Spoke gauge, and other wheel building nonsense

[johnrobholmes]

After fighting a wheel that was china built and realizing that the 12ga spokes were the worst idea ever, I decided to start a thread regarding the various wheel builds that our E-bike and E-mutt builds require. I spent about an hour just trying to fix the damn wheel, and I could never get the spokes tight enough for proper stiffness. In fact, if I had kept wrenching on the spokes to get the tension up proper, I would have ruined the rim. For this reason, I can wholeheartedly agree with the sentiments that Chalo had repeated here many times- 12ga (2.6mm) spokes suck for using with bicycle rims! I should have just relaced the wheel with something proper. My time would have been far better spent.

Now, from experience I do know that 14ga spokes work for the vast majority of people on an ebike. The two issues are the hub spoke hole size and the insertion angle at the rim. With the oversized spoke holes the spoke tends to fail at the J bend more often from repeated flexing. The most ridiculous example is Xlyte x5 hubs, with a spoke hole big enough to pass an 11ga spoke (3mm+), maybe even a 10ga. Furthermore, with the increased flange width on hub motors, more stress is put on the head of the spoke instead of the bend. There really aren't many ways around this, except for not using a hub motor in the first place or using a motorcycle or scooter type rim to accommodate 12 and 11ga spokes.

The second issue is that the large diameter of hub makes for horrible spoke insertion angles at the rim. Except for using a good nipple like the Sapim Polyax, I have no clue as to a good way to solve this with standard bicycle rims. Motorbike and scooter rims have angled holes, so this gets around the problem while creating other problems for spoke and nipple size. Any thoughts?

What I am thinking is that single or double butted spokes may be the best compromise for the main spoke VS rim issue. A spoke with a 12ga head and 13ga nipple may have enough flex to allow for proper spoke tension without destroying normal bicycle rims, and still may fit into a normal rim. Not sure about the typical 13ga nipple diameter, maybe it won't fit in a standard rim. If this is the case, a 12/13/14 could be used, or even a 13/14. Heck, anything would be better than the shit I am dealing with on these china built wheels. It makes me glad I don't have to deal with the china built wheels often.

Any thoughts from the community at large?

 

[Ypedal]

I made a video about this.. does not cover it all by any means.. but some stuff.

http://www.youtube.com/watch?v=7-QZazAY0cc

[youtube]7-QZazAY0cc[/youtube]

 

[jag]

I built my BMC V2 into a sunrhyno EQ31 using butted 13/14ga spokes from ebikes.ca. As usually Sheldon Brown was my guide:
http://www.sheldonbrown.com/wheelbuild.htm

After fighting a wheel that was china built and realizing that the 12ga spokes were the worst idea ever,

Sheldon explains the gauge thing well. The elasticity in good thinner spokes makes the wheel stronger. Thicker gauge spokes can make it weaker, unless the rim itself is very rigid and strong.

With the oversized spoke holes the spoke tends to fail at the J bend more often from repeated flexing. The most ridiculous example is Xlyte x5 hubs, with a spoke hole big enough to pass an 11ga spoke (3mm+), maybe even a 10ga. Furthermore, with the increased flange width on hub motors, more stress is put on the head of the spoke instead of the bend.

Here Sheldon suggests that the spoke "J" should be alingning tight with the flange. This worked out well for my spokes and the inside-outside alternating orientation of the spokes. I guess I'll see if the wheel outlasts the hub motor or not.

For too big spoke holes maybe this solution with washers could work. It of course assumes a spoke "J" that has room for both the washer and the thick hub motor flange.

The second issue is that the large diameter of hub makes for horrible spoke insertion angles at the rim. Except for using a good nipple like the Sapim Polyax, I have no clue as to a good way to solve this with standard bicycle rims. Motorbike and scooter rims have angled holes, so this gets around the problem while creating other problems for spoke and nipple size. Any thoughts?

What I am thinking is that single or double butted spokes may be the best compromise for the main spoke VS rim issue. A spoke with a 12ga head and 13ga nipple may have enough flex to allow for proper spoke tension without destroying normal bicycle rims, and still may fit into a normal rim. Not sure about the typical 13ga nipple diameter, maybe it won't fit in a standard rim. If this is the case, a 12/13/14 could be used, or even a 13/14. Heck, anything would be better than the shit I am dealing with on these china built wheels. It makes me glad I don't have to deal with the china built wheels often.

