Definitely not after any sort of "How to..."! I just started to get curious about whether contemporary wheel builders see any need to build disc and non disc wheels differently. I appreciate that minor changes in spoke length and dishing might be imposed by changing geometry, but would different spokes, tension, lacing patterns etc. be required?
(Copy of Mr Brandts book on order )
Trying to retain enough fitness to grow old disgracefully... That hasn't changed!
On the leaflet that comes with the hub it explains how you should put your leading and trailing spokes, the head-in or head-out being the difference.
In my case the wheels are fitted with ordinary rims and will be used with or without disc brakes, I have still laced them disc-style as that is probably where the forces will be greatest.
beardy wrote:On the leaflet that comes with the hub it explains how you should put your leading and trailing spokes, the head-in or head-out being the difference.
In my case the wheels are fitted with ordinary rims and will be used with or without disc brakes, I have still laced them disc-style as that is probably where the forces will be greatest.
I haven't seen any guidelines with hubs to be honest. Hope 3 and Novatec to name a couple.
I add a little more tension and no radial lacing. I avoid rims that are too light weight. Nothing else is different.
well disc hubs tend to have larger flanges and fatter barrels (to share the torque between the flanges) so I suspect that hub designers do worry about the brake torque wrecking the wheels.
At best the brake torque is shared between just half the spokes where they enter the rim. If the hub barrel is small and the hub flanges are large then it is just 1/4 of the spokes that take the brake torque. Despite this it is still the DS spokes that crack the rim in rear wheels and it isn't clear that the brake torque contributes much to this.
So the conclusion I have come to is that because brake loads are intermittent and normally form just a small part of the overall duty cycle, most wheels are still most likely to fail via fatigue and/or SCC (which are the normal design constraints), rather than instant structural collapse.
However if you went too low on spoke count or tried to use a very light rim, I think that you would risk the wheel failing through overload, and the brake torque would of course add to the other stresses.
Disc brake advocates have long touted the idea that we would be able to use much lighter rims once they were freed from their tiresome braking duties. Well, not so far, not really. Aluminium rims are already about as light as they can be and carbon ones are still too pricey for something you might fold up in your first ride.
Brucey wrote:well disc hubs tend to have larger flanges and fatter barrels (to share the torque between the flanges) so I suspect that hub designers do worry about the brake torque wrecking the wheels.
At best the brake torque is shared between just half the spokes where they enter the rim. If the hub barrel is small and the hub flanges are large then it is just 1/4 of the spokes that take the brake torque. Despite this it is still the DS spokes that crack the rim in rear wheels and it isn't clear that the brake torque contributes much to this.
So the conclusion I have come to is that because brake loads are intermittent and normally form just a small part of the overall duty cycle, most wheels are still most likely to fail via fatigue and/or SCC (which are the normal design constraints), rather than instant structural collapse.
However if you went too low on spoke count or tried to use a very light rim, I think that you would risk the wheel failing through overload, and the brake torque would of course add to the other stresses.
Disc brake advocates have long touted the idea that we would be able to use much lighter rims once they were freed from their tiresome braking duties. Well, not so far, not really. Aluminium rims are already about as light as they can be and carbon ones are still too pricey for something you might fold up in your first ride.
cheers
I guess the hub manufacturer will control you wont go too low on the spoke count.
)
