spoke threading question (cracks in rim)

[FMB42]

Im not sure you read/understood properly.....I have both a 20" wheel bmx ebike and a bigger 26" wheel ebike. both with the same size/power hub motor and 1500w controller.
ive only just relaced the 20" after it being OOA for the past yearish (dented rim lip from flatish tyre+rough ground, not bad spoke holes).
the old 20" rim itself is still perfectly round.
I only posted the pic of the 20incher to show i can lace a wheel semi compentently to avoid patronishing tones.


I half missed the bad angle, because every single 26" 1000w wheel is laced exactly the same, and as somewhat proven by the grin spoke calculator, its impossible to get a good spoke angle and have spokes cross laced.

thanks for the help papasteve, as you can tell, im torn between radial n cross.....as everyone/internet says radial is "terrible" and to avoid it.
I half think most people who had a bad experience with radial.....didn't check spoke tightness after each ride for the first few weeks of riding on new spokes.

Changing/drilling/filing the spoke hole angle on a "naked" rim will still end up with the same problem somewhat.... the spoke will go through nicer but the nipple flange will still not sit evenly on the rim hole edge.....again causing uneven stress on one side of the rim holes.
A larger hole in a double skin rim with double skinned eyelets.....may or may not be stronger (depends what type of strength you mean).....as each eyelet joins the outer skin to the inner for extra overall reinforcement of the rim.
seeing as the strength failure in my current (cheap poo chinese) rim was the eyelet holes and not a malformed "doritoed rim"
i could extrapolate that a resonable quality rim from a reputable brand should be made of better material and be able to cope with larger spoke holes drilled for steel eyelets.

i really could do with a "better design rim" where each spoke hole has been pressed into the right shape/angle (like a motorbike wheel) see pic
View attachment 331449
dont suppose they do this for bicycle rims?

seems like short of finding the magical "above pictured rim" anything i do choose will end up being a compromise in one area or another

 

[FMB42]

Im not sure you read/understood properly.....I have both a 20" wheel bmx ebike and a bigger 26" wheel ebike. both with the same size/power hub motor and 1500w controller.
ive only just relaced the 20" after it being OOA for the past yearish (dented rim lip from flatish tyre+rough ground, not bad spoke holes).
the old 20" rim itself is still perfectly round.
I only posted the pic of the 20incher to show i can lace a wheel semi compentently to avoid patronishing tones.


I half missed the bad angle, because every single 26" 1000w wheel is laced exactly the same, and as somewhat proven by the grin spoke calculator, its impossible to get a good spoke angle and have spokes cross laced.

thanks for the help papasteve, as you can tell, im torn between radial n cross.....as everyone/internet says radial is "terrible" and to avoid it.
I half think most people who had a bad experience with radial.....didn't check spoke tightness after each ride for the first few weeks of riding on new spokes.

Changing/drilling/filing the spoke hole angle on a "naked" rim will still end up with the same problem somewhat.... the spoke will go through nicer but the nipple flange will still not sit evenly on the rim hole edge.....again causing uneven stress on one side of the rim holes.
A larger hole in a double skin rim with double skinned eyelets.....may or may not be stronger (depends what type of strength you mean).....as each eyelet joins the outer skin to the inner for extra overall reinforcement of the rim.
seeing as the strength failure in my current (cheap poo chinese) rim was the eyelet holes and not a malformed "doritoed rim"
i could extrapolate that a resonable quality rim from a reputable brand should be made of better material and be able to cope with larger spoke holes drilled for steel eyelets.

i really could do with a "better design rim" where each spoke hole has been pressed into the right shape/angle (like a motorbike wheel) see pic
View attachment 331449
dont suppose they do this for bicycle rims?

seems like short of finding the magical "above pictured rim" anything i do choose will end up being a compromise in one area or another

 

[FMB42]

The word is 'patronizing' not patronishing. Meanwhile, once again, your spoke angles were way off long before decided to 'wash your bike'. Meanwhile, I'd follow Chalo's advice by going with thinner high quality spokes and nipples.

