Lacing triple cross 28h

[cribbit]

I've done 32h a few times. I normally do four at a time and it's pretty straightforward.

How do I do 28h triple cross? My brain isn't getting it and I'm struggling to find videos - I'm probably bad at searching.

[tctyres]

I've done 32h a few times. I normally do four at a time and it's pretty straightforward.

How do I do 28h triple cross? My brain isn't getting it and I'm struggling to find videos - I'm probably bad at searching.

Same way. 7 groups of four instead of 8.

Put down the spokes. Eat something and come back to it in an hour or tomorrow. It will be obvious.

[11.4]

Except that for a 28 spoke wheel you're somewhat better off doing it 2-cross rather than 3.

[cribbit]

Same way. 7 groups of four instead of 8.

Put down the spokes. Eat something and come back to it in an hour or tomorrow. It will be obvious.

I was doing 4 on the same side.

Except that for a 28 spoke wheel you're somewhat better off doing it 2-cross rather than 3.

I've been trying to look into this and finding no real information. Do you have a source / info on impact?

[ultraman6970]

28 triple cross?? depends a lot of the hub IMO because at 3x the spokes start overlapping a little bit more than what you really want.

[dddd]

I built up my Pacenti Brevit 28h rims onto these 7700 hubs the other night and was able to compare using 2x in front with 3x in back.

The 3x looks far better to me in terms of minimizing any cyclic changes in spoke tension due to drive torque on the rear hub.

https://farm8.staticflickr.com/7899/47335167601_73399d94d3_b.jpg

https://farm8.staticflickr.com/7847/47280572542_f9d1ec60af_b.jpg

FWIW, I was able to just get to 100kg driveside tension before any further tension increase tended to force the rear rim well out of true.
These are vintage-style rims that nevertheless "hit the numbers" in terms of credibly vintage profile, prodigious width and light weight.
As such, they are not going to build into as high-performing a structure as a rim with a modern profile, especially on an 8s, 130mm rear hub.
Very nice rims though, just what people have been asking for! Build weight was 1753g using 14/15G spokes and brass nipples.

[oldpotatoe]

I've done 32h a few times. I normally do four at a time and it's pretty straightforward.

How do I do 28h triple cross? My brain isn't getting it and I'm struggling to find videos - I'm probably bad at searching.

Same way to lace 28h, just instead of 'over, under', it's 'over, over, under'..with longer spokes it's easy. I do 'drop spokes' right side, turn wheel ovr, drop spokes other side..turn wheel over, rotate hub(either right for inside pulling or left for outside pulling), and then spokes inside out..lacing over, over, under.

Unless the hub flange diameter is large, I do 3 cross 28 on all rears, 2cross on fronts.

[tctyres]

I do what oldpotatoe does, so I don't know how you're lacing -- I drop all the "innies" in, flip over, and drop all the "outties" in.



I've been trying to look into this and finding no real information. Do you have a source / info on impact?

28 triple cross?? depends a lot of the hub IMO because at 3x the spokes start overlapping a little bit more than what you really want.

For a symmetrically drilled hub, divide the number of holes by 9 and round down. A 36h hub can be laced 4x without crossing another spoke hole. A 32h hub can be laced 3x without crossing another spoke hole. If you lace a 32h hub 4x, the spoke will cross directly behind or in front of another spoke hole.

Max crosses (symmetric hubs):
36h: 4x
32h: 3x
28h: 3x
24h: 2x
20h: 2x

Edit: Relative strength of the wheel in torque goes as crossings squared. A 4x rear has a multiplier of 16; 3x is 9, 2x is 4. This simple relationship explains why radially laced drive side spokes on standard road wheels always fail catastrophically. It's not a matter of "if" but "when." NB: This is a straight apples-to-apples comparison: same type of spokes, same rim sort of thing. Road front wheels see a lot less torque, so are often laced radially. Track front wheels ridden only on a track just about never see a torque because they are ridden on a dead flat surface. Lateral strength is mainly in the rim. The spokes just keep the hub centered laterally.

[cribbit]

So how do I decide between 2 cross and 3 cross? Front wheel, disc btw. Wouldn't 3 cross give me better strength for the torque of disc braking?

[oldpotatoe]

So how do I decide between 2 cross and 3 cross? Front wheel, disc btw. Wouldn't 3 cross give me better strength for the torque of disc braking?