Any thoughts from the community at large?

ebikes.ca sells 13/14. The ones I used seem plenty strong. For more spinginess I would have preffered 13/15/14, but AFAIK tripple butted cannot be had custom cut, and I didn't find the 191mm length I needed at DT-swiss.

In terms of cross lacing for the 205 9C and 173 BMC I use one cross. On second thought I would have gobe 2-cross on the BMC. Not because it is needed for strength (already 1-cross gives a slightly larger angle than 3-cross on a typical bike hub.), but because it moves the spoke crossover point slightly further outward. That would: 1/ move it past where the spoke is butted, 2/ make the bend at the cross slightly smaller. (remember it is inward-outward laced to create a firm contact point at the bend, but the bend is much larger compared to a normal bike wheel build.

 

[jag]

Afraid of taking on a wheelbuild? Fear Not!

Many seem to shy away from trying a wheel build, thinking it is only for the "professional". In reality the principles for building a good wheel are simple, and the task of doing it well is both rewarding and reinforces patience and attention to detail. My first wheelbuild I had to do a day before a race. I had cracked the rim. The mechanic had enough other wheels to finish to do mine on time, and instead suggested I'll put the new rim on myself in his shop so I could ask him if I ran into difficulties.

First myth buster: No special tools are needed to build a wheel. You can get it true and correctly dished using the bike frame.

What you need:
1: Parts: Rim, hubmotor, spokes and nipples.
2: A screwdriver and a wrench or spoke wrench. (ok the spoke wrench might be considered a special tool, but it is only $5-10)

Procedure:
1. Lace the wheel, that is insert the spokes and put the nipples on loosely. Sheldon has the details for how to get the pattern right: http://www.sheldonbrown.com/wheelbuild.htm
2. Turn the spokes to a known reference length, e.g. so the nipples align with the lowest thread turn on the spoke. The spokes should still be loose at this point, meaning if you strike them like a guitar string they don't vibrate, but just give a thud or plucking sound.
3. Pretension. Turn each spoke nipple 1 turn. Then test if they vibrate with a low tone. If not do all spokes one more turn. repeat until you get a sustained low tone.
4. True radially. Put the wheel in frame. Put a reference gauge as in the picture above. Rotate wheel. Any high spots? Likely yes. For each high spot, find a spoke nearby that has the lowest tension, that is lowest tone. Tighten it 1/2 or 1 turn. The tone should now be more similar or same as the others. Rotate wheel and repeat until height of wheel is even as well as you can see (within within 1mm or better)
5. True laterally. Now focus on the side to side movement. Rotate and find the largest wobble. Now we want to move the wheel sideways, without changing height. Therefore find high tone spokes on the side the wheel wobbles towards. Loosen one or two 1/2 to 1 turn. Then find low tone spokes on the other side and tighten these.

Now the wheel is true, but it may not stay true. You can settle the spokes, by using your hands to pull and squeze pairs or groups so to tension and release tension repeatedly. You can also just ride on the wheel a few days. It may then go a bit out of true. Repeat step 4 and 5 after this and then it should stay true. Some wheels stay true after the first tensioning, some like my 9C needed re-truing 2-3 times.

 

[John in CR]

Can you wheel wizards do a tutorial about converting one to a spoked motorcycle wheel? With all the flats and spoke problems I read about guys having with bike wheels, it's gotta be a better solution. I've got em on my motor wheels, and would love to go moto wheel on the fronts too. I like the beefy look of fatty tires as well, but that stuff just isn't available down here, and moto stuff is dirt cheap. I've even got a 16" Pirelli knock-off and rim ready to go, but the LBS's say it won't work on a bike hub, and the moto shops insist on a moto hub. I say bollucks, not enough flange holes could fail at once to be catastrophic that wouldn't be even more likely with a bike wheel.

 

[jag]

Can you wheel wizards do a tutorial about converting one to a spoked motorcycle wheel? With all the flats and spoke problems I read about guys having with bike wheels, it's gotta be a better solution. I've even got a 16" Pirelli knock-off and rim ready to go, but the LBS's say it won't work on a bike hub, and the moto shops insist on a moto hub. I say bollucks, not enough flange holes could fail at once to be catastrophic that wouldn't be even more likely with a bike wheel.

The "won't work" sounds like the usual BS you get when a store clerk doesn't wont to bother to think about your non-standard request. "Not an ideal combination" would be a better response if followed by a good motivation.