 

[jimmyhackers]

if were going by "real english" and not the bastardised american version its actually patronising.

not sure what your problem is.....i'd rather not find out.

 

[E-HP]

Going from a 26" rim to a 20" 'BMX' rim is not, imo, a good idea (especailly one that is radial laced). I say this because most radial laced rims are for show only. Meanwhile, you are probably running spoke/nipples that are way too thick for your rim/hub combo (as Chalo often says). Meanwhile, the photos you posted very clearly indicate very bad spoke angles. You should have noticed this long before you 'decided to wash' your ebike.

I guess Chalo would disagree with you.

Extreme spoke angles with big hub motor wheelbuilds

I just built a 27.5" wheel with a voilamart motor and the angle between the spoke nipples and the spokes looks extremely dodgy and I'm concerned that it spokes will fail at that bend point. Is there any way to improve this with this build or my next one? Would nipple washers improve it? Thank...

endless-sphere.com

 

[jimmyhackers]

i wish id read that post from chalo from the begining too

"Radial lacing a hub motor is a good choice when the hub is large and the rim is small. In that case, there's no good way to cross-lace. Also, wind-up between hub and rim is negligible when the hub radius is large and spokes are short"

it would seem as long as my hubs motos lip/rim can handle the forces... it'll be ok. i will also take chalos advice on the 14g spokes though.....they're cheaper than 12g

 

[E-HP]

i wish id read that post from chalo from the begining too

"Radial lacing a hub motor is a good choice when the hub is large and the rim is small. In that case, there's no good way to cross-lace. Also, wind-up between hub and rim is negligible when the hub radius is large and spokes are short"

it would seem as long as my hubs motos lip/rim can handle the forces... it'll be ok. i will also take chalos advice on the 14g spokes though.....they're cheaper than 12g

It convinced me to try it, if I end up breaking more spokes and decide to relace. If I do, I think I landed on going ahead with drilling my flange to do the paired hole radial lacing. I still barely know what I'm doing, but at least the Grin spoke calculator has that option, so at least I'd have the spoke length covered.

 

[jimmyhackers]

https://www.youtube.com/@JefferyMcGehee/videos

Just found this chap on youtube, he's done stress simulations of radial and 3 cross spoke patterns, in both a wheel torque situation and a pothole situation. (4 short vids in total)

It's interesting to see how the two situations have thier pros and cons.
It's seems raidial puts the pothole stress into the hub and the 3cross into the top of the rim,
with the most spoke stress (red orange) appearing on the top spokes in 3 cross pattern.

Also it seems on the torque simulation that there is a lot of changing and uneven spoke forces with the 3 cross pattern. where as radial is all even.

Granted this is a simple simulation, and real world is somewhat different.
As said by papasteve, going cross pattern (with angle) will put more hub meat infront of the direction the spoke will pull, making it stronger hubwise. I dont think these simulations will show little nuances like that so well, but still quite interesting.

 

[PaPaSteve]

A very in-depth, expert analysis of an e-bike wheel rebuild by Bill Mould.

Technical Videos – Bill Mould Wheels

billmouldwheels.com

 

[jimmyhackers]

that explained a lot. thank you
from the spoke angle segment, i can now fully understand why my wheels poor spoke angle are creating a "2 points of contact vs 1" situation at the rim.
and why the 1 side is losing and cracking more : )

your rigth, a quick file/dremmel probably would of most likely prevented this problem.

seeing as this rims most definately on its way out, can anyone recommend some good strong 26" rims please?

i kinda want it wideish... its currently a 33mm outer width.... but i could go up to 50mm or 60mm. tyre is a 26x2.2.
would going to a wider rim make my tyre less rolly when leaning over? increase sidewall stability?

also....would a wider alternating spoke hole offset from the centre of the rim (made possible by a wider rim) increase or decrease wheel strength in any noticable/significant way?

