Bicycle Mechanics - Excessive spoke tension - rim damage?

Fellow pedallers,

I just bought my first 'real' road bike - a Felt F75 with Mavic CXP22 rims with eyelets and aluminum nipples. After bringing it home I gave it a close inspection and realized that there were bumps on the inside face of the rim right at the eyelet as if the nipple wanted to pull out. They were most pronounced on the eyelets leading to the spokes connecting to the drive side of the rear rim (whose spokes were quite taught) but I could see smaller humps on the other side of the rim and and even some on the front wheel.

I took it back to the shop and the techs took their meter and measured the drive side spokes as '80' and said it was normal. I was in disbelief. They checked other bikes in the store (the ones with the same rims I presume) and said they looked similar - they had the same bumps in the rim.

I made a stink and their rep is going to check out the issue. I imagine it would be hard for him to admit any issue so Im turning to you guys for help - is there an issue at the factory? Are these rims just not meant to take 'normal' tension and are giving way? am I nuts?

picture?? There are some mavic wheels that come with like ''bumps'' in the rim where the nipples are but just part of the design just like kysriums

I just checked two different model bikes we have in our shop that come stock with CXP-22 rims, and the rims are perfectly smooth between the nipples, no bumps. I've not seen your bike in person, so I won't make a judgement on what's going on with it, but there should be no raised area on the rim around the nipples, it should be smooth.

Btw, if there is a problem with your wheels related to the bumps you describe, it's most likely too much spoke tension and not a defect in the rims themselves. CXP-22's are not high end rims, but they've been around for a long time, are reliable, and are indeed capable of withstanding "normal" spoke tension.

My Mavic CXP-33s show a slight hint of this this at only 110 kgf.

Also Velocity Aeroheads and A23s will do this as well at only 110 kgf.

A very slight bulging effect around the sides of the holes seems to be common with lighter weight rims with aero profiles.

=8-)

My Mavic CXP-33s show a slight hint of this this at only 110 kgf.

Also Velocity Aeroheads and A23s will do this as well at only 110 kgf.

A very slight bulging effect around the sides of the holes seems to be common with lighter weight rims with aero profiles.

=8-)

The OP's rims are CXP-22's, a heavier rim than the CXP-33's.

It'll even show on some DeepV's...not often...and when it does - faintly.

The worst are Star Cricles from China and copies often found on Virtue bikes...

=8-)

The seriousness of the bumps as an indicator of excess tension depends on the wall thickness of the rim along the spoke line, and the ductility of the metal. I ride very light (310gr) tubular rims, and these will begin so distort at the spoke holes at very low tensions, yet because they're fairly ductile they can do this without danger of stress cracking.

Other rims, especially hard anodized rims, and some of higher strength alloys, aren't so ductile and the distortion can be a prelude to future stress cracking. I can't speak for these wheels, not having seen them, and not having enough experience with the particular rims to know how they'll handle the distortion. So this may be a case where only time will tell.

What the OP might seek as a compromise is a warranty against failure by stress crack at the spokes for a mutually agreeable time period. Obviously this won't be a blanket warranty, since wheels can fail for any number of reasons, just a bet that that they won't fail for the one reason stipulated.

As a structural engineer Ive seen steel failures as a result of fatigue and while we dont work with structural aluminum, its properties are not confidence-inspiring. There is less elasticity in aluminum than in steel and when that threshold has been breached (the bulging is a permanent deformation) the material capacity to resist tension is compromised.

Right now I feel like this is a safety risk and cant see myself enjoying riding my new bicycle. Whether a manufacturing defect of the rim or an assembly error I cant swallow this as acceptable.

What were they measuring the tension with? '80' would sounds low for the drive side if that's kgf, but I you could have a heavier straight gage spoke and I don't know what is normal for those.

As a structural engineer Ive seen steel failures as a result of fatigue and while we dont work with structural aluminum, its properties are not confidence-inspiring. There is less elasticity in aluminum than in steel and when that threshold has been breached (the bulging is a permanent deformation) the material capacity to resist tension is compromised.

