Hello all.

My wheels, I know, are toast. But as they weren't exactly cheap, I'd like to know how and why so it doesn't happen again. Care to help me with a post-mortem?

I've got these wheels, had for a couple of years, but don't ride them much because I consider them special event wheels. They have maybe 1500 miles on them. The wheels are 32 hole, double-butted spokes on a 3x pattern. As I was giving them a good cleaning last week to get ready for the new season, I found a number of cracks, both hairline and better around the outside of the rim. All of these photos are of different cracks, and there are more, but I figure you'll get the idea. These are all drive side.

Many thanks. . .

cheap rim with too high tire pressure

cheap rim with too high tire pressure

Too high pressure? Uhm, no.

OP, what rims are they?

Sorry, should have included that. Velocity Aerohead. Sticker doesn't say OC, but it certainly is.

Also, never more than 120psi, just to put peabody to bed.

Kind of indicative of older Velocity rims. They aren't eyeletted, so the nipples tended to pull through.
Could be too much tension on the spokes or just an old rim...

What's the tension on the spokes? Probably too high if these cracked just sitting around.

Also, the Aeroheads are easy to build backwards. The spokes should go to the hub flange opposite the spoke hole on the outside of the rim. that is, the spoke hole is "aimed" through the rim.

THose cracks up high, are usually indicative of high spoke tension. I have seen Velocity replace the rims with those cracks, but not ones with the nipple pulled through.

Sorry, should have included that. Velocity Aerohead. Sticker doesn't say OC, but it certainly is.

Well, now I've heard of an un-eyeleted Velocity rim that has cracked. 1500 miles? That is not very many... how old is it?

BTW eyelets are certainly not something that prevents cracking... even double eyelets.

Those cracks aroudn the nipples look a lot like the ones I've got on my rims. My wheel was also 32 hole 3/2 pattern....all the cracks were driveside. Pretty spooky to find them. But, my wheels had close to 8K on them.

I'd be pretty interested in learning about the failure mode as well. Too high a spoke tension I don't buy.....wiht my wiehgt, the wheel would not have lasted the 1500 miles the OP is talking about.

Those cracks aroudn the nipples look a lot like the ones I've got on my rims. My wheel was also 32 hole 3/2 pattern....all the cracks were driveside. Pretty spooky to find them. But, my wheels had close to 8K on them.

I'd be pretty interested in learning about the failure mode as well. Too high a spoke tension I don't buy.....wiht my wiehgt, the wheel would not have lasted the 1500 miles the OP is talking about.
Then the cracks indicate that the rim and drilling was not adequate for your weight. More spokes, longerlife. Less rider weight, longer life. Next time be more truthful with yourself when making a wheel build combination decision.

um, not always the case. i had 32h training wheels crack at the nipples. soaking wet and bloated i weigh 155 in the off season. i never jump curbs, etc. sometimes parts fail because they are defective...my failure was a combination of mediocre build and defective rim...but i guess i should lay off of the beer and cupcakes too :rolleyes:

unless val is quite large, 32 3x pattern would be more than enough for a "special event" wheel...

I have seen every offset rim fail in the exact same way, Bontrager, Crostini's and aerohead rims. It may have been to high of spoke tension but it was most likely just bad rim. It seems to be a design flaw with offset rims. The drive side spoke holes are drilled straight up and the spokes need to be angled so after a while the force of the nipple trying to angle itself eventually cause a crack right around the centerline of the rim.

The offset drilling itself makes sense, as it does impact the angle that the nipple contact force pulls on the rim. I truly don't think spoke tension was an issue, as the wheels were built by a very reputable builder often referred to on this site.

The offset drilling itself makes sense, as it does impact the angle that the nipple contact force pulls on the rim. I truly don't think spoke tension was an issue, as the wheels were built by a very reputable builder often referred to on this site.

It's likely a combination of both factors. The design may in fact lead to premature failure because of load distribution around the NDS spoke holes, but the tension on the spokes certainly accelerates the process. Oy, but then you can't exactly build 'em without tension, can ya?

FWIW, I had an offset rear that did the very same thing. I had cracks--some very long--emanating from every spoke hole on the NDS side. The wheel builder very kindly relaced the rear with a new, non-offset rim, and even relaced the front to a new rim so that I'd have a matching set.

Everyone,

Thanks so much for your replies. There's a lot to think about here. The consensus seems to be that the offset rim is to blame, and that's particularly convincing coming from Ligero. But there must be a lot of offset rims out there that have lasted longer than this. And does that also explain the spoke pull-through?