Yes..no payback for 3cross and 28 unless big flanges..spoke overlap

[Mark McM]

Edit: Relative strength of the wheel in torque goes as crossings squared. A 4x rear has a multiplier of 16; 3x is 9, 2x is 4. This simple relationship explains why radially laced drive side spokes on standard road wheels always fail catastrophically. It's not a matter of "if" but "when."

This makes no sense; what wheels with crossed spokes don't have enough torsional strength? None that I know of. And where did this square of the crossings come from? And there are a number of wheels with radially laced drive side spokes, and they don't suffer from an inordinate number of broke spokes. (And how do spokes fail "catastrophically"? They either break, or they don't.)


NB: This is a straight apples-to-apples comparison: same type of spokes, same rim sort of thing. Road front wheels see a lot less torque, so are often laced radially. Track front wheels ridden only on a track just about never see a torque because they are ridden on a dead flat surface. Lateral strength is mainly in the rim. The spokes just keep the hub centered laterally.

Any front wheel without a hub break sees virtually no torque, road or track. Lateral strength relies on both the rim and the spokes, but the primary factor is the spokes - after all, they are the only thing that connects the tire/rim to the hub. With the same type or rim and hub, increasing the number of spokes dramatically improves wheel lateral strength.

[Mark McM]

So how do I decide between 2 cross and 3 cross? Front wheel, disc btw. Wouldn't 3 cross give me better strength for the torque of disc braking?

The decision between 2 and 3 cross with 28 spokes should primarily be determined by how the spokes interact with the hub flange. On some hub flanges, a 3 cross pattern may cause the spokes to overlap the heads of adjacent spokes, or may cause the spokes to overlap the flange too much, so a 2 cross may be better. With 28 crossed spokes, the individual spoke loading due to torques (driving or braking) is minimal, so the number of crossings has minimal effect on spoke longevity.

[tctyres]

This makes no sense; what wheels with crossed spokes don't have enough torsional strength? None that I know of. And where did this square of the crossings come from? And there are a number of wheels with radially laced drive side spokes, and they don't suffer from an inordinate number of broke spokes. (And how do spokes fail "catastrophically"? They either break, or they don't.)

Any front wheel without a hub break sees virtually no torque, road or track. Lateral strength relies on both the rim and the spokes, but the primary factor is the spokes - after all, they are the only thing that connects the tire/rim to the hub. With the same type or rim and hub, increasing the number of spokes dramatically improves wheel lateral strength.

I take catastrophe as more than one spoke breaks and/or the flange breaks from the stresses. There are plenty of radial nds rear wheels on the internet that show a "catastrophe." If one breaks, that's one thing. If they all break in unison, that's a catastrophe, and the rider is likely going to crash.

Tandem, loaded touring, and mtb wheels all come to mind as wheels that have additional torques.

Track wheels don't even have the torque from a brake. I consider 2x up front safety for braking and potholes.

Rims vs. spokes: Take a double walled aluminum rim and try to bend it with your hands one spoke length apart. Wheels flex all the time laterally in the spokes from hard pedaling.

I'll see if I can find the reference on the crossings, same with the lateral strength. It was a discussion with an engineer whose PhD was on the bicycle wheel. I will try to find his contact info.

[dddd]

Catastrophic failures due to radial spoking can be due to the added stress on the hub flanges pulling outward instead of tangent to the flange.

But then the real catastrophe occurs when (due to radial spoking pattern) a spoke flange breaks and then leaves two consecutive same-side spokes without tension. The localized force imbalance at the rim then prevents the wheel from even turning in the frame or fork.

Crossed spoke wheels that suffer a flange "explosion" of two spokes will lose tension in locations along the rim that are spread out enough to likely allow the wheel to keep turning.

[Mark McM]

I take catastrophe as more than one spoke breaks and/or the flange breaks from the stresses. There are plenty of radial nds rear wheels on the internet that show a "catastrophe." If one breaks, that's one thing. If they all break in unison, that's a catastrophe, and the rider is likely going to crash.

It is true that when a flange breaks with radial spokes, then it is likely that several adjacent spokes will be released. But that's more of an issue with the whether the hub is designed for radial spoke loads. But that's still a moot point, because if the spokes on the other flange are crossed, then the radial spokes experience no additional loads due to wheel torque.

