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Today's wheelbuilding question : about radial non-drive(20 posts)

Today's wheelbuilding question : about radial non-drivePeterRider
Dec 3, 2003 11:54 PM
Is radial non-drive a good or a bad thing ?
- Sheldon Brown says that at first, he was completely against radial, front as well as rear non-drive. But then, he noticed that spokes break most of the time because of too little tension, so radial non-drive should be good since you have higher spoke tension
- recently, I've read that radial non-drive causes 30% or 40% (don't remember) more stress in the spokes. Is this stress only fatigue, or does it help transmission, or has nothing been proved ?

I'm an engineer, but no mechanical engineer, so any information is welcome.

re: Today's wheelbuilding question : about radial non-drivelyleseven
Dec 4, 2003 8:06 AM
I think you mean the non-drive side has less spoke tension. I have a set of radial non-drive side wheels and have had no problems with them in 1500 miles.
re: Today's wheelbuilding question : about radial non-driveEric_H
Dec 4, 2003 11:33 AM
The advantage to radial NDS spoking is that the spokes are all oriented in the same direction. In a 3x wheel, the "trailing" spokes suffer from more changes in tension under pedaling loads and riding loads. The spokes don't break from too little tension, but instead from repeated loading and unloading. In a radial spoke NDS, the spokes are not as affected by drivetrain transmission torque, and are only loaded/unloaded as they pass through the bottom of the rotation of the wheel.

Personally, all my wheels are 3x. I have started building the NDS with Revolution spokes 14/17/14 g, with the DS 14/15/14 g. The relative elasticity of the thin and light Revolutions minimizes the loading and unloading effect and the effective tension is higher in the NDS spokes. You can hear this by plucking a wheel with Revs on the NDS and then plucking a wheel with the same gauge spokes on both sides.
A Good thingbimini
Dec 4, 2003 11:46 AM
I have had problems with the Non drive spokes being too loose on 3x wheels when the same spokes are used for the Drive & non-drive side. Too get enough tension in the Non drive spokes to stay tight the Drive side has to be over tightened.

I'm a little bit concerned about the radial layout if you are a heavy rider or hard sprinter. I have a radial front on a 32 spoke Open Pro setup and am not happy with it. I like to get up over the bars when sprinting and the front feels wishy washy (unstable) compared to my other set of 32 spoke OPs with 3x layout.

The 14/15/14 drive side and 14/17/14 non drive side all 3x mentioned above sounds like the best solution for me and is what my next build will be. I may even tie and solder the set up and use them for my sprinting wheels for next years oval series.
Am I missing somethig here?B2
Dec 4, 2003 12:15 PM
I'm having a hard time trying to understand how spoke pattern and/or spoke size would have any effect on spoke tensions (given no change in the number spokes on L vs R)?

It seems to me that the maximum (reasonable) tension that the rim can take at each individual spoke is the controlling factor and the size or shape of the spoke wouldn't effect this value. The non-drive side will obviously have a lesser tension, but the necessary tension to achieve the correct dish should relate directly to the actual spoke tension on the drive side. How would the lacing pattern or spoke size/shape effect the amount of tension in the spoke? Wouldn't the tension be same regardless of whether or not you had 10g spokes or 30ga spokes?

I do understand that the lacing pattern will effect the way the tension in a spoke changes while riding, but it seems like people are talking about building with different tensions based of spoke size and/or lacing considerations.

I'm missing the same thing...TFerguson
Dec 4, 2003 2:56 PM
The tension per spoke is the amount required to center the wheel.

I understand the benefit of the DB spoke, the thinner the better (to a point), but that is true no matter how many, what size or what cross pattern.

All the spoke heads are out.Spoke Wrench
Dec 4, 2003 3:50 PM
With a radial pattern, you can have all of the spoke heads out. This results in a spoke triangle that is closer to symetrical and, consequently, requires higher tension on the non-drive side to center the rim.
Ahhh I see!B2
Dec 4, 2003 4:17 PM
By changing the lacing to radial, you're actually changing the position of the spoke. This of course changes the tension required to accomplish the dish.

