the spoke and the rim. The rim can slide up and down the spoke which makes transmission of the impact’s force zero to the spoke itself. The rim can be damaged but not the spoke. Railroad tracks are nothing to the rocks, drops, and jumps encountered in mountain biking. I don’t think anyone would argue that mountain bike wheels are more prone to spoke breakage than road bike wheels nor vice versa.

tomato coupe

An impact creates an upward force on the wheel, which increases the tension in the upper spokes.

KerryIrons

Quite simple really. Impact forces cause the spoke to unload and then "snap back" with the snap having a significantly higher force than the equilibrium forces of just riding. If that force is enough to break the spoke, there you have it.

cyccommute 

That’s not enough to make an individual spoke fracture due to the impact. It may cause fatigue over time but as an instantaneous impact, it won’t have enough force to fracture the spoke. The increase in tension is going to be spread over all the spokes of the wheel with the exception of the ones closest to the contact patch. The change in tension will be uneven with higher tension changes nearer the impact that decrease rapidly with the distance of the spoke from the impact. But an individual spoke won’t experience enough of a tension change to cause a fracture.

The same spreading of tension works as the force of the impact lessens but in the opposite direction. The spoke won’t “snap back” with enough force to fracture the head of the spoke. The rest of the wheel spreads that same increase in tension as it did the decrease in the tension. The return of tension has an impact on the fatigue of the spoke over time but it’s not an instantaneous failure.

KerryIrons

It will if the spoke is already fatigued and getting ready to break. Most of the time it won't break the spoke. Once in a while it will.

Flip Flop Rider

yes once. best I can tell it was from running over neighborhood speed bumps to hard or with too much force. The spoke pulled a hole/gash in the rim

This was after several thousand miles of riding, so that's my best guess

cyccommute 

That is not the impact “breaking” the spoke. The spoke was already broken and just waiting for the right time to fail completely. Additionally, since this is a discussion about front wheels, the spokes are far less likely to be fatigued than rear ones.

cyccommute 

That’s not what most people would call a broken spoke. The rim failed but the spoke didn’t. That’s a common wheel failure but not a spoke failure.

tomato coupe

If a spoke is already fatigued, the increased tension from an impact can be enough to break a spoke.

I think everybody else will agree that a spoke "breaks" when it becomes two pieces. But, I guess you're free to make up your definition.