Tandem, loaded touring, and mtb wheels all come to mind as wheels that have additional torques.

Please explain where these torques come from. The wheel bearings separate the wheel/hub form the rest of the bike and pass virtually no torque loads between the wheel and the fork/frame. Unless there is an additional coupling between the fork/frame and hub (such as disc or drum brake), then there is no significant spoke loading due to torques.

Rims vs. spokes: Take a double walled aluminum rim and try to bend it with your hands one spoke length apart. Wheels flex all the time laterally in the spokes from hard pedaling.

The rim is supported by the spokes, with only short spans between the spokes. The rim can not flex if the spokes don't flex, so the stiffness of the spokes will greatly affect the stiffness of the assembled wheel. Grab the two ends of a spoke, and try to stretch it. You'll find that the spokes are far stiffer than any rim.

Also consider this: The heaviest spokes weigh about 230 grams for 32 spokes - but for many wheels, the total weight of the spokes is about half of that. The weight of the lightest rims is about 280 grams - but most rims weigh far more than this. If you were to take a few dozen grams off of the rim on the average wheel, and add extra spokes equal to the same weight, I guarantee the wheel will have more lateral stiffness.

[tctyres]

It is true that when a flange breaks with radial spokes, then it is likely that several adjacent spokes will be released. But that's more of an issue with the whether the hub is designed for radial spoke loads. But that's still a moot point, because if the spokes on the other flange are crossed, then the radial spokes experience no additional loads due to wheel torque.


If this were true, there would be no nds failures, and there are. The hub transmits torques across it.


Please explain where these torques come from. The wheel bearings separate the wheel/hub form the rest of the bike and pass virtually no torque loads between the wheel and the fork/frame. Unless there is an additional coupling between the fork/frame and hub (such as disc or drum brake), then there is no significant spoke loading due to torques.

A torque is F*l = m*a*l. Change m or a, and the torque changes. Put another way, the torques come from the additional mass and accelerations associated with the loading. Cross and mtb riding requires instantaneous accelerations that are higher than a road bike. A loaded touring bike imparts extra torque from the extra mass. Brakes, chains, instantaneous accelerations on the wheel (positive or negative), associated with the road (e.g. potholes) all impart torques on the wheel.


The rim is supported by the spokes, with only short spans between the spokes. The rim can not flex if the spokes don't flex, so the stiffness of the spokes will greatly affect the stiffness of the assembled wheel. Grab the two ends of a spoke, and try to stretch it. You'll find that the spokes are far stiffer than any rim.

Also consider this: The heaviest spokes weigh about 230 grams for 32 spokes - but for many wheels, the total weight of the spokes is about half of that. The weight of the lightest rims is about 280 grams - but most rims weigh far more than this. If you were to take a few dozen grams off of the rim on the average wheel, and add extra spokes equal to the same weight, I guarantee the wheel will have more lateral stiffness.

The weight of the metal is irrelevant. A double walled rim is a hollow tube. A tube is hollow to increase its strength to weight. Furthermore, the discussion is on lateral strength so the lengthwise stretching is irrelevant. A set of spokes will flex inward/outward with hard pedaling. This why a brake can rub on a hard effort if the clearances are tight. If I had said radial or tangential, you'd be correct.

[oldpotatoe]

If you were to take a few dozen grams off of the rim on the average wheel, and add extra spokes equal to the same weight, I guarantee the wheel will have more lateral stiffness.

Of course..how to make a lighter, stiffer wheel? Light rim and sufficient spokes BUT that doesn't 'look' good on the LBS floor..marketeers make low spoke count wheels by increasing the rim weight a BUNCH(to make them reliable, sorta) and then use 18 spokes. BUT a little math...subtract 200 grams from that rim and add 14 spokes(32), which weigh about 3.5 OUNCES(120 grams or so)..but loses LBS and coffee shop points. :)

For right above..OMG..battle of the equations...:eek:

YOIKES!!

[ergott]

Torque is applied when driving the hub (rear wheel) and as a result accelerating the rim or braking at the hub and as a result a negative acceleration of the rim.

I'd like to see a picture of a 3X laced 28 hole wheel that has spoke overlap.

https://photos.smugmug.com/Cycling/Wheels/i-dTpPmbt/0/1a60e223/X3/_MG_1302-X3.jpg

[tctyres]

For right above..OMG..battle of the equations...:eek:

YOIKES!!

