The rear wheels on my commuter bikes go through broken spoke phases, and I just went through one recently on my summer commuter bike. I can attribute that phase mostly due to the commute route that I was taking since I was riding off a tall curb in one spot, and I was riding with heavily loaded panniers.

Since my time is relatively cheap, spokes are inexpensive, and my commutes are not what I consider very long, I just replace them as needed.

Don't press you luck, guys. Let's lose some weight so our spokes don't outlive us by too much. I'm trying, too.

I've been trying for 18 months and 4,000 miles. Sad thing is, I have already lost some weight during that time to get to where I am. Here's to keeping that up and lending my spokes a hand, though...

I weigh 195 lbs (down from 215!), around the same as you. I'm guessing it is your wheels. I put my wheels through hell, riding relatively quickly on a lot of very sub-par road conditions (potholes with their own zipcodes). I've never broken a spoke (although I have bent some rims. Maybe get a better wheelset?

Nope.

Spokes fail due to fatigue, with the number of cycles dependent on average stress and magnitude of the stress cycles.

Not all of the spoke elbow was taken past its elastic limit when the spoke was made, so areas of high average stress remain in wheels that are not stress relieved.

With these areas having about the same stress in all the spokes, those with the same tension on top of that which undergo the same stress cycles (about 750 a mile with a tension change of 40-60% of bike+rider weight) should fail about the same time.

I go through stages where I break a lot of spokes on the rear wheel, 32 spoke, 26" rim.
My mtn bike has rim brakes, so one theory is when the rim metal thickness is reduced to a certain point, the wheel starts to go out of true more often, then some spokes have too little tension, others perhaps too much.
Recently, I got a Park spoke tension meter, and I now regularly check each spoke for tension every 6 weeks, some do need to be adjusted, the tension can change over time. It seems too little tension causes the most breakage.
I'm not so heavy <160, but the bike carries a lot; 50-65 lbs total for commuting.
My rims seem to last 2 years on average (12K to 15K miles), these are a store bought wheels, not hand made. Hand made 36 spoke will be my next experiment.

Drew Eckhardt, I think I understand and agree with what you're saying, but it seems a little garbled. Can you re-read your post and clarify a little?
buzzbee, you are correct about too little tension. Though it is counter-intuitive to the lay-person, proper (high) tension ensures that the cyclic stress that the spoke is exposed to is minmal, so accumulation of fatigue damage is eliminated. Low tension results in high cyclic stress, so fatigue damage, leading to failure, is accelerated.

I'm not sure that this is a very effective way of handling it. It would be a lot more efficient to just replace all of them at once. Clearly if you have 5 or 6 broken spokes, the rest of them are probably fatigued as well. Replacing all of them guarantees a fresh start for the wheel.

Four years ago, I was in this exact predicament with a cheapo replacement wheel. I went out and bought 36 straight gauge DT spokes and rebuild the wheel. I'm still riding on it 4 years later. No more broken spokes.

I'll start checking into some better spokes, but having an occasional broke spoke forced me to regularly check my wheel for being true.

Yes, and no - spokes often (but not always) fail due to fatigue, but the number of cycles depends on how many wheel revolutions have occurred, not on anything to do with average stresses and magnitudes. How much damage is done by fatigue (and, in steel, whether any damage is done at all by fatigue) do depend on the magnitude of the stresses and the difference between the high and low points of the stress cycle, but these are separate from the number of cycles.

Huh? None of the stresses in the spoke wheb it's formed are relieved - you'd end up with a spoke that wouldn't hold its shape because it lacked the work hardening that's required near the nipple. Annealed spokes would be unsuitable for use, and couldn't be built into long-lasting wheels because they'd deform too easily. This applies equally at the head, the elbow, and the threads.

The tension change is far, far less than this in a properly-tensioned wheel. The load of the bike and rider is shared by all of the spokes, not just by those going straight up to the zenith of the rim, or even just by those in the top half of the wheel. My recollection, from having done quite a bit of wheel analysis back in college (years and years ago, so I'm going on fuzzy memories here) is that the highest tension is in the spokes facing forward and backward, as they keep the rim from deforming into an egg shape when the wheel is loaded.

Don't forget, a bicycle wheel is highly statically indeterminate, and operates in a highly dynamic environment. Simplifying assumptions must be made with great care. :)

EKW -- good luck! I've lost some ground then plateaued myself, shaking up the diet and off-the-bike exercise program.

Drew Eckhardt & Tundra Man -- I think you're both right. The one (or several) broken spoke(s) creates an extra stress on other spokes that spikes their fatiguing and/or is often enough to push the accumulated fatigue over the top. Peak & cumulative combine.

All -- since we're drifting into all this spoke-ology / metallurgy talk again, let me ask a question that I've heard kicked around but I don't know what the gospel is: for a heavier person, interested primarily in durability (not racing performance, pinching a penny, etc.), which is best -- single-butted or double-butted spokes? There are confounding issues with regard to strength, tension, elasticity, etc. What nets out best?

I weigh 190 and have been riding two different wheel sets over a 2 year span. Haven't had one broken spoke ever.

I assume it's the wheels on the Soho that aren't as great as a wheel can be. What brand and type rims are on the Soho? How many spokes?

Straight gauge spokes all around carry my 330 lbs with no problems whatsoever. No need for complicating things, all that you need is quality workmanship when building wheels, as I already said.

Don't give up! Last year I broke seven spokes on my rear wheel. I ended up replacing 15 spokes (I replaced any spokes that looked iffy) and the wheel is fine now.