Cycling UK Forum

JohnR wrote: ↑31 Oct 2023, 5:26pm

531colin wrote: ↑31 Oct 2023, 1:15pm I have never used threadlock on a bike wheel nipples. The occasional customer wanted “self locking” nipples, like nylock nuts, which fought you all the way up the thread…horrible things! I can see a need for threadlock in lightweight highly dished wheels (say 130 mm OLN 11speed with a narrow light rim without offset spoke holes) where the left spokes are likely to go slack when the wheel is ( variously) loaded, but I never found it necessary on touring wheels. Most people lubricate the nipples before building…I stopped doing that.

FWIW, I've been told that Thorn/SJS normally build wheels using boiled linseed which both acts as a lubricant and stops the nipples loosening.

IIRC then on the few wheels that I’ve built over the years the threads have been cleaned and un-lubricated. I’m not sure but vaguely recall some folk saying to use a very light oil on build and that nipples eventually seizing onto the spokes wasn’t a good idea (stops an old wheel being re-trued). Perhaps what was needed with pre-stainless steel spokes was different. If I’d had an oil to hand that cured or gummed up with age then maybe that would have been better. Loctite do a low strength product (222 https://www.henkel-adhesives.com/us/en/ ... ocker.html) and I’d wondered about using that on future projects.

Spokes get twist in them (like a torsion spring) and that can result in the wheel going out of true later. The later wheels I’ve built have had the wheels laid on their side and supported at the flanges, I’ve then pressed down on the rims (obviously all around) to either seat or unload the spokes (turn over and do both sides). The resultant wheel will be out of true, but true it up again and it’ll likely stay good. Well, works for me.

I’ve only ever built with plain gauge spokes, doubtless double butted is better but plain gauge has been adequate for my use and it’s been what I had to hand. I’d now used double butted if I had the right length to hand, as per the Spa way. Double butted ain’t cheap though, so you’d better be right first time on the spoke length.

Can’t say that what I’ve built has been the best possible result, just saying this is what I’ve done and that it worked (been adequate) for me. Maybe what helps is not demanding too much of stuff. I’m not a powerful rider, don’t go fast, don’t use particularly narrow tyres, do avoid narrow rims *, and do tend to pick a ‘kind’ route through/over uneven surfaces.

* on a traditional road bike I now like to use near the widest combination of tyre and rim that’ll comfortably fit between the chain stays. Such a combination has proved to be durable in my use and slightly narrower/lighter didn’t - for my use on my bikes a couple of extract mm width here and there has made a significant and positive difference … my spoke keys now gather dust .

Carlton green wrote: ↑1 Nov 2023, 6:11am I’ve only ever built with plain gauge spokes, doubtless double butted is better but plain gauge has been adequate for my use and it’s been what I had to hand.

I’ve always thought PG spokes broke the ‘strong, light, cheap - pick two’ rule as they’re neither strong nor light. Usually reserved for penny pinching bike manufacturers rather than anything you’d bother with when building your own wheels.

TheBomber wrote: ↑1 Nov 2023, 8:18am

Carlton green wrote: ↑1 Nov 2023, 6:11am I’ve only ever built with plain gauge spokes, doubtless double butted is better but plain gauge has been adequate for my use and it’s been what I had to hand.

I’ve always thought PG spokes broke the ‘strong, light, cheap - pick two’ rule as they’re neither strong nor light. Usually reserved for penny pinching bike manufacturers rather than anything you’d bother with when building your own wheels.

Traditionally all bikes were built with plain gauge spokes and folks covered many thousands of miles on such wheels without wholesale or even common one-off failure. When a spoke did break you just fitted another, folk often had a few spares for the back wheel tied to their frame. Some spokes were better made than others and some wheels better built than others but PG spokes certainly can do the job, it’s just that other stuff can do it better. Do we always need better? I don’t find so, adequate is enough for me.

PG aren’t light, they’re heavier than double butted, but they are strong and they are cheap(er). When they fail - could be years before a spoke failure and you may never have one - then spokes tend to break at or near to their head, but there are ways to help that failure not to happen / load the dice in your favour.

I too didn't break any spokes in wheels I built, well not after ~1985 anyway [and they were duff spokes]. Nor did I know of any breakages in wheels I built for other people,despite asking them to report any such occurrence. IME PG spokes are usually 'strong enough' in a well-built wheel.

Carlton green wrote: ↑1 Nov 2023, 6:11amSpokes get twist in them (like a torsion spring) and that can result in the wheel going out of true later.

You're supposed to be removing that when you build the wheel. It's quick and easy if you mark the ends of the spokes with a felt tip pen before you start tensioning, then you don't have to try to do it by feel.