To try anyway, use a spoke calculator like Justin's on the ebikes.ca. The parameter ERD you need to put in is the "Effective Rim Diametre" that is the diametre the spoke sees from centre of the wheel to the surface where tyhe spoke rests on the inside. It might be stamped on the rim. Otherwise on a single wall rim measure the circumference inside the rim and divide by pi. On a double wall rim, measure the inside diametre, then measure the material thickness through a spoke hole using a caliper. Add 2x material thickness + rim inside diam = ERD

Hole size mismatch is likely a challenge. Drilling out the hub flange for bigger spokes is one obvious solution, but as mentioned above, thicker spokes do not necessarily equal a stronger wheel. To fit thinner spokes and nipples I was thinking it might be possible to put rivets in the motorcycle rim. Pop rivets could be tried by just poking out the centre part after riveting.

Surely such a wheel can be built and tried. How much stronger is a bike wheel with a MC rim, if at all? I don't know.

 

[Ypedal]

Problem with thick gauge spokes, 1 is that they don't flex much at all so anything other than single cross is almost impossible... and 2 they need a rim that can support high tension so only good quality double walled rims need apply.. good bicycle rims with eyelets are impossible to find for 10 gauge or similar spokes. unless you remove the eyelets ( good luck with that.. )

Motorcycle rims = Disk brakes unless you mod the bicycle components with a welder.

 

[liveforphysics]

If the spokes can't be stretched, the wheel is doomed. The big spokes can't be stretched due to limitations of the rim strength. This means it can never properly distribute loads, and the rim is a fail.

 

[amberwolf]

I guess that explains the ease with which my Fusin's rim was bent sideways just by scrubbing the tire perpendicular to the direction of travel, when I skidded in gravel a few months back. Even with the spokes all tensioned as tightly as possible, it still wasn't strong enough to resist this; they're (I think) 12G. Maybe 13, but I think 12; cant' recall for sure.

I am thinking that when I replace the rim on this with one off some other bike wheel I have (unfortunatley all singlewall cheapies) maybe I can find some regular 14G or 15G spokes on a smaller wheel that are the right length to still lace the Fusin into the new rim, so I don't have to use the thicker spokes. I'll have to measure the Fusin's spokes and see what length they are, to compare with what I have around here.

 

[jag]

Why spokes are alternating fashing on the inside and outside of the hub flange.

1/ "Run of the mill" wheels are often laced with all spokes running up the inside of the hub flange.

2/ Stronger wheels are laced in and alternating fashon every second spoke is on the inside, every other on the outside of the hub flange as in this picture from Ilya's web site.

Now it took me a while to realize the genious in this. One reason that spokes break that is often stated is the repeated tensioning and relaxation during biking. When the hub motor or your legs put power to the wheel then the leading spokes tension and the trailing ones relax. When braking with a disc brake the opposite happens.
Now if the relaxation is so great that the tension goes to zero, then apparently spokes will break quickly.

So why does the alternating pattern help here?
Now if we first consider regular lacing as in 1/. If tension unloaded is say 100N (=20lbs. Arbitrary value picked just for illustration). Unloaded both leading and trailing spokes have this tension. Now when loading the wheel toisonally either forward or backward one set of spokes will tension and the other relax. If we load the leading spokes to 200N then the trailing relax to 0 N and we have a problem. What to do? Well we can tension the spokes to say 200N. Then we can load more w/o problems. But we cannot keep tensioning spokes arbitrary. They will break. Particularly in a rear wheel build there is a delicate balance between drive side (right side where the freewheel is) and left side. Because the wheel is usually dished, the drive side spokes are often 2-4times as tense as the other side. We cannot get the left side tense enough w/o overtension the drive side.

So what is the genius in the alternation lacing? The spokes come up on alternating sides of the hub flange, then they are bent around each other the other way, so a bend is created at the point of crossing. At first I thought this seemed like a bad idea (bending the spoke could make it break). Now think of a spoke more like a string. Bending it is not such a big deal. (it is bent into a J at the hub and a bit at the rim also). However by bending the spokes around each other, when the leading spokes tighten, they transfer part of that tension to the trailing spokes and vice versa. (when say the leading spoke straightens from the tension, the trailing will bend more from the pressure from the leading spoke and part of the tension will be transferred.) Eureka!!! Now we balance the load on the spokes better and can apply much more driving or braking force without completely relaxing one set of spokes.

Looking carefully in the picture you might be able to see the bend. (it is easier to see in reality).

The mathematically inclined can try to analyse the exact relationship between leading and trailing spoke bending and the resulting tension. My guess is that initially (for an infinitesimal load increase) the transfer is ideal (ie maintains even tension) then as absolute leading spoke tension goes up the transfer force goes down, to a point when the leading spokes are straight and no more force can be transferred.

