Wheel lacing for left drive sprocket

I'm just testing my "Peltzer" clone, and wonder why my rear spokes all came loose after a few miles. The wheel is laced for right-hand drive, but the main source of power is the electric drive, which drives off the left side. Could this be the cause of my wheel coming apart, or did I maybe just do a sloppy job when I built it?

Anyway, for now I re-tightened all the spokes and trued the rim, and will do some more testing. But I'm really interested in some feedback on this.

Apart from this one glitch, the 80lb monster has bags of power and charges up my 25% grade driveway with no problem!

When you lace a wheel, you need to go over it again at least once to remove spoke twist or wind-up that wasn't relieved after the truing. As an ebike with motor, battery and person puts a lot more load on the rear wheel, the rim can flatten slightly at the contact point and allow the spoke to unwind itself. This causes the wheel to become loose. Double butted stainless spokes may show this problem more due to being more prone to twisting when truing but are better in the long run if you eliminate the wind-up. This is because they stretch more than a plain spoke when in the wheel, so have more ability to remain under tension when the rim deforms.
A plain rim is more prone to this problem as it will deform more than a double wall rim.
Make sure that there is not a huge difference in tensions between the spokes by plucking them and listening to the tone. There will always be more variation in tone around the rim join as this is rarely ever perfectly true and has a variation in strength because of the wire pins that are within the rim at the join.

A sublety:
If you look at the hub you'll see that there are inbound and outbound spokes at each hub flange. It is best to have inbound opposing inbound and have outbound spokes opposing outbound. The spoking should be as symetrical as possible. This helps reduce lateral movement of the rim when a torsional load is placed on the hub, making brake block rubbing less likely.

An extra sublety:
When drive is applied to the hub there are "pushing" and "pulling" spokes. It is always best to have the pulling spokes <[Edit: OOPS! Error! 'outbound' is wrong] ElectricEd> inbound. When a torsional load is applied to to the hub, outbound pulling spokes push sideways against the pushing spoke that they cross, moving the spoke plane away from the derailleur jockey. Depending on load, size of rim, lacing pattern and spoke tension, this can displace the spoke plane by as much as a millimetre. It doesn't seem like much, but would you really wouldn't want to reduce the clearance.

Its good to hear that you have gobs of climbing power too. My brother has a similar setup and can climb lamp posts with it. :wink:

HTH, Ed.

The spokes don't know which side the drive force is coming from. they get there power from the hub, and its transfered to the spokes uniformly regardless of which side the drive force originates.

But a normal wheel is built for 150 to 300 watts of human power and torque. when you strap a motor that can peak at 2000 watts or more to it, the end result is spokes being pushed far beyond what they were ment to do. wheels will come apart if not built with quality parts and maintained.

if all the spokes are loosening, it means: (A) that the wheel was pretty good, as the force was distributed evenly, and thus the spokes stretched evenly instead of breaking a few spokes, and (b) that the wheel just isn't up to the job of handling the stress on it.

One thing to consider here as well;

If this is truely a Peltzer clone, the sprocket is clamped to the spokes near the hub, not the hub itself. I know from his pics, it looks like it is bolted to the hub, but Eric Peltzer bolted the sprocket through the spokes with clamp plates.

That type of drive has issues because it is crushing the spokes together and the load is distributed in a manor noever intended by the spoke design.

Matt

Mods may want to move this to Non-hub section.

I'm guessing it self destructed because the spokes were way too loose when you built up teh wheel, I'd suggest try again but tighten it up a good bit more. If you "pling" it, like turning a nipple that turns by chunks, then the wheel should resonate a bit.

Ed said:

An extra sublety:
When drive is applied to the hub there are "pushing" and "pulling" spokes. It is always best to have the pulling spokes outbound.

Click to expand...

Wow ... ALL my wheels have the pushing spokes inbound. I built them all using the same book. I talked to a trusted bike shop person today and he suggests exacly what Ed suggests, but that it is not absolutely critical. He also asked me if I 'stepped' on the spokes after truing the wheel, and I admit I forgot to do that which is probaly why it came loose real quick. As Mathurin pointed out, they were not tightened enough to start with.

Drunkskunk said:

The spokes don't know which side the drive force is coming from. they get there power from the hub, and its transfered to the spokes uniformly regardless of which side the drive force originates.

Click to expand...

Doh ... I realized that shortly after I posted :lol:

recumpence said:

If this is truely a Peltzer clone, the sprocket is clamped to the spokes near the hub, not the hub itself.

Click to expand...

I used a Stanton Inc rear hub with a left hand freewheel sprocket with the gears cut off and a larger 36 tooth sprocket machined to fit, then brazed over the original, so I am driving from the hub, not the spokes. I wasn't happy with Eric's compromise: this way I can pedal without dragging the motor along.


Did a 12 mile ride this morning and all is behaving well. If the wheel stays tight, I'll wait a while before I re-lace it the proper way. Meanwhile, I need to get a proper disconnect on the battery before I have an accident.