Right now I feel like this is a safety risk and cant see myself enjoying riding my new bicycle. Whether a manufacturing defect of the rim or an assembly error I cant swallow this as acceptable.

Not a safety risk...

It a a hole cracks...you'll get a slight wobble that drag the brakes...you'll stop...b*&*%, moan, grumble, do a sailor and stuff...

Wonder what their "80" meant...

=8-)

Wonder what their "80" meant...

=8-)

I'd guess it was kgf on the rear drive side with air in the tire, which would probably be about right.

I've seen a little bit of distortion on certain rims like everyone is mentioning, but what makes me think something's off here is that I checked the bikes I mentioned in post #3, and there is absolutely no raised area around the spoke nipples on the pre-built wheels with CXP-22's in our shop. None, completely flat. Which makes sense, because they're heavy rims. I think you'd have to really overtension the spokes to get very noticeable "bumps" around the nipples like the OP is describing on these rims, or maybe have a batch of defective rims, I don't know. But again, there is absolutely no bump around the nipples on the wheels with CXP-22's in our shop.

As a structural engineer Ive seen steel failures as a result of fatigue and while we dont work with structural aluminum, its properties are not confidence-inspiring. There is less elasticity in aluminum than in steel and when that threshold has been breached (the bulging is a permanent deformation) the material capacity to resist tension is compromised.

Right now I feel like this is a safety risk and cant see myself enjoying riding my new bicycle. Whether a manufacturing defect of the rim or an assembly error I cant swallow this as acceptable.

As a structural engineer you also know that fatigue is the result of movement or flex, not static load per se. In use the rim doesn't flex much, so other than this initial set, it shouldn't fatigue any faster than otherwise.

In any case it's certainly not a safety issue, spokes have been breaking for decades and I doubt anyone has ever been injured as a result. There's plenty of redundancy in a wheel so the loss of a single spoke, whether through spoke failure or through a rim failing at the spoke hole won't lead to anything worse than inconvenience. In any, while spokes break without warning, your rim will announce impending failure with visible stress cracks, weeks or months in advance of letting go.

There's not enough info here to know if this is normal build distortion or an indicator of a over-tightened wheel (or too much spoke for the rim) but all of that doesn't matter, even if it isn't a safety issue.

It's a brand new bike, and assuming you haven't ridden it, you don't have to accept delivery of anything that displeases you. if you have ridden it, either reconcile yourself to the "issue" or do your best to negotiate a swap or credit.

One other note: oblique, you've mentioned that there are eyelets on your rims. CXP-22 rims are available with or without eyelets, and the CXP-22's in our shop, on the bikes I've mentioned, don't have eyelets. So there is a difference at the spoke holes between your rims and the rims I looked at. FWIW.

A good, clear pic of the bumps around the spoke holes you're talking about would be helpful.

I'd guess it was kgf on the rear drive side with air in the tire, which would probably be about right.

My drive side tension goes down maybe 5 kgf when I put a tire on starting from 125-130. That's with a 28 spoke rear laced 3x with DT comps. What kind of numbers are you working with? That's a clincher, from what I understand tubulars are affected more.

My drive side tension goes down maybe 5 kgf when I put a tire on starting from 125-130. That's with a 28 spoke rear laced 3x with DT comps. What kind of numbers are you working with? That's a clincher, from what I understand tubulars are affected more.

I usually see about a 15-20% drop in measured spoke tension, I think, when measuring spoke tension with a fully inflated clincher road tire vs. measuring with no tire mounted. Maybe I'm off a bit, but the difference isn't as minor as you say IME. Then again, I don't measure a lot of spoke tensions with inflated tires on the rims, either. :D............But anyway, I don't think it would be too far off to say that if they measured the rear drive side tension with a fully inflated tire and got 80 kgf, the actual tension (without a tire mounted) would be somewhere in the 90-100 kgf range. Which would be a little on the low side but not too far off. Of course, that would be the opposite of what we would expect with the distorted rims.