 

[PaPaSteve]

JB Importers is a good info source.
Although ... since moving to Oregon I haven't found a bike shop who will order the products in a reasonable time frame.

 

[jimmyhackers]

ive found the same with my local bike shops in the UK..... apparently 3-4 weeks is a reasonable time to wait for a freewheel,
and people wonder why china is succeeding atm :s

also, bollocks to halfords (halfrauds).....knobber worker refused to redo a brake cable on my bike as it wasnt "road legal"
pointed out i can use my bike very legally on private property......still refused the provide the service.
then refused to sell me the brake line/cable to redo it myself at home.
i asked to speak to a manager....was left waiting at the front desk for 30 minutes.....then the store closed and the security guard triedto usher me out under threat of calling the police.

again F&*K HALFORDS!

 

[Chalo]

also, bollocks to halfords (halfrauds).....knobber worker refused to redo a brake cable on my bike as it wasnt "road legal"
pointed out i can use my bike very legally on private property......still refused the provide the service.
then refused to sell me the brake line/cable to redo it myself at home.
i asked to speak to a manager....was left waiting at the front desk for 30 minutes.....then the store closed and the security guard triedto usher me out under threat of calling the police.

Sounds like you have trouble hearing what other people are telling you. They're not obligated to do anything for you that they don't want to. Take the hint and go away.

 

[jimmyhackers]

dont be a tool chalo.

refusing to service a bike he wasnt comfortable with is fair enough, (i could accept that)
going that extra step and refusing to sell me a simple brake cable kit, so i could do it myself....was the knobber move (it was spiteful, vindictive and childish).

the final nail in the coffin for the whole store/franchise was the manager refusing to be a manager, just hid like a fliddy coward.

 

[E-HP]

going that extra step and refusing to sell me a simple brake cable kit, so i could do it myself....was the knobber move (it was spiteful, vindictive and childish).

Agreed, but probably a byproduct of desperation, too. The pandemic really accelerated the move from pedal bikes to ebikes, and I don't think most bicycle shops were prepared for that happening so quickly. Even the super pedal bike only shops around here have finally opened up to ebikes. The ones that keep fighting that change are hurting more and more, but still digging in. I think that for any bike shop to survive now, they need to hire at least one competent mechanic with ebike experience. That would help the shop, and customers needed service, while slowly educating the rest of the shop, and maybe keep it afloat.

 

[Chalo]

dont be a tool chalo.

refusing to service a bike he wasnt comfortable with is fair enough, (i could accept that)
going that extra step and refusing to sell me a simple brake cable kit, so i could do it myself....was the knobber move (it was spiteful, vindictive and childish).

I do it when someone comes in with a drippy, stinky gas motor bike with a loose floppy coaster brake and no front brake. I just want nothing at all to do with it, not even parts sales. I tell the cigarette-reeking alcoholic owner I don't want to be involved and I go on about my business.

 

[E-HP]

I tell the cigarette-reeking alcoholic owner I don't want to be involved and I go on about my business.

Hey now,...

 

[jimmyhackers]

you dont by any chance work at halfords chalo?

 

[offGridDownUnder]

knobber worker refused to redo a brake cable on my bike as it wasnt "road legal"

A business is private property, and may decline to provide a service. They are not slaves. Other people are free to live their own lives, their own way, for their own reasons.

Your remedy is to open your own bicycle business and do it your own way.

 

[RTIII]

The Bill Mould analysis was good but seriously flawed. Additionally, there are some misguided thoughts or insights in the thread as well.