John, you've creeped me out. You're exactly right. It was built on the recommendations of a well-known, RBR-beloved wheelbuilder. (I see no need to name names at this point). So, curlybike, you know, eat me.

Still, how did you know?

am, thanks for sticking up for my trim figure.

To those still curious about tension, some picks. I don't know enough yet to know what the numbers really mean, so perhaps an expert could weigh in?

To those still curious about tension, some picks. I don't know enough yet to know what the numbers really mean, so perhaps an expert could weigh in?

According to those readings your tension is between 99 and 110kgf which is just right.

Everyone,

Thanks so much for your replies. There's a lot to think about here. The consensus seems to be that the offset rim is to blame, and that's particularly convincing coming from Ligero. But there must be a lot of offset rims out there that have lasted longer than this. And does that also explain the spoke pull-through?

John, you've creeped me out. You're exactly right. It was built on the recommendations of a well-known, RBR-beloved wheelbuilder. (I see no need to name names at this point). So, curlybike, you know, eat me.

Still, how did you know?

am, thanks for sticking up for my trim figure.

To those still curious about tension, some picks. I don't know enough yet to know what the numbers really mean, so perhaps an expert could weigh in?
With respect to the eating, no thanks, not my flavor. With respect to the tension readings, did you take the readings on the spokes after the rim had cracked? If so, the readings do not reflect the tension prior to the cracking, which would have been higher. Based upon Ligeros statement, that the current readings are just right, then one would think that the tension was, in fact, too high prior to the cracking.
Poor logic? I don't think so, but if you think so, explain why, using sound reasoning other than a respected builder built it. Superior beings foul up every now and then, although seldom.

With respect to the eating, no thanks, not my flavor. With respect to the tension readings, did you take the readings on the spokes after the rim had cracked? If so, the readings do not reflect the tension prior to the cracking, which would have been higher. Based upon Ligeros statement, that the current readings are just right, then one would think that the tension was, in fact, too high prior to the cracking.
Poor logic? I don't think so, but if you think so, explain why, using sound reasoning other than a respected builder built it. Superior beings foul up every now and then, although seldom.The tension on the spoke won't decrease significantly just because the rim is cracked. Up to the point that the spoke is under not tension at all, the reduction on tension corresponds to the width of the crack. In most of the pictures, the cracks are still hairlines. Sound enough reasoning?

The tension on the spoke won't decrease significantly just because the rim is cracked. Up to the point that the spoke is under not tension at all, the reduction on tension corresponds to the width of the crack. In most of the pictures, the cracks are still hairlines. Sound enough reasoning?
No because I have checked the tension, using a tensiometer, in a wheel with a cracked rim, and the change is greater than you allude to. The more cracks the greater the change.

Maybe your wheel was under-tensioned to begin with :ciappa:

I'm just looking at the width of those cracks compared to the thread pitch on a spoke, and it does not seem like most of those those cracks would amount to much change in tension (the first rim being the exception). Of course, many small cracks would rack up a larger change in the rim's ERD and thus a larger loss of tension.

What I want to know is whether the wheel was out of true. It does not sound like this lead to the discovery of the rim failure, but it also does not sound like the wheel had been ridden recently.

Maybe your wheel was under-tensioned to begin with :ciappa:

I'm just looking at the width of those cracks compared to the thread pitch on a spoke, and it does not seem like most of those those cracks would amount to much change in tension (the first rim being the exception). Of course, many small cracks would rack up a larger change in the rim's ERD and thus a larger loss of tension.

What I want to know is whether the wheel was out of true. It does not sound like this lead to the discovery of the rim failure, but it also does not sound like the wheel had been ridden recently.
Dang, I wish they had that gif that you used available in the selection below.
I know exactly what the tension was on the cracked wheel that I checked, prior to the cracking. It was not on the low side for sure, and yes, the cracks did cause a change in the true of the wheel. I can not attest to anything about the wheel in the Original Post

Dang, I wish they had that gif that you used available in the selection below.Just type "ciappa" with ":" on each side.

Just type "ciappa" with ":" on each side.
thanks, but I stole it out of your post.

I'm just looking at the width of those cracks compared to the thread pitch on a spoke, and it does not seem like most of those those cracks would amount to much change in tension (the first rim being the exception). Of course, many small cracks would rack up a larger change in the rim's ERD and thus a larger loss of tension.

