Yup! I know, I caught that while I was uploading. Didn't make sure I had all my boxes checked lol. thats what I get for talking on the phone while taking my pictures and not focusing.

David. Its not the chain, its because it is cross chained.

It should be two links longer than the big/big combo. I get a little more slack than that, but not much.

No, probably not. That is a forbidden front-rear combination, i.e. one that is not appropriate to use because of the steep angle of the chain which causes noise and wear. Even that slope of the derailleur is workable, but it doesn't matter, since you really shouldn't use it. The allowed gear combinations will look much better. One doesn't size a chain by looking at the extreme gears, but rather at the middle ones. What is it, small front, large rear should leave the RD pointing straight down? Or is it large front, small rear? I can never remember. Always have to look it up.

sorry to divert your thread Bianchi but I think its relevant and of interest to all to discuss since you have an identical hub to mine. My final thinking is this:

Jude has lots of experience and has built lots of wheels presumably all with this tension, it is reasonable to assume she does this because they dont fail.

My own experience of working as an engineer tells me CKs answer to my question may be a conservative blanket answer. The hub shell stretch issue will vary on spoke count and this was not addressed in their answer.

So, I will assume that 65kgf is a recommended tension for a 32 hole hub, they dont make a 36 so 32 is the worst case for flange stretch (apparently the limiting factor). This is likely a conservative number in itself. With 25% less spokes in my 24 hole hub I can up the tension by 25% without exceeding the recommended flange force. Based on Judes experience I will assume spoke hole robustness is not and never will be limiting.

For further justification, look at it the other way. IF 65kgf is recommended for 24 hole hubs based on flange force as the CK email suggests, then lacing a 32 hole hub to achieve the same flange force results in a spoke tension of 48kgf. That in my opinion is silly low.

Therefore to lace radial on a 24 hole hub using the experience of a builder and the advice from manufacturer with a bit of desyphering, the correct and conservative answer in my mind is...........

90kgf


Looking at it another way.... Bianchi states his weight as approximately 175 - 185# (I think), mine is approx 160# or 86% of Bianchi. 115kgf x 0.86 = 99kgf.......not far off

Seems like my RD doesn't go THAT taut in that gear combo though, maybe my chain is too long?

http://cl.ly/image/2v3k0o0n1J1w/rd-stretch.jpg

Like you I am just imagining what was really meant by the 65 kgf recommendation. Wouldn't it be funny (and isn't it somewhat likely knowing what we do) if the CK guy really meant MINIMUM of 65 kgf, not maximum? That almost makes sense!

I don't dispute your reasoning, but I can't think of any example of spoke tension recommendation that varies with the number of spokes. In my experience the limiting factor is the strength of the spoke hole in the rim, which doesn't change too significantly as the number of spoke holes increases from 20 to 32 or more. So rather than higher spoke counts corresponding to lower spoke tension, what I have seen is that higher spoke number wheels just have a higher total tension o+n them than lower spoke number wheels. Having said that, your analysis is perfectly reasonable. And the good news is that for front wheels 90 kgf is within the recommended range anyway so none of this matters anyway.

Neither can I. Im simply trying to make sense of the manufacturers advice. The limiting factor that he stated was hub flange stretch, and his proposed solution was a larger bearing. He made no comment on the spoke holes holding up and Jude is comfortable with high tension in the spoke holes too.

With radial lace, at a given spoke tension, flange force increases with spoke count which is why I have reasoned as I have.

Spoke holes in rims are a given strength based largely on the thickness of rim material, no spoke count makes them close enough to affect eachother which is why their capacity doesnt change with spoke count

Yeah, that's what I was thinking.

i love the multipage tangents...not

Just looked at some old "data" of mine when I was on a horrible weight weenie jag and switched from the stock rim tape on my Reynolds Alta Race wheels to velo plugs. I had the stock tape at 28 grams and the velo plugs at 7 grams. So for me it was 20, not 30. They work perfectly for me, fwiw. I keep a couple spares in with my tool kit in case I lose one while changing a tire ... but it's never happened.

fify.

