Subject: Re: Radial lacing on drive side R Wheels Posted by: steve on August 07, 2006 at 20:02:25: In Reply to: Radial lacing on drive side R Wheels posted by Andy on August 03, 2006 at 13:21:52:

Message: >I've been having this debate in our shop about radial lacing on drive side of rear wheels, as some shimano wheels have become as well as some others. Is the greater torsional load in the pulling spokes (non drive in this case)or in the drive side of the wheel. Where is the greatest load on a 3x by 3x rear wheel then, if radial lacing does work with a strong enough hub to transfer the load to the non-drive side? Anybody have any crazy thoughts on wheel physics. To me radial lacing on the drive side just doesn't do it. I think that the higher torsional loads on a radial drive side wheel are going to be on the pulling spokes non drive. Radial lacing has no capability to prevent torsional movement. The key word here is radial, as soon as that spoke leaves a line that radiates directly out from the center of the hub they can now start to resist tortional movement because it can create torque. The question then becomes does a biker create anough force to rotate the hub to a degree that the drive side spokes can create a greater torque than the non-drive spokes to resist rotation. This can only be answered if the tortional stiffness of the hub is known. But if you do some simple trig you will find that if the hub rotates so that the spoke is at an angle of .1deg. with the imaginary center line that goes from the rim to the center of the hub and your spoke is at 1100n then the torque that is created per spoke is only about 1.92n were as a three cross on the non-drive side will have a spoke angle closer to 5 deg. which with an 800n spoke will create close to 68n of force. therefore the non-drive will take the majority of the tortional load assuming the hub is stiff enough. Now if we look at a wheel that is 3x drive and non-drive the majority of the tortional load will be taken up by the drive side. This is because the drive side has greater tension and since the drive and non-drive sides have the same spoke angle the torque produced by a drive side spoke is greater. One other thing to consider is the tortional stiffness of the hub body. I don't really know how to explain this except that as the drive flange rotates the hub body tries to rotate with it the non-drive spokes are the only thing stoping the body from rotating. Therefore if a hub body is stiffer it will be able to exert a greater force on the non-drive spokes per degree of rotation thus allowing those spokes to share some of the load being exerted by the rider. But since the non-drive spokes are at lower tension and because there will always be some twisting in the hub body the non-drive spokes will handle less torsional load than the drive side. I hope this makes some sense. If it doesn't, I will be more than happy to try and clarify anything that doesn't make sense.