Thankyou all for the excellent feedback!

Drunkskunk wrote:
The spokes don't know which side the drive force is coming from. they get there power from the hub, and its transfered to the spokes uniformly regardless of which side the drive force originates.

Click to expand...

Not so, there a several things going on.
In a standard bicycle rear hub when drive is applied there is a torsional twisting or wind-up of the hub. The non-drive side spokes may be exerting as little as 10% of what the drive side spokes do.

There is also a wind-on of the hub in relation to the rim. This means that the pulling spokes are under tension and the pushing spokes are having their tension reduced.

The bicycle wheel is a wonderful example of a 100 years+ development. The more you go into it, the more amazing it is. 8)

PeterJ said:
Wow ... ALL my wheels have the pushing spokes inbound.

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Hmm, looking at your close-up picture of the hub, I reckon that you have it exactly the way it should be. By "inbound" I mean that when you insert the spoke through the flange, it is being inserted from the outside toward the inner of the hub.
Your inward facing spokes are "pulling" and are laid over the outside of the last spoke that they cross. That is the best way to have it.
On looking at the way they cross, I don't think the tension is up to what it should be. The crossing spokes on your wheel have a smooth arc around each other. When I build a wheel, the tension is so that there is little of an arc, more of an angle. Double butted spokes show this effect more than plain spokes. Carefull though, if you go too tight, the wheel can snap into a pretzel shape.

ElectricEd said:

In a standard bicycle rear hub when drive is applied there is a torsional twisting or wind-up of the hub. The non-drive side spokes may be exerting as little as 10% of what the drive side spokes do.

Click to expand...

`
Can you site any documentation on this?

PeterJ, Thank you for posting the links about the Stanton hub and left-side freewheel. Its one thing to surf the net and think I found something that "might" work, its a completely different thing for me to read "This is what I bought, and this is how it worked for me".

Drunkskunk said:

ElectricEd said:

In a standard bicycle rear hub when drive is applied there is a torsional twisting or wind-up of the hub. The non-drive side spokes may be exerting as little as 10% of what the drive side spokes do.

Click to expand...

`
Can you site any documentation on this?

Click to expand...

The Bicycle Wheel. Jobst Brandt.
He did these tests on a special jig he had made up. I think it was a for a paper he was writing for the university that he was associated with.
I'll be able to post the edition, pages and ISBN later today when I get back home from work.

Back again.
I've searched everywhere but cannot find my copy of The Bicycle Wheel. I must have lent it some time in the past and it is now gracing the bookshelf of one of my irresponsible friends. :wink:
One place to get a lot of inforation ala Jobst Brandt is at Sheldon Brown's website: http://www.sheldonbrown.com/brandt/index.html
There is a lot of stuff there, much of which is covered in The Bicycle Wheel.
What I like about his publications is that his research has over the years been a myth buster for quite a few aspects of cycling mechanisms.
Well researched science is always better than blind faith. 8)

A thought on hub stress.

Because of the way a wheel is dished, the ds spokes get more stress then nds. You can feel this easely just by grabbing a wheel and feeling the spokes. I used to wonder why on high end wheels the nds is radial and the ds is crossed, I would have thought doing it the other way around would transfer stress on the less stressed nds spokes, and so make a wheel that lasts longer. It seems they don't do that because it fatigues hubs and tends to make them break. Using a beefier hub would add weight, but it seems it's less heavy to use crossed lacing on ds using brass nipples and sometimes beefier spokes, and on nds radial lacing with alu nipples and sometimes thinner spokes.

Your post prompted me to join this forum, which I had only ever lurked on before.

I like your left-side drive solution. My first e-bike used a RH/LH hub for two separate freewheeling drivetrains. I machined a 144 tooth #25 chain sprocket which I bolted to a 16T southpaw freewheel with special rings that encased the sprocket teeth. That mated to a 400W scooter motor for 12:1 reduction in a single stage.

PeterJ said:

I'm just testing my "Peltzer" clone, and wonder why my rear spokes all came loose after a few miles. The wheel is laced for right-hand drive, but the main source of power is the electric drive, which drives off the left side. Could this be the cause of my wheel coming apart, or did I maybe just do a sloppy job when I built it?

Click to expand...

The reason spokes come loose is because they were not tight enough to begin with. The wheel bears a load by allowing the rim to flex inward towards the hub a tiny bit, and the spokes must be stretched enough under tension to take up this rim flex without going slack.

A heavily loaded wheel, or one with an unusually flexible rim, or one with loose spokes, will slacken each spoke once per rotation as that part of the wheel bears weight. The incessant cycle of slackening and tightening causes the nipples gradually to back off. You can cure this by adding enough tension to the spokes that they don't slacken (best approach) or by applying a threadlocking compound to the spoke threads so they don't work loose (sometimes necessary but never ideal).

For what it's worth, butted spokes (thinner in the middle) or spokes that are thinner overall are less likely to slacken because they stretch more at any given tension, so they can take up heavier wheel loads without slackening. That's why it's a mistake, albeit a common one, to use extra-thick spokes for a heavy-duty wheel. 13ga, 12a, or thicker spokes are way more likely to make for a wheel that exhibits chronic spoke loosening.

