# advantage of driveside radial lacing?



## samh (May 5, 2004)

Like in Ksyriums. What are the benefits?


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## Zen Cyclery (Mar 10, 2009)

The only reason that you would do it would be to increase the bracing angle on drive side spokes. This is a good goal but radial drive side lacing is a bad idea for a number of reasons. 
1 If you use a conventional hub the amount of power that you are going to lose through the hub shell will be significant. 
2 If your designing your own hub then your going to have to make the hub shell significantly stronger thus adding weight.
3 No matter how strong you try and make that hub shell you will still get more flex than you would with conventional lacing.

The bottom line on a pattern like that is that Mavic is trying to look innovative. This same fake innovation drives their continued use of aluminum spokes in their wheels. That same "innovation" drove the design behind the RSYS The only hub that you would ever even consider doing a drive side radial pattern would be a Powertap. This is because it is driven from the non-drive side. Even on this hub I think it would be better to play it safe and do at least a 1x.


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## ssauter (Aug 1, 2007)

Zen Cyclery said:


> The only reason that you would do it would be to increase the bracing angle on drive side spokes. This is a good goal but radial drive side lacing is a bad idea for a number of reasons.
> 1 If you use a conventional hub the amount of power that you are going to lose through the hub shell will be significant.
> 2 If your designing your own hub then your going to have to make the hub shell significantly stronger thus adding weight.
> 3 No matter how strong you try and make that hub shell you will still get more flex than you would with conventional lacing.
> ...


While I am by no means an advocate of radial lacing on the drive side, I would say that a lot of modern hub shells are quite efficent at transfering torque to the non-drive flange. I tested a shimano fh-m570 a chris king iso, and an American Classic disc for efficency at transfering torque to the non-drive shell. I found that the shimano transfered close to 81% of drive torque to the non-drive. Chris king transfered 71% which surprised me. I expected the CK to be the most efficent. The American classic, as I am sure you could have guessed, did the worst with a torque transfer of only 37%. While I admit this is a very small representation of all the hubs out their, I think it shows that good torque transfer is definetly possible. I have a paper and data to show this as it is a lot to ask to just take my word for it. 

Steve


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## TedH (Jan 1, 1970)

Zen Cyclery said:


> That same "innovation" drove the design behind the RSYS The only hub that you would ever even consider doing a drive side radial pattern would be a Powertap. This is because it is driven from the non-drive side. Even on this hub I think it would be better to play it safe and do at least a 1x.


Powertap states on their site that their wheels must be built 2x DS in order for the warranty to be valid, and you see this build confirmed on places like Garmin's bikes/wheels. I find the PT and Zipp lacing interesting as Zipp's hubs are radial drive-side, which I found surprising, but they do send their PT wheels 2x. Would be interested to know if the poster who did research has torque transfer #'s on the new Zipp hubs.


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## Zen Cyclery (Mar 10, 2009)

PT does say that you must lace the drive side 2x but the drive side is not driving the hub. The drive force is transfered through the axel and then picked up by the non drive spokes. If you were to build a non-drive radial PT it would flex like crazy and possibly fail.


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## rruff (Feb 28, 2006)

samh said:


> Like in Ksyriums. What are the benefits?


Mavic did this because cross-lacing the fat aluminum spokes would have created a really bad DS bracing angle. They could get away with this on the R-Sys because the NDS spokes are designed to take compression.

A good reason not to do it is because forcing the lightly tensioned NDS spokes to take all the torque loads increases the chance of those spokes going slack... which weakens the wheel and leads to early spoke fatigue.

There is no problem with transfering torque through the hub shell... provided that the shell is strong enough to do it. Nothing is lost. 

Saris used to "require" lacing both sides of their hub 2x or 3x, but they have now changed to 2x on the NDS only. IMO the best lacing pattern for their hubs is 1x heads-in DS and 2x NDS because it improves the bracing angle and increases the NDS tension. Riders may need to get their derailleur hanger aligned though, because the clearance for the derailleur is sometimes tight.


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## kbiker3111 (Nov 7, 2006)

ssauter said:


> While I am by no means an advocate of radial lacing on the drive side, I would say that a lot of modern hub shells are quite efficent at transfering torque to the non-drive flange. I tested a shimano fh-m570 a chris king iso, and an American Classic disc for efficency at transfering torque to the non-drive shell. I found that the shimano transfered close to 81% of drive torque to the non-drive. Chris king transfered 71% which surprised me. I expected the CK to be the most efficent. The American classic, as I am sure you could have guessed, did the worst with a torque transfer of only 37%. While I admit this is a very small representation of all the hubs out their, I think it shows that good torque transfer is definetly possible. I have a paper and data to show this as it is a lot to ask to just take my word for it.
> 
> Steve


Can you describe/link to your testing procedure?