Again, pics of the rims we're discussing would help-

Whatever the tension drop tire inflation causes is moot. Yes, the tension drops somewhat, but that's factored into the published recommended tension specs. As long as the tension is in the working range (above a minimum level) added tension doesn't make a wheel stiffer or longer lasting. On the contrary, excess tension and/or overly stiff spokes can cause rim stress cracking.

Other than low spoke count wheels, 80kpf or more is well sufficient. The real issue for rear wheels is left side tension which is always much lower. I try to keep that at 60kpf minimum, bringing the right side as high as needed to achieve that.

Whatever the tension drop tire inflation causes is moot. Yes the tension drops somewhat, but that's factored into the recommended published tension specs. As long as the tension is in the working range (above a minimum level) added tension doesn't make a wheel stiffer or longer lasting.

Other than low spoke count wheels, 80kpf or more is well sufficient. The real issue for rear wheels is left side tension which is always much lower. I try to keep that at 60kpf minimum, bringing the right side as high as needed to achieve that.

My head's kind of spinning (no pun intended)...... as often happens we're going into a lot of things that have no bearing on the OP's question . The main questions are whether or not the spokes are over-tensioned to the point that they have damaged these 500+ gram rims, or perhaps the rims are defective, or maybe the OP is simply over-reacting and making much ado about nothing.

A sidebar question was posed "I wonder what the '80' they mentioned is referring to?" I made a guess as to what the '80' referred to. My apologies to the OP for going off topic, hopefully this thread won't get too sidetracked and we can stay focused on the origional question(s).

And to the OP.....pics or it didn't happen. :D

We tried to answer the OPs question, and I for one tried to offer reassurance that it probably wasn't a problem, and for sure wasn't a safety issue. There's insufficient info to offer the OP a better answer because, there were no pictures, and no clarification of whether the 80 was the direct reading on a tension meter (and which brand it was) or a converted actual tension in kpf or whatever.

Then, as so often happens on the forum the thread drifted into tangents.

Again, pics of the rims we're discussing would help-

+100

This entire thread is 100% guessing without pictures of your actual wheel. What may look like a defect to some may not to others.

+100

This entire thread is 100% guessing without pictures of your actual wheel. What may look like a defect to some may not to others.

yes, pictures might help, but we'd still be guessing, and putting our "knowledge" against that of the wheel builders at felt.



....realized that there were bumps on the inside face of the rim right at the eyelet as if the nipple wanted to pull out. They were most pronounced on the eyelets leading to the spokes connecting to the drive side of the rear rim (whose spokes were quite taught) but I could see smaller humps on the other side of the rim and and even some on the front wheel.

I took it back to the shop and the techs took their meter and measured the drive side spokes as '80' and said it was normal. I was in disbelief. They checked other bikes in the store (the ones with the same rims I presume) and said they looked similar - they had the same bumps in the rim.

I made a stink and their rep is going to check out the issue. I imagine it would be hard for him to admit any issue so Im turning to you guys for help - is there an issue at the factory? Are these rims just not meant to take 'normal' tension and are giving way? am I nuts?[/QUOTE]

If I read the OP correctly, both his rims and others on the same model bike in stock had the same distortion, so a rim defect isn't likely. It comes down to two questions.

1- are the folks at felt generally over-tightening their wheels? In which case knowing what the "80" figure given referred to might be a guide.

2- is there a safety issue, in which case the answer is clearly no. The rim may eventually stress crack, but that isn't anything at all likely to cause an accident.

Even with pictures, I wouldn't speculate and accuse both the shop staff and the builders at Felt of total ignorance. To do that I'd need to compare the actual tension to Mavic's guidelines for that rim.