 

[amberwolf]

Perhaps this is why the 2-cross is typically better than 1-cross or radial pattern for wheel strength? I had not thought about that but it makes sense.

 

[jag]

Perhaps this is why the 2-cross is typically better than 1-cross or radial pattern for wheel strength? I had not thought about that but it makes sense.

In the alternating pattern build, the spokes are only wrapped around each other at the last cross, so there is only one contact point, whether 1, 2 or 3 cross. 2 cross moves the contact point outward a bit.

 

[Ypedal]

After alot of pondering, i think i prefer not having the spokes touch at the crosses, it's only going to cause friction and eventual spoke breakage at the intersections.

With a very small diameter hub ( on a weight weenie bicycle ) and thin flexy spokes, maybe nto such a big deal but with a hub motor's larger diameter, and thick spokes, having them not touch eachother is better imo.

 

[dumbass]

Two year ago i had a local bike shop rebuild a r to install a Nuvinci CVS hub. I even gave them the Nuvinci manual because to me (a complete dumbass on wheel building) there were some minor differences. First off the manual said to use a single cross on a 26" wheel and to thread the hub with all spoke heads on one side. When I picked up the rim they had built it with a double or triple cross. I honestly can't remember anymore but the spokes were on a 45% angle and at the rim they were bent a good 30%. We all know why they did this...The Nuvinci has a large dia simular to a hub motor and they didn't have the correct size spokes in stock. So they used what they had that would fit on a double cross. I refused to except the wheel and they agreed to respoke it. I told them this time read the damn manual first because there were some other strange requirements. They had to order a box of spokes which were special so I paid for the box or 75 spokes ($75 for the box) so I have a lot of spares. This time they built it with a single cross but they didn't thread it with all spoke heads on one side as the manual said. I questioned this and they explained that they say that in the manual and actually started doing it that way but decided to redo it alternating the heads as normal. I commented that the spokes were bending at the cross and I didn't like that. The guy that built the wheel said esplained that it adds strength to the wheel. He said that he builds all his racing wheels this way to reduce the side flexing in curves. Because I was still bitching they gave me a written 1 year waranty on the wheel for broken spokes. It's been 2 years and I haven't broken any spokes yet but if I do I still have the remaining 39 spares. So I guess there is something to say for the bent spoke idea.

Bob

 

[Drunkskunk]

Having the spokes touch were they cross gives the wheel more striength. Generaly crossing spokes are a leading and trailing spoke. by crossing, the spoke with the most tension is able to transfer some of that tension to the other spoke, increasing it's effective striength. It also helps soften the ride as a wheel laced like that will have more flex.

True, it will wear out faster in theory, but I've gone 10s of thousands of miles on roadbike wheels and not broken one due to rubbing. the amount of movement to cause wear is next to nothing.

Good quality 14 guage spoke hold up to DH offroad punishment, flying down mountian trails at 60+mph over logs, rocks, and roots. IMHO, if you can break a quality 14 guage spoke propperly laced, you need a motorcycle wheel.

Its either a #8 or #10 washer, can't remember the size right now, but it fits perfect on a 14g nipple and lets you use them on a rim drilled for 12g spokes. I prefer using brass washers as they conform to the rim and nipple's shape better. The also add some striength to normal rims by spreadung out the nipple's contact patch, and reduce the chance of cracking the rim.

 

[amberwolf]

After alot of pondering, i think i prefer not having the spokes touch at the crosses, it's only going to cause friction and eventual spoke breakage at the intersections.

FWIW, out of all the bikes I've ever had, regardless of abuse, neglect, etc, I've only ever broken spokes at the flange. Never at a cross.

 

[johnrobholmes]

In the alternating pattern build, the spokes are only wrapped around each other at the last cross, so there is only one contact point, whether 1, 2 or 3 cross. 2 cross moves the contact point outward a bit.

Unless it is laced for multiple contacts, generally called a race lace. More points of spoke to spoke contact increases the length of spoke between the hub and rim, thereby giving a bit more flex to the wheel. Not always good, but can be useful sometimes.



On 14ga spokes, I like at least one point of spoke to spoke contact. It isn't needed with 11ga spokes and thicker, and makes tensioning such a wheel very time consuming and friction prone. Unless dishing or the lace requires non-alternating spoke directions, I always lace alternating.


Never broken a spoke at the cross either, it just isn't likely.