So that means a lower bracing angle?Kerry Irons
Dec 4, 2003 4:51 PM
Building with all heads out does require a slight increase in spoke tension to balance the forces from the drive side spokes, but at the cost of reducing the bracing angle of the wheel, and therefore perhaps reducing lateral stiffness a bit. Whether this is significant either in terms of stiffness or balancing spoke tension, I do not know.
Not really.Spoke Wrench
Dec 5, 2003 3:49 PM
The bracing angle on the left side is still going to be significantly greater than on the drive side.
Well, a bit?Kerry Irons
Dec 7, 2003 6:54 PM
My point was a "slight" reduction since the spoke is coming from the inside of the flange rather than from the outside of the flange. Probably not enough to affect lateral stiffness, but probably not really any reason to do it (as opposed to conventional build).
My lousy explanationEric_H
Dec 4, 2003 4:05 PM
I did not explain the advantage to using the Revolution spokes on the NDS very well in my above posting, and I'm not sure I'll do much better here.

You are correct, the tension in the NDS is determined by the amount of dish. However, the thinner sections of the Revolutions will allow for a higher relative tension in the spoke. The spoke will be putting the same load on the rim on the hub, whether it is a Revolution or straight 14g, but the tension in the spoke will be different. It is comparable to suspending a weight by a piece of steel rod and then by a string (an extreme example). The load is the same, however the string is under much more tension to support the load than the steel rod. The other benefit of the Revolution spokes is that their elasticity spreads the load over more spokes as an area of the rim is unloaded during riding (I'm stealing this directly from Brandt's book).
Just a little...Alexx
Dec 4, 2003 4:41 PM
Yes, the tension ould be the same, but the stress (being a function of the cross-sectional area) won't.

BUT....there are many other factors involved, such as cyclical fatigue. That's the main reason for going semi-radial. Heavy sprinters cause heavy cyclical fatigue on HALF of the non-drive spokes (namely, the 'leading' spokes), wheras in a semi-radial, ALL the non-drive spokes recieve HALF of that same amount of load. End result: fewer fatigue failures.

Oh, there's soooo much more I can talk about on this subject! Got a few hours?
Can sprinting really be a factor?...TFerguson
Dec 4, 2003 5:08 PM
One race sprint/week, a couple dozen in practice. That's maybe 15 minutes of loading/unloading compared to the well over 15 hours (20? 30? a lot more if you like Lance) of ride time. Like a lot of what we discuss here, doesn't seem significant.

But for the sake of discussion, since the radial NDS spokes no longer resist wind up as well, aren't you risking an even greater fatigue on those poor DS leading spokes?

What about...divve
Dec 5, 2003 12:36 AM
...a cross-over where the trailing spokes bend or if you will tension the leading spokes due to pedaling forces? Would this sort of cancel out the tendency for the leading spokes to relax? See below image for what I mean:
check out Zinn's book...ukiahb
Dec 4, 2003 12:52 PM
his "Art of Road Bike Maintenance" book's wheel building chapter discusses this kind of wheel and has detailed instructions on how to build one.....
OK, thx for the arguments, but what about power transmission ?PeterRider
Dec 4, 2003 3:57 PM
is power transmission from you to the rim better with radial, 3x, or nobody knows ?

No difference.fallzboater
Dec 4, 2003 9:53 PM
Tangential spoking (spokes leave the hub tangent to the flange) results in the least "wind-up." But, even with wind-up, there's no lost energy between the hub and rim. So, one spoke pattern is not any more efficient than another (durability is another story). There's tons of marketing BS out there.

Also remember that pushing (leading) spokes contribute to driving the rim as much as pulling (trailing) spokes. You can push on a rope, as long as it's under tension.

OK, thx for the arguments, but what about power transmission ?tube_ee
Dec 4, 2003 11:30 PM
If you read Jobst's book, he clarifies this. Basically, radial spokes cannot transmit torque. What happens is, the hub winds up relative to the rim, at which point the spokes are no longer radial, and can transmit torque.

The closer the spokes are to being tangential to the hub, the more torque they can transimit. Rule of thumb I've seen said that 3x is tangential for 32 spokes, 3x or 4x for 36 (4x is ideal, but lacing is harder), 4x for 40, 5x for 48.

Get and read "The Bicycle Wheel". Since you're an engineer, the math is pretty sraightforward, and the concepts you learned in basic mechanics (and FE / PE exam study) should serve you well.

re: Today's wheelbuilding question : about radial non-driveMShaw
Dec 5, 2003 10:35 AM
The only wheel I've built radial non-drive was a CXP30 with 24 Ti spokes. I could feel a difference cornering left vs. right. It felt stiffer going one way, softer going the other. I don't remember which was which.

Great for triathletes 'cause they don't do anything BUT go straight. Bad for crit racers like me...

It could've been the radial. It could've been the Ti spokes. It could've been too few spokes. I don't know. I haven't laced anything radial NDS in a few years to confirm or deny the above observation.