Now the OP has a problem in that he lacks confidence in the wheels, and the integrity of the shop staff, who reassured him that all was OK (which in all likelihood is true). It's up to him to determine the extent of the non confidence. If it's high I suggest he consider returning the (unridden) bike. Not because there's anything actually wrong, but because seeds of doubt usually take root and sprout, and that will color his judgement if and when anything else is wrong, or goes wrong in the near future. I know I couldn't enjoy a bike I didn't have confidence in and I assume the OP is the same.

oblique, If your wheels are showing a pattern similar to this:
236256
then that is a sign of over tensioning. These wheels were way over tensioned, but I didn't know that until I noticed the unusual pattern on the braking surface (Maybe hard to see in the photo, look on the rim where a spoke is.). I don't remember how tight they were, but retensioning made a more uniform pattern. There was no damage to the rim as it's still in use at least 15 years later.

Brad

The marks in that rim are because the rim is not machined to start with. Old rims were not machined and always have those marks in the braking area, doesnt matter if the spokes are over tensioned or not. If the rim is not machine will get like in the picture, spoke tension has nothing to do with it, that rim is simply old and the bike is not like a super bicycle to put it as example either :D

If the rim hole and eyelets gives up then is clear u have over tension, besides that the next thing is that spokes start snapping out of the blue. As for the OPs wheel, well... doesn't surprise me at all and yes sure the spokes were over tensioned. Some iterations of those rims came up better than other batches, that's why doesnt surprise me at all the problem.

I doubt the alloy used in cx22's would deform without cracks showing externally. I replaced some Alex rims with CX22's (no eyelets) on my SS sputnik with high-flange hubs 3-cross. I tensioned them pretty tight (I judge by "pinging", not a tension gauge). They ride very rough compared to the previous setup. I don't notice any bulging.

The obvious answer here is that the OP's rim labels are either
facing the wrong way or applied asymmetrically.

I'm surprised no one has suggested it.http://www.runemasterstudios.com/graemlins/images/spin.gif

The obvious answer here is that the OP's rim labels are either
facing the wrong way or applied asymmetrically.

I'm surprised no one has suggested it.http://www.runemasterstudios.com/graemlins/images/spin.gif

1. Put down the pipe.
2. Hit the back button of your browser...mouse, not your fist.
3. Refresh forum list...that's mouse again, not a stiff drink.
4. Find and click on correct thread...that's mouse again, not the sound stuff...

=8-)

1. Put down the pipe.
2. Hit the back button of your browser...mouse, not your fist.
3. Refresh forum list...that's mouse again, not a stiff drink.
4. Find and click on correct thread...that's mouse again, not the sound stuff...

=8-)

Your suggestions of drug and alcohol use, while correct in principle, are very hurtful.:o

I'm simply trying to make the connection from some valuable information I
picked up elsewhere on the forums.......duh!:p

Your suggestions of drug and alcohol use, while correct in principle, are very hurtful.:o

I'm simply trying to make the connection from some valuable information I
picked up elsewhere on the forums.......duh!:p

Well let's put it this way...

If you can spin a wheel and count the spokes while it's spinning, then you must be Hammie!

http://www.youtube.com/watch?v=a3O2kuEXf8Y

=8-)

:p

Well let's put it this way...

If you can spin a wheel and count the spokes while it's spinning, then you must be Hammie!

http://www.youtube.com/watch?v=a3O2kuEXf8Y



=8-)

:p

This from a guy peddling $7 hubs.. rims for a few bucks more.. and wheelsets for what was it.. cheeep.. with of course NO warranty.

The pied piper of the garage bikes.......... :roflmao2:

THEN.. you need to post an apology here to 3alarmer. Your remarks were.. what.. indicative of your character? or... what are you SMOKIN'?

The marks in that rim are because the rim is not machined to start with. Old rims were not machined and always have those marks in the braking area, doesnt matter if the spokes are over tensioned or not. If the rim is not machine will get like in the picture, spoke tension has nothing to do with it, that rim is simply old and the bike is not like a super bicycle to put it as example either :D


Quite possible. The wheelset was new at the time that patteren showed itself and when I retensioned the set. Other CXP10 and CXP12 wheelsets (I like those rims) never showed that pattern so you can understand my correlation.
236315

Brad

This from a guy peddling $7 hubs.. rims for a few bucks more.. and wheelsets for what was it.. cheeep.. with of course NO warranty.

