SquidPuppet

What's going on there?

FBinNY 

Either a time/cost saving measure on a production wheel. Or an intentional hand built wheel for track where rigidity trumps resilience/longevity.

I don't weave spokes when building for small tracks or sprinters.

There are no rules in wheelbuilding, only considerations.

SquidPuppet

This part confuses me. I think I understand why it would be more rigid. But wouldn't more rigid equal less fatigue from flexing, and therefore longer lasting? Splain me please.

FBinNY 

Any consideration of service life on a track wheel is a meaningless joke. How many miles do track wheels see in a human lifetime? How much shock from bad pavements?

It's a TRACK wheel, so only performance on the track matters.

A I said -- no rules, just considerations.

Bandera

Agree.
I learned wheel building from a Master of tied & soldered track wheel building in pre-WWII racing.
You either know what you are doing or Not from actual experience.

We built light wheels for road Nationals on the "American" pattern that did just fine "back when" for our riders w/ the "new" mid-70's 6 cog tech 32hole wheels.
Not a huge surprise for us, with the touch that we were taught by "Pop" who had a signed pic of Jimmy Walthour Jr. by his workstation.

edit: Glancing into the garage two machines are still on the mid-80's front wheel built for them, and if a FG RR wheel wasn't required for one and a 10 cog cassette for the other they would still be rocking the same '80's build w/ zero worries.

Craftsmanship: Period, End.

-Bandera

Ed.

Paramount

SquidPuppet

Unless I am reading your post wrong, you strike me as agitated.

I wasn't questioning your knowledge, I was politely asking a question. A serious one. Which you didn't answer.

My understanding is that the cause of spoke breakage is due to repeated flexing cycles. I also wasn't sure why the OOOO would be more rigid. If the wheel is more rigid wouldn't that make for a longer life? I was hoping to tap your knowledge and learn something.

FBinNY 

No, I was trying to hammer home a point.

As for flex, you may be looking at it the wrong way. Wheels don't actually move enough, for flex to make a difference. Possibly road wheels used hard might, given that they see plenty of side loading, but even there, 1-2mm movement at the rim would be an awful lot, and what does that translate to at the hub end?

Fatigue is caused by the repeated changes in tension as the wheel moves under load. So it's not shape changes, but changes in load that matter. The elbows break because the tension stresses are at right angles (shear), so they act as a stress riser, and break the same way a notch would be anywhere in the wire.

There's also some movement as the tension changes, but it's hard to explain without a sketch. However, if you accept that the elbow is poorly supported in the flange, pulling the spoke down would cam the short leg in the spoke hole changing the bend at the elbow. This is why builders prefer tight spoke holes and the spoke to lie against the flange as much as possible.

So when you think "flex" think in terms of the spoke getting longer and shorter, not bending sideways.

I hope that helped.

RobbieTunes

As long as they look good, I'm fine.

SquidPuppet

Nope. I am looking at it exactly the way you describe below. I was wording it all wrong by using the word "flex".

I think of it as stretched-released-stretched-released-repeat-repeat-repeat. Don't know why I used "flex".

This part I have always understood too.

So I still don't understand two things and would like to learn.

1. How does eliminating the weave at the final cross make the wheel more rigid?

2. And does that particular increase in rigidity affect the amount of tension change the wheel experiences?

FBinNY 

I can answer both, but you'll have to finance a sketch pad. but I'll try.

I think you can see that an unwoven spoke runs straight and true to the rim.

But consider what happens with the weave (or look at your wheel. Each spoke is no longer straight. Instead it has a slight bend at the last cross. This means that if/when the tension increases the spoke tries to straighten, pushing it's mate out of the way. By the same token, when tension is eased, it relaxes and let itself get bent more as the mate straightens.

This ability to straighten and relax by working with the mate means that the peak tension changes felt at the ends is mitigated, sort like how the crushing styrene in your helmet reduces the Gs to the brain.

SquidPuppet

This part pulled it all together for me. Thanks.

old's'cool

This



and this

are good info.

FBinNY 

You're welcome, and see ---- I wasn't angry.

The hard part in explaining this kind of stuff in a forum is you never know what people are getting, where they got lost, and the particular bit that they're missing.

I prefer teaching in person, where I an watch people's eyes and adjust the presentation accordingly. I also get to use sketches and physical props to demonstrate principles.

Ed.

Nope, just from New York

FBinNY 

It's all theater.

Sometimes you come on angry or frustrated and suddenly people think you're serious and start listening.

