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Broken Spokes(6 posts)

Broken Spokespawistik
May 27, 2003 8:59 PM
Why is it that I seem to break spokes? I don't bunny hop much, just the occasional jump off of a curb. I found I've been doing this recently with both my mtn bike & cyclocross bike. Is it that I'm a bit heavy at 205+ lbs, or is it poor riding technique (hitting those occasional potholes), or is it because certain spokes are excessively tight (probably as a result of having to true the wheel)? Are some spokes better than others (i.e. can I buy stronger ones at a reasonable price)? If it makes a difference, my cx bike has 700C (622mm x 15mm) 32 hole Alex DV15 rims.

Thanks in advance for the insight,
need more info...Steve_O
May 28, 2003 5:39 AM
I'd try this question on the wheel building board on MTBr.

You'll probably need to supply more info in order to get responses though. What kind of wheels are you riding now? How many miles are on them? Did you build them? Do you true them? Where are the spokes breaking?

I went though this several years ago and it led to me buying a truing stand and learning to build my own wheels. Now I decide the specs of the wheels I ride...
thoughts from a 230 lb spokebreakeratpjunkie
May 28, 2003 1:04 PM
a) are your spokes anodized? I've found plain spokes to be stronger
b) Are they breaking at the bend, near the hub? TAke a dremel and de burr the spoke hole. I've found burrs causing some breakage
c) are you using heavy spokes? Staright 14's or 14-15-14, no lightweight stuff for you

as a larger /power rider I've found, we through excessive force expose flaws easier than lighter riders. any slight flaw will be multiplied by the increase in torque at the hub. Are you breaking them when accelerating for a climb or out of a corner? If so this would verify my clydesdale diagnosis.
we'll need more info for a more accurate diag. so let us know where and when you are breaking them. I found I had a whole 'weak' set of DT's (from anodizing) as I broke almost every drive side spoke and a couple non-drive spokes one at a time.
thoughts from a 230 lb spokebreakerpawistik
May 28, 2003 1:40 PM
Thanks for those comments. I'm not sure what spokes are on my wheels, but I assume it's nothing too fancy. When I was at the LBS the other day and asked about stronger spokes, they mentioned DT (not sure what that is) but said I should just stick with the "regular" ones and sold me some for 60 cents apiece. OK, that's pretty darned vague.

I crashed a couple weeks ago when I was going fast around a corner on the road & hit some sand/gravel on the street. I noticed only later that my spoke was broken (at the hub, on the left or non-drive side). I assumed it was related to the crash, but that's not necessarily true, especially since the bike came out far better than I did. The rear wheel however did need truing so it obviously took some degree of a hit. A few days later, another broken spoke (again at the hub, not sure if it was the same spoke or another one). This time I have no event to link it with.

How common is it to break a spoke? Should I expect one every couple of weeks if I'm putting quite a few miles on? I'm putting on 125+ miles on the road/week & 10-30 miles of singletrack trail riding/week.

I'll check for burs on the hub & I'll talk to my LBS & try to figure out what spokes are on there, ensuring that those that break get replaced with a heavy spoke.

DT etc...atpjunkie
May 29, 2003 6:04 PM
DT is a mfr (a good one, Swiss) of spokes and such. Get straight 14 gauge for the strength. Spoke could have broke in crash, wheel went out of true because you lost the tension from that spoke, doesn't mean you 'hit' anything. Mark new spokes with a paint pen, see if it's the same when they break. As they break when you replace check for burrs at the hub juncture. Feel with your fingers for any rough edge and sand or dremel. Spoke is weakest at bend, you just may over torque it. You shouldn't break one a week. Spoke breakage should be rare. I was busting them every other ride, how we figured they were a bad batch. wasn't a repeat of same spoke and new ones are all doing well. At some point have a good wheelbuilder rebuild it 3 cross with straight 14's. What lacing pattern are you running?
need more roadie
Jun 15, 2003 9:56 PM
Spokes break from being to LOOSE, not from being to TIGHT. The rim flattens out a bit where it contacts the road, and a tight spoke gives up a bight of its stretch but stays tight. A loose spoke will instead rattle around momentarly, then snap back to full tension. This results in rapid fatigue and breakage.

Spokes on the NDS rear are naturally the least tight, and any landings from curb-hopping schenagains (yeah, I do them to) will result in larger rim deflections, and thus require HIGHER tension to resist.

Another thing to watchfor is that newly installed spokes MUST be propperly seated into thier postion and stress releived. That means forcefully bedding the spoke head into the hub hole, bending the spoke slightly so it conforms to the line its placed in, tensioning it up, and then overloading that tension slightly in order to remove any previous "shape memory" and help prevent fatigue cycling during moments when the tension is reduced. If these steps are neglected during a wheel build, it won;t stay true well and spokes will snap after a fairly short riding period. Replacing just broken spokes and neglecting this process will similarly cause the same spoke to snap again later.

I've never noticed that "burrs" matter at all. Aluiminum is softer than steel, and a properly tensioned and seated spoke smashes the hub hole down into the shape it needs- not the other way around!
I've got a singlespeed MTB wheel with NASTY chain damage to the spokes right down near the heads, and so far its had zero problems. If there's no signifigant fatigue cycling, potential crack intation sights aren' so big an issue anyhow.