SS 14g 36er Spokes breaking

hey man, i did some searching:

I’m not sure if those are the right ones or not. Also, i saw a pack on ebay for like $9.99 – that might work too.

-corbin

I ordered from Bike Tools Etc. (see my previous post for link). They arrived fine, but I haven’t used them yet.

Thank you for that advice. I asked for them at my local bike store, but they don’t seem to use them.

Me neither!

I wanted my wheel built properly so I took a spoke down to a local engineering place and bought some stainless steel M3 washers. They are not quite as small as the brass ones but they seem to do the job, and are widely available I imagine. Would there be any reason why brass ones are better for wheelbuilding? I haven’t snapped any more spokes yet…

Brass will deform and help distribute the stress at the spoke head better.

The problem with short spokes it that it means fewer threads are engaged in the nipple. This should cause failure at the nipples, not at the hub.

Breakage at the elbows is typically caused by the constant loading and unloading of the spokes as the wheel rotates. A soft wheelbuild can be one cause. The other cause I can think of is if the holes in the hub are drilled too large. 14 guage spokes are 2mm in diameter and should have a hole no larger than 2.3 mm. The brass washers do help with this by tightening up the interface. Brass is better than steel for the washers because brass is soft and will deform to evenly distribute the load.

I’m guessing you can only get straight gauge spokes in coker sizes? Double or Triple butted spokes would possibly help, but I wouldn’t be suprised if you told me availablility was an issue.

The last wheel build I built all by myself (ie: horrible build!) was on the schlumpf, and it I didn’t used the washers. I ended up breaking a lot of spokes! A proper wheel build with washers and proper tension prevented me from breaking any more spokes.

just my 2 cents from my experience.

corbin

I just broke my first spoke on a 36er! It was on my geared 36 and it happened while I was practicing braking. I was going at about 14 mph then did a fast stop with the brake/leaning back and I heard a SNAP. Luckily I ordered 7 extra custom cut spokes from UDC last year, so I just had to take it to my LBS for a quick spoke replacement and trueing.

They said that braking the way I described probably puts a lot of torque on the wheel. I never had any issues with spokes braking till now, and I also never used a brake on a 36er till using my geared 36. I probably had about 740 miles on the wheel before braking a spoke, so that isn’t too bad, and I never maintained the wheel or tightened/trued it.

Weak Nipples!

I have a 2008 KH 29" and have been having problems with the nipples breaking off. I got tired of it and took advantage of my free time this holiday to rebuild the wheel with new spokes. It was my first wheel, and it went well but it took much longer than it would if I knew what I was doing. In any case the wheel feels very solid and the spoke tension is in a reasonable range.

The wheel was one of the old ones built with 13 G spokes, and I replaced them with 14 G spokes as recommended by Bryce:

I looked at the old spokes and nipples, and it looks like the original assembly was harsh. Here is a picture of two of the nipples I pulled out of the wheel. The back one just has the head stripped, but the forward one has half the nipple head ripped out! I assume that these were assembled by machine. Is it common for machine-built wheels to have damaged nipples? It make sense why I kept having them fail, and it gives me hope that the new wheel will be much stronger.

Scott

Nipples.jpg

There is a bit that you can get for a drill that has a screwdriver with a pin in the center. The idea is that you can quickly get all of the spokes to the same “tension” by running the drill until the spoke pushes the little pin and the screwdriver out of the slot. You do it for every spoke and it speeds up the build considerably. The downside is that when the screwdriver starts to wear a little it has a tendency to skate over the surface of the nipple, and sometimes tears it out. This is what your photo’s look like to me. It’s not really a strength issue though. As long as the spokes are long enough to have the end reach the bottom of the slot under tension you have a strong connection at the nipple.

The downside is that you can’t easily use a screwdriver to detension a wheel. The upside is that you lose weight at the rim.

Hi Jtrops,

The breaks I found had the nipple head ripped off, and the spoke still threaded in the remains of the nipple. The spoke did not pull out of the nipple.

Scott

I think you are correct that the damage you show in the picture was causing the problems you were having. On the lower nipple pictured about 1/3rd of the surface which resists the spoke ‘pulling through’ the eyelet is missing. The deformation of the material will also cause ‘stress risers’ further increasing the chance of failure. You could have probably have fixed the wheel by just replacing the affected nipples, but that is easy to say with hindsight. :slight_smile:

One noob error with wheelbuilding is not to have the spokes pull the rim weld together (the spokes straddling the weld should be as angled over it as possible). Another is not to stress the spokes as you build it to bed them in (gently ‘walk’ on the wheel as you build it, and then over tension it, before slackening it back to the correct tension). Also, check the tension after the next 3 or 4 rides as it settles in.

Good luck with your new wheel!

Not sure why you think this is an error. Most wheel builders shoot for the opposite – you want the spokes nearest the valve hole to be parallel for easy access to the valve. For a 36-spoke wheel, this causes the spokes at the seam to be “angled”, but for a 32-spoke wheel they would be parallel. There is not going to be any significant difference in the force across the seam anyway – the rim is under significant compression, including at this joint. In the 32 years I’ve been building wheels, I’ve NEVER seen nor heard of a rim failure precipitated by the rim pulling apart at the seam. It can’t happen. Most rims aren’t even welded, but loosely pinned.

The overload stressing of the spokes that you mention is absolutely critical to the wheel, and it will be completely invisible if not done correctly. It is also equally important to correct the spoke line by bending the spokes to conform to the hub and the nipple. The object of both is to momentarily overload the spokes so that they plastically deform permanently into the shape that they are held at by the wheel. After this occurs, during normal use the metal doesn’t fatigue. If this isn’t done properly, then the spokes fatigue during normal use and eventual breakage is guaranteed.

If the wheel is properly stressed and tensioned during the build, no settling of the tension will occur in subsequent rides.

The ‘angled spoke at the weld’ tip was told to me when I built my first wheels about 20 years ago and I have passed it on unquestioningly and unquestioned in all that time in good faith. However, in that time I have built maybe a dozen wheels or so, so I am prepared to stand corrected :o

I agree with your point about getting the spoke to sit in the rim hole correctly reduces fatigue. Maybe I’ll pass that on in future instead :slight_smile:

I started with a fully assembled wheel, so I replaced the spokes one at a time and ended up with the same pattern. (Why make it hard?) I did “stress relieve” the spokes and adjust the tension using a tensiometer. It runs true. I did not do anything special at the end of the spoke that goes into the nipple. I will look at the wheel and see if it is a problem.

Thank you for the advice. :slight_smile:

Scott