Folks in the NYC cycling community might remember Lenny Prenheim of Toga Bike Shop. He was the absolute master of using dramatics to get attention. Lenny was a good friend for years and ranks near the top of old cycling friends I miss these days.

unterhausen

I used to be absolutely convinced that the pulling spokes should be elbows out/heads in. So much so that I would start over if I had a lapse of attention. Fast forward to recent times, and I find out that the conventional wisdom has reversed. So I start building them elbows in. The elbows out wheel on my main bike from the early '80s lasted 30 years of hard use. My conclusion is that it doesn't actually matter. But now I do things like line up the logo with the valve hole because some people are ridiculous and I don't want to give them anything to notice before they go away and bother someone else. It's the wheelbuilding equivalent of nodding in agreement and backing away slowly.

As far as how you lace a wheel, I've watched videos of factory people lacing wheels. I really think my method could be just as fast or faster with a lacing stand and a little practice. I put all the inward facing spokes and then the outward facing spokes. This means there is only the final overlap. They are overlapping each spoke from what I see. I'm amazed that they can keep things straight. I used to be able to build a wheel in 5 minutes, and that was without a lacing stand

Salamandrine 

I really don't think they thought about it that much BITD. Asymmetrical is just the old school way of doing it. It is very fast, faster than symmetrical. You put all the spokes in at once till you get this big porcupine thing and go. It seems awkward but it works. I built my first set of wheels asymmetrical following directions in a book when I was 14. They were fine. IIRC I used it on couple occasions after than when I needed to build a couple sets of cheap wheels fast.

Prowler 

T'aint that simple. Should the logo be right side up or upside down? Should the tail on the Campagnolo g be trailing or leading? Effects aerodynamics and laminar flow across the hub surface. The amount of metal removed during the engraving could impact right/left balance of the hub. We need scientific data, algorithms, computer modeling, double blind tests, verification use cases and 3D simulations.

Not just higgly-piggly "always done er dat way" past down thru the ages traditions. Sheeeeeeesh!

Say, is there an emoji for "higgly-piggly traditions"?

realsteel

Here is a scientific study published in Journal of Engineering Mechanics , August 1996, Vol. 122, No. 8 : pp. 736-742: https://dx.doi.org/10.1061/(ASCE)0733...1996)122:8(736)

Bicycle-Wheel Spoke Patterns and Spoke Fatigue
Henri P. Gavin, Associate Member, ASCE
Asst. Prof., Dept. of Civ. Engrg., Duke Univ., Durham, NC 27708-0287.

The radial, lateral, and tangential stiffness of spoked bicycle wheels depends
upon the rim's bending inertia, torsional inertia, the spoke sizes, and the
spoke geometry. The spokes of three rear bicycle wheels of different spoke
patterns were instrumented with strain gauges in order to investigate the
effect of the spoke pattern on the spoke strain and fatigue resistance
properties of the wheels. Spoke strains due to radial loads were measured in the
laboratory. Time records of the strain of a right pulling spoke were collected
from each of the wheels under actual riding conditions. Analytical, numerical,
laboratory, and field studies show that spoke strains due to radial loads and
in service conditions are insensitive to the spoke pattern. Small variations in
the spoke strains between the wheels in the road tests can be attributed to
variations in the loads, but do not significantly affect the fatigue life of
the wheels.

(emphasis mine)

jimmuller 

Regardless, or if you prefer, irregardless, of the intended humor , I've had a big problem with this. Most of the used Campy hubs I've strung up had been strung previously such that I could not reuse the same spoke directions through the holes and get the logo to line up as I wished. Oh the grief that has caused. I hate being stopped by the style police when I'm trying to beat my best time on some course.

SquidPuppet

Oh my.

crank_addict

I admit to incorrectly building some wheels, nothing though that could be redone and I'm always learning. My primary guideline was from using Sloane's Bike Book, over - over - under.

My peave and frustration is how to correct a rim with a slight flat spot. Once tried to use a plywood jig to re-shape curvature and ended up hairline fracturing the rims sidewall.

Wilfred Laurier

I build with elbows in, heads out. I find lacing rear wheels is easier this way when it comes time to do the twist.

cyclotoine

I do as well, unless it's a used hub then I'll USUALLY follow the previous pattern to hide markings, though I have deviated from the previous pattern if the marks are faints. Never had a problem either way. Every wheel I've built has remained rock solid often not needing to be trued for 1000s of kms.