Sorry! I was trying not to ... but it happens. :(

[Lewis Moon]

I lace my 28s 3x all the time and have never had a problem. Perhaps if you have small flanges and the wheel is laced at less than optimal tension you might have overlap issues, especially on the NDS where the tension is the lowest.

[Lewis Moon]

Of course..how to make a lighter, stiffer wheel? Light rim and sufficient spokes BUT that doesn't 'look' good on the LBS floor..marketeers make low spoke count wheels by increasing the rim weight a BUNCH(to make them reliable, sorta) and then use 18 spokes. BUT a little math...subtract 200 grams from that rim and add 14 spokes(32), which weigh about 3.5 OUNCES(120 grams or so)..but loses LBS and coffee shop points. :)

For right above..OMG..battle of the equations...:eek:

YOIKES!!

I don't know why, but low spoke count wheels just look wrong to me. The same with "grouped" spokes. Give me a set of 28 - 32 wheels, Sapim DB spokes, DT hubs and Archtype(ish) rims any day. I'll ride them from gravel to hill climbs...and I'll have three sets shod with different tires for the same price as a set of fancy carbon wheels.

[oldpotatoe]

[QUOTE]I'd like to see a picture of a 3X laced 28 hole wheel that has spoke overlap.

[ergott]

not 28 spokes

[ergott]

If 28 3X was an issue I would have run across it long ago.

https://photos.smugmug.com/Cycling/Wheels/i-7FMf9dK/0/2a912b7e/X3/_MG_4823-X3.jpg

https://photos.smugmug.com/Cycling/Wheels/i-rWRRPZN/0/71b436e9/X3/20150423_185152-X3.jpg

https://photos.smugmug.com/Cycling/Wheels/i-hHqmc5X/0/c63685f6/X3/I9EnveM60-1-X3.jpg

https://photos.smugmug.com/Cycling/Wheels/i-HCrMqCx/2/a1bf602a/X3/Project321%20Enve01-X3.jpg

https://photos.smugmug.com/Cycling/Wheels/i-FbngBn7/0/d46b5167/X2/R45-Campagnolo-Pink-X2.jpg

https://photos.smugmug.com/Cycling/Wheels/i-fww8kSN/0/c8ab5d08/X3/Tommys%20Birthday34-X3.jpg

[Mark McM]

If this were true, there would be no nds failures, and there are. The hub transmits torques across it.

Spokes don't need torque loads to break The largest loads experienced by spokes are usually vertical loads (particularly when hitting bumps), and these can be sufficient to break spokes without the contribution of torque loads.

The hub only transmits torque loads if the spokes provide torsional stiffness. Since radial non-drive side spokes provide no torsional stiffness, they can't carry torsional loads, so torque is not transmitted across the hub. (Conversely, if the drive side spokes are radially laced, as on some Mavic Ksyrium wheels, the drive side spokes carry no torsional loads, and all torque is transmitted across the hub to the crossed non-drive spokes.) This is covered by several publications on wheel dynamics, including The Bicycle Wheel by Jobst Brandt.


A torque is F*l = m*a*l. Change m or a, and the torque changes. Put another way, the torques come from the additional mass and accelerations associated with the loading. Cross and mtb riding requires instantaneous accelerations that are higher than a road bike. A loaded touring bike imparts extra torque from the extra mass. Brakes, chains, instantaneous accelerations on the wheel (positive or negative), associated with the road (e.g. potholes) all impart torques on the wheel.

This is a tremendous reach. The wheel is a very small portion of the entire mass of the bikes. Plus, the wheel torques experienced are only those requred to accelerate the hub and spokes (the tire and rim are directly accelerated by ground contact forces), so those torques are very, very small (which is why I said "pass virtually no torque loads between the wheel and fork/frame). These torques are too small to have any meaningful effect on the spokes.


The weight of the metal is irrelevant. A double walled rim is a hollow tube. A tube is hollow to increase its strength to weight. Furthermore, the discussion is on lateral strength so the lengthwise stretching is irrelevant. A set of spokes will flex inward/outward with hard pedaling. This why a brake can rub on a hard effort if the clearances are tight. If I had said radial or tangential, you'd be correct.