-or you could make little flags on each spoke using sticky tape

Carlton green wrote: ↑1 Nov 2023, 6:11am ……………
Spokes get twist in them (like a torsion spring) and that can result in the wheel going out of true later. The later wheels I’ve built have had the wheels laid on their side and supported at the flanges, I’ve then pressed down on the rims (obviously all around) to either seat or unload the spokes (turn over and do both sides). The resultant wheel will be out of true, but true it up again and it’ll likely stay good. Well, works for me………………

Laying the wheel down and pressing down on opposite sides of the rim, all the way round, both sides, with a fair bit of your body weight?**
That’s what I call “stressing the wheel” and it’s part of my final repeating cycle…….stress the wheel, true the wheel, balance the tension…… repeat repeat repeat to get an acceptable compromise between dished/round/true/even tension.

At the same time, you will get rid of spoke wind up…. However, wind up is completely harmless, you just get a bit of tinkling for the first couple of yards.
If you don’t stress the wheel (etc) it will go out of true and it will have wound up spokes; but these are 2 separate things, not cause and effect.
**this is when you feel the difference in stiffness of either side of a dished wheel

To minimise wind up when building, to make 1/4 turn correction, go “almost half a turn and back a bit”….you soon get the feel for it

that is pretty much what I used to do. However you can't always be entirely certain of what was and wasn't turning. So I developed a strategy whereby I would [in the final stages of truing] feel for the wind-up with my other hand.

531colin wrote: ↑31 Oct 2023, 11:10am I’m away from home so reliant on my 76 year old memory, which is never a good thing.
However, I’m pretty sure Brandt doesn’t tell us whether his finite element analysis refers to fifties style single channel rims, or more recent hollow box section rims.
As I recall he doesn’t mention hollow box section rims much; there is a diagram , but I don’t remember him mentioning how much stiffer the box section rims are.
I have assumed the finite element analysis refers to single channel rims, because of the date of publication and because that’s what he illustrates.
If that assumption is correct, then Brandt’s analysis doesn’t have much relevance to modern rims

I have the book in front of me, and can confirm Brandt doesn't say which design of rim he used in his calculations. However he does have a section on rim design in which all modern designs of rim (apart from extreme deep section aero designs) are illustrated and their properties discussed. He says (and FWIW I think he's right) that a 'sprint' rim for tubular tyres ('sew-up' in American) is the structurally optimum design, as it's the closest practical shape to a rectangular box-section. And most of his illustrations of wheels show this kind of rim, so I think it's most likely that his calculations are for this type too.

Tubular tyres have fallen out of popularity as the rolling properties of beaded tyres have improved, and Brandt's second-best design of rim now dominates the market. It's second best because the well and flanges required to retain a beaded tyre contribute little to the radial bending and almost nothing to the torsional stiffness of the rim, so the hollow box part cannot be so big without adding weight. In Brandt's day the sides of the rim also had to withstand a certain amount of braking wear, so those hollows weren't so big. Now that we have disc brakes however, the walls of the hollow can be thinner and its volume increased without adding weight. So I would guess that we're just about back to parity with the sprint rims of yore, torsion wise.

Without doing the maths - which is fearsomely difficult - but thinking about the form of the equations that must govern these displacements, lateral bending stiffness is probably more important in resisting small lateral displacements that lead to small lateral deviations from truth. Torsional stiffness will take over in the later stages of buckling, in resisting spread of the buckle around the rim and eventual collapse. But by then perhaps, it's game over anyway!

The good news (and I'm arguing on your side now Colin) modern rims surely WILL be better than Brandt's calculations (and touring rims always were) thanks to the rise of gravel biking and a new found fondness for wider rims amongst both mountain-bikers and roadies, for whom the 'new narrow' is 17mm, same as the tourist's old standard! This loosening of belts amongst our nose-down brothers also seems to have made it easier for tourists to move up a size, to the 19mm rims and 37mm tyres that have always made better sense for the imperfect surfaces of the back roads and bikepaths we prefer.

So perhaps we can better tolerate a simplistic spoking structure. But I think touring bikes should not only be well-made, but also well designed, with more material where the forces are higher. So rather than spoil the ship for a ha'porth of tar, I will continue to recommend proportionally thicker spokes (or more spokes) where the tension is necessarily high and thinner (or fewer) where it's low. Not only does that equalise the stress, but also the elongations, removing the risk of spokes on the slack side loosening. (I have never used threadlock and never wished I had.) And AFAIK nobody who's followed my advice has ever complained.

