gyozadude

Not really. Jobst Brandt - book is held up as a bible for lots of beginners who are looking to study wheels. But in reality, he gets basic Physics sometimes wrong. The load zone is distributed to more than the single group of 4 spokes. It is a distribution. What he often repeats as "insignificant" change in spoke tension is due to his inability to measure the tension with accuracy.

Why? Because if you're a clyde and put 100 lbs of load on 36 spokes on the front, and 240 lbs in the rear (due to panniers and loaded gear), those spokes have to change tension to account for that load. Can't get around it. Laws of Physics. If I put load sensors on the hub axles, that's what they'd register. For each spoke, that might be just 0 - 10lbs each that's pre-tensioned to 200 lbs of tension each, but over 36 spokes, that's a shift with some spokes picking up 2% change and some changing some more.

And then there's the inconsistency in Brandt's books. He says that you can tension a spoke to the max to build a wheel and that makes the wheel hold the most stress. Furthermore, he tells the story that the spoke can take more tension than the rim can at the point because it could crack or fail or warp. And THEREFORE the rim is the weakest part of the wheel.

Ah hah! So all dilettantes read that and assume that the rim is the weakest thing. But how quickly and seemingly non-sequitur, Mr. Brandt mentions off hand that, IN PRACTICE, spokes are tensioned to only about a 1/3rd of maximum rim strength. He attributes this to possible torsion failure or non-lubed spoke nipples or some other thing. And he mentions further that builders need to be careful because it is possible to over tighten a spoke and pull it through the rim or warp the rim if the nipples are lubed.

Well, having years of building experience, I have yet to see a competent (human) builder cause spoke pull through even with lubed nipple threads because we never just tighten two spokes on opposite sides of the rim. We slowly go around and tighten spokes a bit each time. Even the section of the book talking about hub flange - spoke bend contact and direct line to the spoke hole in the rim are all non-issues for hand built wheels. It's as if he's writing the manual for guys building dumb machines that want to spoke just 32 holes and tighten the rim nipples just once.

That's not to say that most of what Jobst says is wrong. He's generally right. He does say is that tires affect stiffness. Rims in the whole scheme of things are NOT the cause of most failures. And he says it's spoke fatigue and pre-stress and not letting the spokes come loose that allows spokes to survive longer and the cause of long term wheel failure. And he basically confirms what all of us builders already know. More spokes means more distribution of stress, less stress and fatigue per spoke and therefore, longer life.

And in experience, unless you're riding and falling into grates daily, or hitting boulders and putting side load on the wheel, the number one mode of failure is fatigue leading to spoke breakage. And that's where having any decent rim with more spokes will help.

In the future, rather than just point to someone's book, why not cut/paste and cite actually what it says, or what you interpret it to mean in the context of how you read it. It doesn't help advance the discussion to tell someone to read the book. I know lots of competent wheel builders who make great wheels who never needed to read Jobst Brandt. As a scientist, engineer, AND mechanic (and I wasn't a software engineer for all of my career), I will put my bet on someone who DOES in reality and their experience far MORE than someone who has a book out. Anyone can research and write a book and do some experiments in a lab. Only until their theories are proven do I respect that, and even then, I respect the guys who build and put the stuff into practice than the folks that just sit and speculate.

And to remind myself, everytime I look at the $12 cheap Alex RP15F rims or X202 single walls that have gone a few thousand miles without failure or much tweaking at all, I wonder to myself: why do I have a huge stock of Velocity and Mavic rims hanging in the garage? I think it's about the "bling" factor more than anything else. It's maybe when folks come over with the Carbon Fibre bike and look upon my small shop, they will appreciate my prowess via the labels of my components. And then it gives my tendency to ride Real-Steel and be a retro-grouch half the time some credibility. Yeah, sure, I stock brifters too and ride them sometimes. But the having the "stuff" makes me cool.

But deep down, I can't escape the reality, that if I build a decent wheel with decent spokes, any rim can last a VERY long time regardless of price or advertised strength. My bets are on the builder and the quality of the spokes - which in PRACTICE are the weakest part of the wheel due to fatigue. The rims much less so.