Spokes support the rim by their lateral bracing angle. Clearly, without the spokes, a wheel whould have no lateral strength/stiffness at all. When a wheel is flexed laterally, the spokes are on either side are either stretched or 'compressed' (shortened by de-tensioning). The lateral movement is therefore constrained by the stretching/compressing of the spokes. As this article on wheel flex shows, even wheels with the stiffest rims have lateral flex, caused by spoke flex:

https://www.slowtwitch.com/Tech/Debunking_Wheel_Stiffness_3449.html

From the article:
When someone comments that their race wheel isn’t stiff enough, what they likely mean is this: Their wheel has too much lateral rim stiffness and not enough lateral spoke stiffness. That’s the big secret! You may feel compelled to say, “A-ha!”

How often do riders complain of their shallow-section aluminum wheels not being stiff enough? I don’t know about you, but I almost never hear that – short of a wheel with spokes that are far too loose. The reason you never hear that is because most aluminum wheels have relatively high spoke stiffness and relatively low rim stiffness. Think of wheel with 32 spokes of 2mm diameter, laced to a 20mm deep alloy rim – that’s a lot of spoke material and not much rim.

https://www.slowtwitch.com/articles/images/2/65632-largest_Mavic_wheel_bend.png

[tctyres]

Spokes don't need torque loads to break The largest loads experienced by spokes are usually vertical loads (particularly when hitting bumps), and these can be sufficient to break spokes without the contribution of torque loads.


The vertical load is mainly constant as the weight of the rider + frame doesn't change appreciably over the course of a ride. Hitting a bump is vertical but can cause a torque if there is an acceleration off the vertical plane, and there almost always is.


The hub only transmits torque loads if the spokes provide torsional stiffness. Since radial non-drive side spokes provide no torsional stiffness, they can't carry torsional loads, so torque is not transmitted across the hub. (Conversely, if the drive side spokes are radially laced, as on some Mavic Ksyrium wheels, the drive side spokes carry no torsional loads, and all torque is transmitted across the hub to the crossed non-drive spokes.) This is covered by several publications on wheel dynamics, including The Bicycle Wheel by Jobst Brandt.


A torque can be transmitted across a hub with radial non-drive side spokes. This is the issue as to why they break. If the torque is transmitted, those spokes cannot support it either leading to elastic flexure or plastic failure. There aren't other options with a radial lacing. For a cross-laced wheel, the torque can be transmitted to the rim, which is where the rider wants it.


This is a tremendous reach.


Ha! Using the definition of a torque is a reach. I guess if you don't know physics, it might seem like it.


The wheel is a very small portion of the entire mass of the bikes. Plus, the wheel torques experienced are only those requred to accelerate the hub and spokes (the tire and rim are directly accelerated by ground contact forces), so those torques are very, very small (which is why I said "pass virtually no torque loads between the wheel and fork/frame). These torques are too small to have any meaningful effect on the spokes.



The average acceleration of the wheel is the average acceleration of the bike. If you're thinking only about the wheel, that's the problem. The wheel rotates over the ground (no-slip condition) and translates the hub.


Spokes support the rim by their lateral bracing angle. Clearly, without the spokes, a wheel whould have no lateral strength/stiffness at all.


The bracing angle is tiny, so transmits little force laterally.

[dddd]

...The bracing angle is tiny, so transmits little force laterally.

All of the lateral force that a wheel sustains is from the product of spoke bracing vector and the multiple spoke's relative inelasticity.

These forces can be quite substantial, certainly enough to bend the rim outright but for the effective later bracing provided by the spokes.

Also, the bracing angle on the drive side has to provide a balancing equal force to the better-braced non-drive spokes, which may help one to visualize how substantive that the forces are.

[cribbit]

Is this thread now a battle between wheel and equations porn?

[oldpotatoe]

Is this thread now a battle between wheel and equations porn?

Oh yeah? Take this.:eek:

What's scary is one or both of these guys will look at this and know what it means..:p

[Mark McM]

The vertical load is mainly constant as the weight of the rider + frame doesn't change appreciably over the course of a ride. Hitting a bump is vertical but can cause a torque if there is an acceleration off the vertical plane, and there almost always is.