The pied piper of the garage bikes.......... :roflmao2:

THEN.. you need to post an apology here to 3alarmer. Your remarks were.. what.. indicative of your character? or... what are you SMOKIN'?


You know 3alarmer and I are poking at each other right?


BACK > REFRESH > DOWN > http://www.bikeforums.net/showthread.php/789485-Bought-a-wheel-with-the-sticker-orientation-backwards-what-to-do


=8-)

This from a guy peddling $7 hubs.. rims for a few bucks more.. and wheelsets for what was it.. cheeep.. with of course NO warranty.

The pied piper of the garage bikes.......... :roflmao2:

THEN.. you need to post an apology here to 3alarmer. Your remarks were.. what.. indicative of your character? or... what are you SMOKIN'?

http://www.runemasterstudios.com/graemlins/images/chillpill.gif

No need......we do this late at night here in NorCal when neither of us
can sleep but both ought to be in bed. Age related insomnia, I guess.

http://www.runemasterstudios.com/graemlins/images/poke.gif

Sometimes I call him Mr Bunny, and sometimes he wants to call me Snickerdoodle,
but he is too shy to state publicly how he really feels.:o

I've been saving one emoticon in reserve, which i will trot out
in one of our comic exchanges some time in the future...http://www.runemasterstudios.com/graemlins/images/neener_neener.gif

For the record, Mr Bunny really does know more about this stuff than do I.

It's just that sometimes he can be such an old cranky pants.:D

Other than low spoke count wheels, 80kpf or more is well sufficient. The real issue for rear wheels is left side tension which is always much lower. I try to keep that at 60kpf minimum, bringing the right side as high as needed to achieve that.

I agree that the minimum spoke tension on the non-drive side should be the primary concern. But with modern multi-speed bikes if the NDS tension is 60 (kgf assumed) the DS tension for a typical road rear wheel is going to be a lot higher than 80.

I agree that the minimum spoke tension on the non-drive side should be the primary concern. But with modern multi-speed bikes if the NDS tension is 60 (kgf assumed) the DS tension for a typical road rear wheel is going to be a lot higher than 80.

Absolutely, the 80kpf tension is about the range that ensures that all spokes remain under tension at all times (32 spokes or more). Going higher does not improve the mechanical properties of the wheel and so 80-90 is fine for front wheels. On the rear, there's little choice since, as you point out, RH tension will be considerably higher. I try to find a balance between lower than ideal tension on the left, and excess tension of the right.

While most modern rims will handle tensions of 120kpf or more giving the builder wide latitude, I prefer to use very light rims and am therefore limited by max RH tension and min LH tension into a very narrow range, in some cases having to pinch on both sides.

Supposed to hear back from them tomorrow. Ill take some pics if I have to go over there.

Im wondering what Mavic would say. In my mind the bottom line is that the rims, as they are, dont meet factory specification even if operating them can be warrantied.

We have a bike in our shop right now that's being serviced, a different brand bike than the two models we have on the sales floor with CXP-22's. It's equipped with CXP-22 rims with eyelets. Absolutely no bulging around the eyelets, no bumps, nothing but perfectly smooth. If there's significant bulging around the eyelets on oblique's rims, I'm convinced there's either too much spoke tension or the rims are defective. More likely too much spoke tension IMO.

Supposed to hear back from them tomorrow. Ill take some pics if I have to go over there.

Im wondering what Mavic would say. In my mind the bottom line is that the rims, as they are, dont meet factory specification even if operating them can be warrantied.

So let me see if I understand. You bought your first "real" road bike (your words in the OP), and based on that great depth of experience, you're qualified to judge whether rims meet a factory spec. You can do this without knowing the material the rims are made of, what the factory spec. is, whether they were fine but built over tight, whether they were built overtight in the first place, without knowing the factory's recommended spoke tension, or measuring what the tension actually is.

