atmdad

Curious as to what would cause a spoke to break while riding. I was out for a ride Saturday afternoon and "popped" a spoke. The bike/wheel is relatively new, just over 900 miles on it. The roads I ride are generally pretty good and I hadn't hit a pothole or anything prior. I always try to keep about 100 psi in the tire and this time was no exception. I will have to double check but i'm pretty sure the spoke was laced to the drive side of the hub.

I was heading to my office and was closer to it than home so I continued on and wound up going another 20 miles like that. Paranoid the entire wheel was going to explode and the CF frame would then spontaneously combust I would have to be scraped up off the road somewhere.

operator

- Poor fit between spoke head and hub
- incorrect tension
- large variation in tension
- loaded bike weight exceeding wheel component quality
- wheel not stress relieved
- crappy spokes

A brand new bike with OEM wheels probably all of the above.

atmdad

Yea, figured it could be a multitude of possibilities.

Wait a second, "- loaded bike weight exceeding wheel component quality", did you just call me FAT?

It's just a puffy shirt, I swear.

coasting 

i had a spoke break on an old wheel and after the first spoke went, the bike shop said i should replace all the spokes. i thought that was such an overkill so i said replace just that one. the mechanic said he would do it but he will see me when the next one breaks and just as he said i was back in a couple of weeks with 2 broken spokes.

lunacycle

Where did the failure occur -- e.g., at the threads, the "J" bend -- or did the spoke nipple itself break?

merlinextraligh

Break one spoke, replace it, check that the wheel is properly tensioned, ride. Sometimes stuff just happens, and you may get thousands of more miles without a problem.

Break a second spoke, and definitely a third, rebuild the wheel.

stien

/\ Or just sell them and buy another set

atmdad

At the threads. Before I left my office to go back home I lopped off the spoke down near the hub so it wouldn't flail around on the ride home and there were no threads on the broken end. I'll look later this evening, but i'm pretty sure when I got home the nipple was gone, it was there when I first looked when it happened.

Anyways I'm dropping it off at the shop in the morning, they offer a free check-over/readjustment whatever for the first year so I might as well take them up on it and have them fix the spoke. I'll definitely ask them to go over both wheels.

GP

What kind of wheel? How many spokes? How much do you weigh?

In my experience its usually a POS OEM wheel or too few spokes for the rider's weight.

Namenda

Have you ever had to true the wheel? I broke a rear drive-side spoke recently, just after having my lbs true the wheel for me. Broke at the threads. They had trouble truing it, as it has straight-pull spokes, and the spoke was spinning in the hub while they were turning the nipple. They took a pair of pliers to hold the spoke, and got the wheel trued. Guess which one broke?

I replaced the spoke myself, and got it trued. Working like a charm, so far (knock wood).

atmdad

I bought the bike new in April, '10 Giant Defy Advanced

Wheel is Mavic CXP22, Forumla Sealed Hub, 28 spokes, Sapim Race 14/15g spokes. Lately i've been bouncing around between 185 - 190 lbs, depending one how much beer I consume over the weekend.

I just went over 900 miles on this when the spoke popped Saturday, and all i've done with the bike is keep the tires pumped up, minor adjustment to front derailer and occasionally wipe down the road grime. So it can probably use a basic check-up to adjust for cable strech etc. but I just haven't done it. I'm sure the LBS just made sure the wheels spun true and didn't completely check the tension on every spoke before they assembled the bike.

GP

Sounds like a good wheel and I don't think 190 is too heavy for 28 spokes.

BarryJo

Popped a spoke on tonight's group ride (rear wheel, the nipple is still intact but I haven't had a chance to inspect the rest of the wheel) - I think I jynxed myself this past Sunday when I was telling someone the Kysrium ES wheel set is bomb proof - 12K miles and both front and back were still true (up until tonight).
Popped the spoke on an uphill sprint, still trying to figure out what went wrong.