The vertical load can be magnified when hitting a bump to a very large value (consider - hitting a sharp edge bump can compress the tire enough to pinch flat it, which takes a very large instantaneous force). But perhaps more importantly, the vertical force only affects a few spokes near the LAZ (Load Affected Zone) at the bottom of the wheel, whereas torques are distributed nearly evenly across all crossed spokes.



A torque can be transmitted across a hub with radial non-drive side spokes.

As stated before, no torque is transmitted across the hub with radial non-drive side spokes. The reason is explained in the book "The Bicycle Wheel" by Jobst Brandt. The rest of the world agrees with this, and here are some examples:

Sheldon Brown's guide to wheel building says that radial lacing the non-drive side spokes can sometimes be an advantage because then these spokes experience no torque loads:

https://www.sheldonbrown.com/wheelbuild.html#half-radial

Here is an paper on the Williams Cycling web site, featuring an analysis of spoke loading with different lacing patterns. They also conclude that radial non-drive spokes transmit no torque:

http://www.williamscycling.com/assets/images/product%20tech/Bicycle%20Wheel%20Spoke%20Lacing.pdf

The Wheel Fanatyk blog (https://www.wheelfanatyk.com/blog/wheel-trick-four-power/)also says this about radial non-drive spokes:

There must be a million road bikes with 24 hole rear wheels. Most of them have radial patterns on the non-drive side for style and aerodynamic bling. Radial can transmit no torque until a tiny windup. Since the drive side, crossed pattern is rotationally stiffer it carries the torque load before the poor non-drive side gets a chance. It’s not unwilling, just too slow. The rear wheel’s left side is completely unable to assist for torque loads. All it can do is carry vertical weight, for which the whole unit is grateful.

And you don't have to take their word for it, you can verify it with your own test. Take a bike with a rear wheel that has radial non-drive side spokes and put the drivetrain into it's lowest gear ratio. Have a friend clamp the rear brake (to keep the wheel from turning) and stand on the forward pedal with the crank horizontal to generate a torque load on the wheel. On the drive side, pluck spokes on both sides at the top of the wheel and listen for the tone they make - the pitch of these tones with vary with spoke tension. Compare the tones on each spoke with and without torque applied to the wheel. You should find that tones of drive side trailing spokes increase in pitch under torque load (increase tension), while the tones of drive side leading spokes decrease in pitch (decrease tension), but there should be no change in tone in the radial non-drive spokes (no change in tension). If the non-drive side spokes don't change tension, they are not transmtting torque loads.



The average acceleration of the wheel is the average acceleration of the bike. If you're thinking only about the wheel, that's the problem. The wheel rotates over the ground (no-slip condition) and translates the hub.

The translational acceleration at the hub from the wheel weight is also very small, and besides, translational accelerations don't generate torques.


The bracing angle is tiny, so transmits little force laterally.

This very obviously can not be true. The tire & rim are only connected to the rest of the bike by the spokes. Therefore all forces (lateral, vertical, and torsional) between the hub and rim must be transmitted by the spokes, and only by the spokes.

[Mark McM]

Oh yeah? Take this.:eek:

What's scary is one or both of these guys will look at this and know what it means..:p

That's the formula for spoke length, where d = radius of rim (ERD/2), r1 = flange radius, r2 = flange offset, a = spoke angle (= 720 degrees x number of crosses / number of spokes), and r3 = radius of the flange spoke hole.

[cribbit]

That's the formula for spoke length, where d = radius of rim (ERD/2), r1 = flange radius, r2 = flange offset, a = spoke angle (= 720 degrees x number of crosses / number of spokes), and r3 = radius of the flange spoke hole.

I thought spoke length came from the magical all-knowing website calculator.

[ergott]

The vertical load can be magnified when hitting a bump to a very large value (consider - hitting a sharp edge bump can compress the tire enough to pinch flat it, which takes a very large instantaneous force). But perhaps more importantly, the vertical force only affects a few spokes near the LAZ (Load Affected Zone) at the bottom of the wheel, whereas torques are distributed nearly evenly across all crossed spokes.

I know I read this in his book too, but I have a bone to pick with that theory. What about the tire and air? If you compress the tire before the point the rim comes in contact with the other side of the tire/tube (pinch flat) that air cushion is spreading the load across a far greater area than the LAZ. Seems to me that the FEM drawing depicts a rim hitting the ground, not tire/tube.

[oldpotatoe]

I thought spoke length came from the magical all-knowing website calculator.