That's pretty good structural engineering, and I salute you.

On the flip side, there's the expertise of the shop that did measure the tension, the evidence of the other similar wheels showing similar bulging, the quality controls in place at the Mavic, the skill of the wheelbuilders at Felt, and the quality controls at Felt.

While it's possible that the wheels are either over tight, or the rims are soft, the odds favor ductile rims within Mavic's quality spec. built to the high end of the allowable range. Anyone who says otherwise without knowing both the actual tension and Mavic's max. tension spec for these rims is just speculating, or not so politely - blowing smoke.

I repeat my earlier suggestion that you see if you can return the bike based on your concerns. If Felt can't properly build wheels, or spot defective rims in quantity, what else did they get wrong?

In fact the bike is almost assuredly fine, but if you trust a bunch of strangers on a forum, about whose credentials you know absolutely nothing (including mine), more than you trust the bike, then you'll never be happy with it. If the shop is smart they'll recognize the situation and get out of it as soon as possible, and be glad they did.

Sorry for the tone, but sometimes things like this need to be said.

Im here to get a second opinion because I think theres a problem. Theres no way to know for sure where between forging the aluminum and building the wheels this problem arose but at least we can see if there are similar issues out there - surely the 'strangers' on this board can help with determining that. Frankly Im inclined to take what these 'strangers' have to say, albeit with a grain of salt, as more 'expert' than someone whos biased towards running a successful business.

I thank you for your insight but if these rims were designed to bulge then it seem that there is some inconsistency at Mavic's factory.

Im here to get a second opinion because I think there's a problem. There's no way to know for sure where between forging the aluminum and building the wheels this problem arose but at least we can see if there are similar issues out there - surely the 'strangers' on this board can help with determining that. Frankly Im inclined to take what these 'strangers' have to say, albeit with a grain of salt, as more 'expert' than someone whos biased towards running a successful business.

I thank you for your insight but if these rims were designed to bulge then it seem that there is some inconsistency at Mavic's factory.

I understand your concerns, though I believe they're misplaced. But be that as it may, I strongly expect that this will play out such that you'll end up with a choice between accepting the bike and wheels as is, or returning or exchanging it for another bike (not another of the same model since they all seem to be the same), or a refund.

That you don't trust a dealer or manufacturer that you consider biased toward foisting defective goods on you, is why I suggested you return the bike. I'm not the one to argue that the wheel isn't too tight because I'm usually the one who says that the trend has been to wheels that are unnecessarily tight in general. But being tighter than necessary isn't the same as being too tight.

I haven't seen the rims, but asked a few local dealer clients who have these bikes in stock, including one who's one of the top wheel builders in the area, to take a look, and they report the rim distortion as being across the board on those wheels (as did your dealer). The wheel builder also checked the tension of his dimpled Felt wheels and reported it wasn't unusually high.

If you reread my first post you'll see that I said such distortion was common with ductile rims (extruded, not forged) were built tight. Looking at the rim's profile, I note that the hole and eyelet are radial. I can imagine that the pull angle of the spoke would cam the nipple and eyelet pulling out a bulge on the tight side until it settled in alignment to the spoke. This is less likely to happen with a non-eyelet rim because the nipple is freer to float to alignment.

I'm not invested in your bike, the dealer, Felt or Mavic, I'm simply trying to give you some measure of reassurance that this isn't rare or unheard of, or in any way hazardous. Worst case is that you'll eventually see some stress cracking, and ultimately (if ever) a spoke pulling through. But that's the worst case, and won't necessarily happen which is why I suggested that if you otherwise like the bike, you ask for a limited warranty covering replacement wheels if the rims stress crack within 2 years or so.

But, ultimately, the issue isn't the wheels but your confidence and comfort level. You spent a nice chunk of change and should be able to ride the bike with confidence. Regardless of the actual structural soundness, if you don't trust it or the dealer you should look elsewhere.