First, I think it is very hard to tell from a couple of overly dark pictures how much the entire rim has deformed due to the cracks. Since the cracks are going sideways, you have virtually no information about how much deflection there is along the pulling axis of the spoke. If the movement was the equivalent of one turn of the spoke (one thread) that would drop the tension significantly, especially if there were numerous spokes involved. Finally, you will get spoke breakage from insufficient tension, but it is real hard to ascribe that kind of rim failure to anything but excessive spoke tension (for that rim).

. . .it is real hard to ascribe that kind of rim failure to anything but excessive spoke tension (for that rim).I think everyone agrees that the failure was caused by excessive spoke tension for that rim. Whether the tension was above spec or the rim was faulty or inadequately designed to withstand proper spoke tension is the question.

My comments were based on my interpretation of the pictures, in which most of the cracks appear to be mere hairlines -- much less than the pitch of a spoke's threads.

I think everyone agrees that the failure was caused by excessive spoke tension for that rim. Whether the tension was above spec or the rim was faulty or inadequately designed to withstand proper spoke tension is the question.


Yes, for me, that's precisely the question. I'm really not looking to cause anyone trouble about this, but I need my next set of wheels to last significantly longer than this set. Also, when I'm dropping the cash on new wheels, am I to shake my fist at Velocity or at the builder?

KI, I'm sorry the photos are dark; if you think different shots would tell you something, I'd be happy to take them.

PBB, the wheel is still remarkably true, less than 1mm out of true. It was similarly true the last time I rode it.

John, I still want to know how you knew the origins of this wheel. . .

Origin of wheels can be determened through my vast powers of telepathy.

Was the rim was inadequate to the tensile forces caused induced by the spokes?

...or....

Was the spoke tension greater than the limit dictated by the rim manufacturer?

This answer is beyond even my capabilities....but.....

Yes KI, even a quarter turn of a nipple has an effect upon spoke tension. I know via measurement with a tensiometer that the spoke tension of my offset rear DS was within tolerances specified....and I never had to re-true the wheel prior to failure.

I still buy into the offset issue brought up by Ligero. With a 4mm offset, the nipple will be
pulled at an angle if the spoke hole is drilled vertically. The non-axial load, especially when the spoke load fluctuates during use, will eventually fatigue the NDS of the rim...as that is the side of the nipple that would be making the contact .....as shown n the OP pics.

Does that make sense??

Does that make sense??

Not really. Velocity rims are not center drilled, they are angled. The NDS spokes will pull at a greater angle in either case. Offset rims have been out for a few years now, and most people have had good experience with them. An OC rim would need to be properly designed to take this higher side load from the spokes, and maybe this hasn't been accounted for. Or maybe the Aerohead OC (which has been reported as low as ~400g at some times) is too thin to take these loads. I haven't seen a rash of people complaining about this issue so I doubt it is common or endemic to offset rims. And if the Aerohead OC can't take 110kg on the DS without failing at 1500 miles then it is junk...

And if the Aerohead OC can't take 110kg on the DS without failing at 1500 miles then it is junk...

I just built up a pair of Aerohead and Aerohead OC wheels about 2 weeks ago, so I'll let you know in about 1200 miles how they're doing.

I build them exactly like the Velocity Helios wheelset on their website, except that I used Dura Ace hubs. Same rims, Sapim CX-Ray spokes w/ Al nipples, 24 radial front, 28 3X rear.

I've just trued them and checked the tension. Everything on the drive side reads between 13 and 14 which should be 105kg - 110kg. I'm going to be pissed if they only last 1500 miles, they were not inexpensive to build up.

I just built up a pair of Aerohead and Aerohead OC wheels about 2 weeks ago, so I'll let you know in about 1200 miles how they're doing. I'm going to be pissed if they only last 1500 miles, they were not inexpensive to build up.

My first Velocity Aerohead OC wheel lasted 10K miles (I over-tightened the spokes and had the kind of failure seen by the OP). I backed off on the tension on the second build, and they now have over 22K miles and still going strong. I weigh 180 lb/82 kg. And before you ask, I don't have a tensiometer so I don't know what the tension was on the first build or is on this one.

I'm going to be pissed if they only last 1500 miles, they were not inexpensive to build up.

I'm sure you're going to be fine. Obviously whatever happened to my wheel is rather exceptional. I'm starting to get the feeling that this is one of those "the world may never know" type things.