From the look of your photos, you have either an Alex DM18 or a Sun AT18 rear rim. Either one of these should be able to withstand at least 100kg of tension per spoke, with the Alex being both stiffer and tolerant of higher tension. If that's not enough to keep the spokes from loosening, try threadlocker (linseed oil, Spoke Prep, or purple Loctite) or thinner gauge spokes.

On an unrelated note-- if your Staton hub is the kind with snap ring grooves machined into a 1/2" axle, be aware of two potential problems. The small axle shoulder can gouge your bike's dropouts, and the axle can break at a snap ring groove. Close-fitted hardened washers between the axle shoulder and the bike frame can address the first problem, but the only cure for the stress risers created by the snap ring grooves is to make another axle that doesn't have grooves.

Chalo

Mathurin said:

A thought on hub stress.

Because of the way a wheel is dished, the ds spokes get more stress then nds. You can feel this easely just by grabbing a wheel and feeling the spokes. I used to wonder why on high end wheels the nds is radial and the ds is crossed, I would have thought doing it the other way around would transfer stress on the less stressed nds spokes, and so make a wheel that lasts longer.

Click to expand...

Axle load on the wheel is borne by as few as one or two spokes at a time. Hub torque is shared to a greater or lesser degree by all the spokes in the wheel, so it does not affect spoke tension nearly as much. Except for radial and cross-one lacing, just about any wheel that can carry its load can also withstand any amount of torque we place on it.

Chalo

Mathurin said:

A thought on hub stress.

Because of the way a wheel is dished, the ds spokes get more stress then nds. You can feel this easely just by grabbing a wheel and feeling the spokes. I used to wonder why on high end wheels the nds is radial and the ds is crossed, I would have thought doing it the other way around would transfer stress on the less stressed nds spokes, and so make a wheel that lasts longer.

Click to expand...

Because of the torsional windup of the hub when drive is applied to the sprocket, up to 90% of the drive is applied to the ds spoles. Radial spoking provides no resistance to the wind-on of the hub in relation to the rim. Only the tension of the spokes resist this after a small amount of wind-on, placing enormous pressures on the nipple seats and hub flange, causing failure of the rim, or failure of the hub due to the tension being applied through the narrowest section of aluminium in the flange.
Crossed spoking (the more crosses the better) is not effected by this as there is minimal hub wind-on, the pull on the nipple seats is not amplified and the spoke tension is pulling through a larger section of aluminium in the flange.
With those high end wheels, crossed spoking in the ds will take nearly 100% of the drive, the torsional wind-up of the hub and zero drive effect of radial spoking will mean little going through to the nds.
With the suggestion of reversing this and having radial spoking on the ds, another aspect comes in. Ds spokes are tensioned to 2-3 times the tension of nds spokes.This problem got worse with the increasing cog count on clusters. Due to the fact that most drive will have to be transmitted through the hub to the crossed nds, there will be a lot of hub wind-on on the ds due to the radial spoking. This will definitely cause a failure of the ds hub flange or the nipples will pull through at the rim. It is only a matter time for what happens first.
Offset spoke holes in the rim help to alleviate the difference in tensions by making the inclining spoke planes closer to equilateral.

Mathurin said:

It seems they don't do that because it fatigues hubs and tends to make them break. Using a beefier hub would add weight, but it seems it's less heavy to use crossed lacing on ds using brass nipples and sometimes beefier spokes, and on nds radial lacing with alu nipples and sometimes thinner spokes.

Click to expand...

Radial spoking is largely a cosmetic thing. One argument is that a smaller frontal area is exposed because of it being shorter, causing less drag. This would probably be immeasurable though. I reckon most do it to be different and it looks neat. I did.
The fact that a 3 cross pattern is by far the most common used is no accident. For any given materials, it provides the most cost-effective strongest wheel possible. 4 cross is heavier, runs the risk of spokes interfering with each other at the flange and is harder to build. 2 cross may not be used because it runs closer to the edge of the envelope as does 1 cross and radial. These work in high end wheels because they are built with better materials.
Imagine trying to build a wheel with mild steel spokes in a pressed flange in a cheap rim and make a profit. You'd go for the cheapest, quickest, strongest method.

I run 2 cross and radial on the rear wheel and radial on the front wheel of my Audax bike. I find that I have to regularly re-true the front wheel and occassionally the rear. I don't think it's because of my lousy wheelbuilding skills but due to the inherent lack of strength with radial spoking. There is more unloading of the tension of the spoke from sharp bumps and even the slightest amount of spoke twist unable to be removed in truing can come out.

According to tests by Jobst Brandt (and in my own experience) the strongest, most resilient wheel has 3 cross laying, double-butted SS spokes in a dual wall rim with eyelets.
Note the "resilent". A deep V rim will be stronger, but is a damned uncomfortable thing to ride.