531colin wrote: ↑31 Oct 2023, 11:10am I’m away from home so reliant on my 76 year old memory, which is never a good thing.
However, I’m pretty sure Brandt doesn’t tell us whether his finite element analysis refers to fifties style single channel rims, or more recent hollow box section rims.
As I recall he doesn’t mention hollow box section rims much; there is a diagram , but I don’t remember him mentioning how much stiffer the box section rims are.
I have assumed the finite element analysis refers to single channel rims, because of the date of publication and because that’s what he illustrates.
If that assumption is correct, then Brandt’s analysis doesn’t have much relevance to modern rims

I have the book in front of me, and can confirm Brandt doesn't say which design of rim he used in his calculations. However he does have a section on rim design in which all modern designs of rim (apart from extreme deep section aero designs) are illustrated and their properties discussed. He says (and FWIW I think he's right) that a 'sprint' rim for tubular tyres ('sew-up' in American) is the structurally optimum design, as it's the closest practical shape to a rectangular box-section. And most of his illustrations of wheels show this kind of rim, so I think it's most likely that his calculations are for this type too.

Tubular tyres have fallen out of popularity as the rolling properties of beaded tyres have improved, and Brandt's second-best design of rim now dominates the market. It's second best because the well and flanges required to retain a beaded tyre contribute little to the radial bending and almost nothing to the torsional stiffness of the rim, so the hollow box part cannot be so big without adding weight. And in Brandt's day the sides of the rim also had to withstand a certain amount of braking wear, so those hollows weren't so big. Now that we have disc brakes however, the walls of the hollow can be thinner and its volume increased without adding weight. So I would guess that we're just about back to parity with the sprint rims of yore, torsion wise.

Without doing the maths - which is fearsomely difficult - but thinking about the form of the equations that must govern these displacements, lateral bending stiffness is probably more important in resisting small lateral displacements that lead to small lateral deviations from truth. Torsional stiffness will take over in the later stages of buckling, in resisting spread of the buckle around the rim and eventual collapse. But by then perhaps, it's game over anyway!

The good news is (and I'm arguing on your side now Colin) that modern rims surely WILL be better than Brandt's calculations - and touring rims always were - thanks to the rise of gravel biking and a new found fondness for wider rims amongst both mountain-bikers and roadies, for whom the 'new narrow' is 17mm, same as the tourist's old standard! This loosening of belts amongst our nose-down friends also seems to have made it easier for tourists to move up a size, to the 19mm rims and 37mm tyres that have always made better sense for the back roads and bikepaths we prefer.

So perhaps we can better tolerate a simplistic spoking structure. But I think touring bikes should not only be well-made, but also well designed, with more material where the forces are higher. So rather than spoil the ship for a ha'porth of tar, I will continue to recommend proportionally thicker spokes (or more spokes) where the tension is necessarily high and thinner (or fewer) where it's low. Not only does that equalise the stress, but also the elongations, removing the risk of spokes on the slack side loosening. (I have never used threadlock and never wished I had.) And AFAIK nobody who's followed my advice has ever complained.

CJ wrote: ↑2 Nov 2023, 11:14am

531colin wrote: ↑31 Oct 2023, 11:10am .......If that assumption is correct, then Brandt’s analysis doesn’t have much relevance to modern rims

I have the book in front of me, and can confirm Brandt doesn't say which design of rim he used in his calculations.

there are several editions of Brandt's book; they may not be all the same as one another.

However ISTR him talking about 'freely hinged segments' or somesuch? I do not have it in front of me, so I can't really check anything.

Brucey wrote: ↑8 Nov 2023, 4:06pm ISTR him [Brandt] talking about 'freely hinged segments' or somesuch? I do not have it in front of me, so I can't really check anything.

I think you may be misremembering: "The computation of the deflections for various load combinations are based on a matrix solution of the wheel divided into finite elements such that the rim has three degrees of freedom at each each spoke", or misinterpreting what is meant by "degrees of freedom". It means that these points are not taken as fixed in space, but can move in any direction relative to the hub (which presumably IS fixed), subject to the forces applied to the rim and constraints of the material properties entered into the model. As Brandt goes on to say: "the rim and spokes have their actual structural properties of elasticity and bending stiffness".

I'm just a simple biologist, but I'm at home with my copy of Brandt.

He considers the rim as having 36 "nodes" where each spoke joins the rim.
He writes; "The 36 active nodes at the rim and spoke junctions are given three degrees of freedom. They can move tangentially, radially, and rotationally in the plane of the wheel. These displacements are computed for each node."
The "are given" strikes me as an odd way of phrasing it, I understand when he writes "These displacements are computed for each node."

He also writes; " The rim elements have a resistance to bending, tension, and compression, while the spokes resist only tension."

I can't find anywhere he refers to the stiffness of the rim he uses for the calculations, or even the type of rim.

He also writes "The rim is divided into 36 short structural beams that reach from spoke to spoke." He surely means his calculations are based on those "short" beams acting as a single structure, he can't mean they are able to move relative to each other, like a hinge joint?

CJ wrote: ↑8 Nov 2023, 10:21pm....I think you may be misremembering......

it wouldn't surprise me in the slightest.