I say that not as a person with substantial bike experience, but as an aerospace engineer and scientist, with substantial (compared with most people in these fields) "field experience", including personally working with an A&P to rebuild an aircraft from a damaged airframe shell to flyer.... Aircraft and bicycles have one critical thing in common (from an engineering point of view): both need to find "the sweet spot" between lightness vs having sufficient strength and durability, as well as cost to manufacture and cost of ownership. That said, I yield to Chalo's experience, which is directly applicable to bicycles as this is his primary profession, I believe, and I learned at least 5 years ago or longer to trust his recommendations.

That said, there are several dynamic effects to be considered and not just the stress on the spokes, and while Mould's analysis attempted to recognize that, his analysis was a bit misguided.

The reasons spokes are laced in non-radial ways are several. The primary ones of these include, first, strength of the RIM, which Mould's analysis ignored entirely. Secondly, the longer the spoke, the more stretch and therefore the more shock load it can handle. A third primary reason for cross lacing is reducing the load on any individual spoke's mounting points at both rim and hub, a fact Mould's analysis noted indirectly.

Another key issue with his analysis is that it was just straight on running; it gave NO insights into what happens when, say, you hit a curb head-on or at an angle or any of a number of critical, dynamic realities of a rim in service. These are hopefully somewhat rare events, but a wheel surviving them, even if bent, might WELL mean the survival of the rider! ...I've been hit by cars while riding at least three times I can recall in my life, including TWICE on my Raleigh e-bike conversion, and I can say that durability in a wheel is vital beyond many rider's awareness, and straight, radial lacing has to be THE worst there is on this point. And THIS is why it's primarily only used for show bikes, as the old-timers will tell you!

He, Mould, makes a good but, in my view, incomplete take on the thread issue: YES, the threads are a vulnerable spot, but the RIGHT solution, given the lack of "properly made" nipples that can support the spoke beyond the threads by being a net-fit on the spoke, is to have a spoke that's thin in the middle, which he correctly pointed out, but he didn't "bring it home" with a solid conclusion on the matter: Thicker ends, especially the threaded end, is "the" solution to the risk of breaking at a thread.

Personally, I wouldn't worry about that much because, were his analysis more complete, the math says even the smaller diameter spokes will have more than sufficient strength; a SINGLE SPOKE should be able to handle the entire load of rider AND the (non-collision) dynamic forces acting on it, it just has to be aligned "straight!" It's the BEND that's the issue, not the threads, and several replies have already pointed out simple ways of curing that problem.

An additional aspect that Mould misses is that the dynamics of rotation, important in both bikes and propeller driven aircraft, has a gyroscopic effect that, oddly, puts the apparent outside force acting upon the rotating body roughly (for our purposes) 90 degrees advanced (that is, in the direction of rotation) from the direction of rotation. This means that any effect of a spoke losing tension as it reaches the direction of gravity is an effective red-herring: Firstly, it's not harmful unless it's so loose that it can back out over time. And secondly, it's the load of the spokes ABOVE the hub that are taking the load of the weight! And see from his data how lightly loaded they are?

I also think he gets it wrong when he implies, but does not say, more tension on the spokes is better; I SERIOUSLY doubt it. Good to a point, SURE, but more is not always better! Chalo?! Care to chime in on that?

A few other points:

Sometimes in engineering, as just noted in the last bit I wrote above, less is more! One key example was learned by bicycle makers around the (PREVIOUS!) turn of the last century (about 1900) and got carried over as one of the foundational principals of aeronautical engineering: The tapered tube front fork was designed around then and it takes more load while being lighter! There are many other examples.

More surface area on load bearing surfaces - like the joints of spokes to rims - is always beneficial in terms of spreading the load, but it can sometimes have negative side-effects, so each engineering circumstance has to be considered individually. In this case, Chalo's decision, as noted above, was to add washers as the additional weight was negligible as compared to the benefit.

Happy Trails!

 

[jimmyhackers]

good read there. thanks for taking the time.

silly question....but are cross lacing benefits. reduced when the spokes do not contact each other on the "cross-over" points?

my 26" wheels current spokes do not contact each other at the "cross points"