NONE of the carbon rims we source for our OE customers or that we are developing for ODM have ANY kind of spoke kgf limit. Their failure points are all well above that of any spoke currently on the market.

If anything that makes me question where AC sources their rims.

Good point. Maybe it is as innocent as another case of overdone CYA. Maybe it is a real issue. Is it possible that the issue is not carbon or construction quality, but rather purposeful design, i.e. they intentionally lighten things up and then have to limit tension?

This has been a great thread, tangents and all. Thank you to all who participated. I have learned a lot and am now motivated to build a set of wheels.

Bianchi, I look forward to your ride report on the Belgiums

Zipps have a tension limit of 100kgf, Enve say 130kgf.

How is it possible then to build a rear wheel?

Maybe these recommendations are more about best build principals as opposed to true failure potentials?

Most manufactures seriously pad their limits in general to cover all the possible STUPID out there. Maybe this is a byproduct of that?

Seriously, none of the rims or hubs we work with have any kind of limit. I'm a bit surprised to see marque brands posting limits of any kind.

Quick question: Do those limits very with yaw angles? And if the user experiences negative drag does it affect spoke tension limits?

Curious mind and all.

This makes me wonder what the tension limits are on my Rolf wheels...

Not sure if serious... but will answer anyway.

DS flange is spaced at 19.5mm which is pretty friggin wide. Couple that with Radial DS spokes, and a fairly short ERD thanks to the depth and it's stiff enough to be passable. You don't have to be at 120kgf to be a wheel.Yes, probably. I'd go so far as to say the ones who DON'T pad their limits are probably operating outside of any kind of end-user arena.What does aerodynamic performance have to do with spoke tension?

I keed, I keed.

I was poking fun at some market speak.

The thing is spokes have an optimal range, too so if the rim design takes them outside of that optimal zone then the build will suffer in terms of durability.

My go to value has been based on CX-Ray and at 120kgf DS tension. The hub will dictate the NDS tension. For the front I work to the same 110~120kgf as I assume both the rim and hub will be unaffected and all I can control are the spokes so I work to their optimal range.

Flawed logic?

But you may be on to something. If they really have a limit of 100kgf and you have them tensioned to 99kgf you could be flirting with a catastrophic failure. Imagine if a wind gust hit at just the right yaw angle on a bladed spoke. The sail effect would bend the spoke and add 2kgf and all your spokes immediately rip out of the rim. And BAM! You're dead.

Seems fine to me. The 'optimal range' though is based on elasticity of the spoke and providing cushion against unloaded spokes from becoming detensioned and seeing higher fatigue cycles and/or loosening over time due to de-tensioning. I believe Zipp accepts some tradeoff in longevity for ultimate race performance though truly knowing how close they are to an actual failure limit is tough, since it is presumed that Sapim's own limits have engineeing tolerance as well.

Esp if you find yourself in the magic 20deg yaw angle (also known as the Bermuda Angle) then you could just plain disappear; One minute your Garmin is generating GPS date and the next it's 40 years later, the start ramp you are rolling off is actually and alien spaceship and now you have to protest your DNF result from 40 years ago hoping to get a DFL so you can upgrade to Cat4.

I think that's a movie with Mick Jagger and Emilio Estevez. They just switched to F1 instead of road racing.

I understand your tolerance stack consideration. It certainly would come into play based on the numbers we're tossing around.

There is also a lot of chatter now, esp about deep dish carbon, and where the actual flex is, how it affects tracking and power etc, and spoke tension should be part of that conversation.

Another thing to consider is what the properties of the spokes Zipp uses are and if perhaps they are drawn to specific spec for their very specific use: Zipp rims. Of this I am not knowing.

I think tis is becoming a sidebar for another thread.

I have a pair of DT Swiss RR440 rims that I'm going to build up soon -- they have a spoke tension limit of 1200 Nm specified on the rim label (approximately 120 kgf).

I had a set of Zipp 404's with a PT that I built to the Zipp specs (which meant I limited the DS tension on the back to ~100kgf). The front wheel was fine, but I did experience an NDS spoke failure on the rear.