Works for me...

https://leonard.io/edd/

https://www.wheelpro.co.uk/spokecalc/

https://bikeschool.com/index.php/resources/spoke-calculator

Who remembers the ''good' old days' with Sutherlands 5th edition?? Chapter 11..kinda like celestial navigation..but harder..:eek:

[speedevil]

I put together a post about spoke length calculations on my blog. Take a look at this.

Calculate bicycle spoke lengths the old way (https://www.dalemorin.com/?p=1324)

[oldpotatoe]

I put together a post about spoke length calculations on my blog. Take a look at this.

Calculate bicycle spoke lengths the old way (https://www.dalemorin.com/?p=1324)

L = sqrt(R^2 + H^2 + F^2 – 2RHcos(360/h*X)) – shd/2
Check it out, it’s not really that complicated.

REALLY?? Thanks for this but for this business major..I'll stick to measuring the hub and rim and use an online 'program'...

[speedevil]

REALLY?? Thanks for this but for this business major..I'll stick to measuring the hub and rim and use an online 'program'...

I get it - I was mainly curious about how the lengths were calculated. With a minor in mathematics, seemed reasonable. it's nice sanity check for the online calculators.

[Mark McM]

I know I read this in his book too, but I have a bone to pick with that theory. What about the tire and air? If you compress the tire before the point the rim comes in contact with the other side of the tire/tube (pinch flat) that air cushion is spreading the load across a far greater area than the LAZ. Seems to me that the FEM drawing depicts a rim hitting the ground, not tire/tube.

Modeling the force at the ground as a single point load was of course a simplification to make the FEA easier (Brandt originally did this work in the 1970's when FEA was less developed). His analysis was mostly to demonstrate general principles of how wheels work. Since then, direct measurements of spoke tensions changes in actual wheels (with tires installed) have shown the general principles shown in Brandt's analysis apply in the real world.

Below is a link to paper by Henri Gavin of Duke University, who studied stress/strain in bicycle spokes to see how lacing pattern (number of crossings) influenced spoke fatigue. In this paper, Gavin compared mathematical models of spoke loads to direct measurements on wheels (tires installed) with the spokes instrumented with strain gauges. He measured the strains in the instrumented wheels both statically and dynamically (actually riding the wheels on the road). He found that the tire did act to spread the load over a short span of rim, and the peak spoke strains on the real wheel were a bit smaller than in the models that used a point load; but just like the numerical analyses predicted, the vertical load was distributed only among a small number of spokes at the bottom of the wheel, and was especially concentrated on the bottom most spoke.

http://people.duke.edu/~hpgavin/papers/HPGavin-Wheel-Paper.pdf

[Mark McM]

I get it - I was mainly curious about how the lengths were calculated. With a minor in mathematics, seemed reasonable. it's nice sanity check for the online calculators.

Using on-line pre-programmed spoke length calculators is fine when using standard components and lacing patterns, with equally spaced spoke holes on hubs and rims. But some wheels use non-standard patterns or non-standard spoke spacing. In these cases, you have to go back to the fundamental formulas and make the necessary adjustments for the non-standard geometries. This may be case even when starting with 'standard' components, such as making a 24 spoke triplet laced wheel with a standard 32 hole hub and 24 hole rim.

[oldpotatoe]

I get it - I was mainly curious about how the lengths were calculated. With a minor in mathematics, seemed reasonable. it's nice sanity check for the online calculators.

Why I use 3..I check thru all 3 before I start to cut spokes..:)

But as an aside..one thing that is really vexing these days is the YUGE variableness of spoke holes in the hubs..I try to 'predict' those which has a big effect on spoke length(for this guy who is picky about 1mm differences) but, altho not really 'bitten' yet, I have built 2 shimano rear hubs and found the spoke holes bigger than previous iterations(SLX and XT)..Why I tend to 'round down' with shimano, Bitex, Dynamo type hubs(Dynamo cuz the holes are counter sunk..)...

[Dasarbule]

Why I use 3..I check thru all 3 before I start to cut spokes...

...for everything else, there is Mastercam...

[oldpotatoe]

...for everything else, there is Mastercam...

??

[Dasarbule]

For some combinations, especially when reusing proprietary straightpull hubs, i like to do a simple centerline 3D Drawing using Mastercam to check spoke length calculations.