The most frustrating part was having one of my stronger rides of the summer when this happened, totally pissed me off when it happened and missed the last 20 miles while I limped back to the shop.
Any ideas what might've gone wrong? (I'm 165 so I don't think weight was the issue).
Any other wheel I'd just pass it off as $hit luck.

atmdad

Broke a spoke on the front wheel about a month ago. Not even sure when just noticed it broken before I ride one day. Popped another on the rear two weeks ago. Talked with the shop owner and he said he would talk Giant Rep about it. Last weekend I went into to the shop to get some parts for another bike I am working on and to inquire if he followed up on the wheels. As I was there Fed-Ex delivery comes in, owner looks it over and says looks like your new wheels just came before I even had a chance to ask him about it. Needless to say I was pretty stoked.

BarryJo

^^^^
What wheel?
This isn't supposed to happen with the Kysrium ES, SL or even Elites.

BarryJo

Time to upgrade to Edge Composites, or 404s?
I think so.
The wife disagrees even though I told her the wheel was trashed

carpediemracing 

Any metal under tension stretches a bit. It also gets stress cycled (not sure of term), where it gets loaded and unloaded. Eventually the metal's elasticity drops until it yields/breaks.

For example, airplanes that fly high enough to need pressurized cabins can only pressurize and depressurize x amount of times (100k?). The incident where it looked like someone opened the top of the plane (Hawaii area airline) happened because the plane had 8 take offs and landings a day, traveling between the islands. I think it was stressed like 200k times, and the fuselage finally gave out, literally just split open. Luckily the plane held together (one flight attendant was swept out - everyone else was buckled in) and it landed safely.

(I learned this while watching a show that was called something like "World's Greatest Air Disasters" while on a plane flying cross country - I recommend not watching shows like that while on a plane. You better believe I made sure I had my seat belt on securely.)

There are two ways to deal with metal losing their elasticity.

Prevention - the best way to slow down this tendency is to use more metal. Problem is that it makes for heavier things. You should also use an elastic material. Don't make rubber bands out of hard plastic or Styrofoam - not elastic enough.

Replacement - replace the metal when it gets close to the end of its life cycle.

Finally, if the metal has any imperfections in it, it can break prematurely.

btw if it has aluminum spokes, that's not really an elastic material. As some would point out, you don't see aluminum springs do you? But you see steel, titanium, and carbon springs.

Ultimately, ridden long enough, a wheel will break a spoke. Even if it's a 48 spoke BMX wheel ridden by a 75 lbs kid. Guaranteed.

cdr

BarryJo

Thanks CDR, reading through your post depresses me, I'm wondering if the rest of the spokes are stressed as well and another broke spoke is inevitable.
At least last night I was able to hobble back to the shop.
It wouldnt have been so much fun 30 miles into a solo ride.

Oh well, I'll take the wheel to the shop and have them replace the spoke - hopefully the wheel will hold out for another 10K miles.

DScott

Good result!

If your shop owner is up to it, might be worthwhile to re-tension the spokes on the new wheels. Basically, loosen them all up and re-true the wheels. Takes time (and money), but it seems to help take the gremlins out of machine built wheels.

Cromulent

I once broke a spoke by putting my foot into the front wheel. I thought I was clipped in, but I wasn’t. My foot slipped forward and bounced off the spokes. One snapped. The sound still haunts me.

carpediemracing 

Broken spoke race. A front spoke went in my 16H DV46. Raced the rest of the race on a 15 spoke DV46. At 1:14 the background music fades and POP...

Still did 40? minutes of descents, tucked to move up, and contested the sprint.

Relaced the wheel with all new spokes. Raced it until the end of last year. The wheel is under one of my teammates now. I bought spokes for the rear but a spoke has yet to go.


Blur on screen is cracked protective lens from the 2006 Nutmeg State Games (hadn't realized it was cracked until I transferred both tapes to computer). Not wide angle lens so you can't see much. And this is my pre-HD setup.

I broke a spoke in the rear of my DV46s. Relaced the whole wheel. Have the spokes for the front but none ever popped. Another teammate has those wheels.

cdr