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## kbiker3111 (Nov 7, 2006)

Radial drive side spoke lacing reduces the deflection in the drive side spoke. Because the ds is the weak side, the idea is that most wheel failures start there. If you reduce the length of the spoke, the amount of deflection possible through that lspoke decreases. If the amount of overall deflection decreases, the wheel is stronger. Any extra deflection that occurs on the NDS is acceptable because of its increased bracing angle. 

Anyway, thats the way it was explained to me.


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## rruff (Feb 28, 2006)

kbiker3111 said:


> Anyway, thats the way it was explained to me.


I think the person who explained it to you does not know anything about the structural dynamics of a wheel.


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## Kerry Irons (Feb 25, 2002)

*Simple answer*



samh said:


> Like in Ksyriums. What are the benefits?


Marketing.


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## kbiker3111 (Nov 7, 2006)

rruff said:


> I think the person who explained it to you does not know anything about the structural dynamics of a wheel.


Maybe, I think it was more a theoretical approach.

e = (dL)/L e must remain constant.

So to reduce dL (spoke deflection), make L smaller (go from 3x to radial).


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## ssauter (Aug 1, 2007)

kbiker3111 said:


> Can you describe/link to your testing procedure?


Here is the data and paper. Unfortunatly the site I had the pictures set up on to help make sense of what I did isn't working. I will see if I can figure out how to get those up again. This test mostly concentrated on the effects of spoke lacing and hub wind-up. The last part of the paper touches on torque transfer through the hub shell.

Steve


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## rruff (Feb 28, 2006)

kbiker3111 said:


> So to reduce dL (spoke deflection), make L smaller (go from 3x to radial).


That much is true... but since the lateral stiffness imparted by the spokes goes up with the square of the bracing angle, it is actually the NDS that provides most of the stiffness. What radial lacing on the DS potentially does is optimize the bracing angle on that side... which allows you to have higher tension on the NDS... which is a good thing, because these spokes will now be more likely to go slack since they are taking all the torque loads. At any rate, you will not be able to offset the NDS as much as you could if *it* was the one that was radial laced... so the lateral stiffness will be less... so what was gained?

You can certainly make a decent wheel this way if the hub is designed for it, but the advantages are offset (more than offset IMO) by the disadvantages.


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## ssauter (Aug 1, 2007)

rruff said:


> That much is true... but since the lateral stiffness imparted by the spokes goes up with the square of the bracing angle, it is actually the NDS that provides most of the stiffness. What radial lacing on the DS potentially does is optimize the bracing angle on that side... which allows you to have higher tension on the NDS... which is a good thing, because these spokes will now be more likely to go slack since they are taking all the torque loads. At any rate, you will not be able to offset the NDS as much as you could if *it* was the one that was radial laced... so the lateral stiffness will be less... so what was gained?
> 
> You can certainly make a decent wheel this way if the hub is designed for it, but the advantages are offset (more than offset IMO) by the disadvantages.


I don't quite understand what you mean when you say, "At any rate, you will not be able to offset the NDS as much as you could if *it* was the one that was radial laced... so the lateral stiffness will be less... so what was gained?" Are you saying that you can get better lateral stiffness if you radial lace the non-drive instead of the drive?

steve


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## eddie m (Jul 6, 2002)

I've read through this thread (and others) and it occurs to me that every amateur wheelbuilder with a keyboard has an opinion that some exotic design or other is perfect, but the trained engineers who build wheels (Jobst Brandt, Roger Musson) think that 32 or 36 spoke 3X wheels work as well or better than any other design. I was tempted to correct all the technical errors here, but I decided that there were too many. 

em, P.E.


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## rruff (Feb 28, 2006)

ssauter said:


> Are you saying that you can get better lateral stiffness if you radial lace the non-drive instead of the drive?


Yes, if you go to the limit of where spokes are about to go slack but don't exceed it. If the NDS is the only side that that is taking torque loads, then you need to reduce the bracing angle or offset (which increases the tension) to keep them from going slack. If they are radial laced then they won't be subject to torque loads at all, so you can increase the bracing angle (which reduces the tension). The higher bracing angle on the NDS improves lateral stiffness.

BTW, tension has no effect on wheel stiffness unless the spokes go slack.


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