Originally posted by xeu
A quick search on google should clear this up. Radial wheels connect the hub to the rim in a straight line, which makes the wheel stiffer but is also weaker and less efficiently transmits the twist of the hub out to the rim, so you better not have them on your back wheel.
Info from http://www.exploratorium.edu/cycling/wheel2.html
Originally posted by alex001
do radially spoked wheels make you more aero? are they stronger than conventially spoked wheels?
Originally posted by cachehiker
Radially they're stiffer and just as strong, but the difference is so slight I don't think you can actually feel it. Laterally, they flex more and I don't think they're as strong. Aerodynamically, I would think they're identical. However, they save you about a spoke's worth of spinning weight. I guess this would add up to about 0.05 mph for a 28/32 spoke wheel on the road.
Although I use a radially laced front wheel on the road, you won't see me using one on the trail. On fast corners, I feel the extra flex but it isn't particularly disturbing. A poorly built three-cross will still flex a lot more than a well built radial. I'm a strong climber too, so I'd rather not experiment with a radial non-drive rear either. I like having a few more pulling spokes.
On the mountain bike, I'm much happer using stiffer handlebars, stems, shocks, and wheels. I've started building my own wheels rather than succumb to the fascination of radial lacing and the possibility of having my front wheel wander. I'd rather stick to anal retentively well built wheels with 28/32 spokes in three-cross pattern and save the weight elsewhere.
Originally posted by lokstah
The discussion on radial spoking is interesting, but reading the original question, I wonder if alex001 wasn't looking for information about bladed spokes, and simply got the terminology bungled.
If so, the answer is probably just as debatable. I don't think anyone can doubt that a well-designed and well-aligned bladed spoke is more aero than a traditional spoke; I'm not sure what the data out there tells us about the strength or stiffness of bladed spokes, in general. Because there are fewer manufcaturers producing bladed spokes, it probably ends up being a matter of the manufactuer's process and materials, as well as how the design is implemented by the wheelmaker.
There are wheels out there with proprietary rim/bladed-spoke setups out there that carry reputations of being fragile, and just as many that are hailed as tough.
Originally posted by daveornee
If this about oval or flattened spokes, that is a different question.
According to Jobst Brandt in his book "the Bicycle Wheel":
"Twist continues to be a problem in use because the spokes are subjected to unscrewing forces from raod shock. With so little torsional strength they gradually turn crosswise to the wind and need to be continualy adjusted." That would be bad news as the desirable aerodynamic benefit would be lost. I built a set of bladed spoked wheels and didn't experience any turning, once I spoke aligned, tensioned, stress relieved, and tension balanced.
In know that my one set of wheels doesn't contain sufficient data to refute Jobst.
In the next paragraph Jobst continues:
"Both oval and flattened spokes are made from unbutted spoke blanks and have good or better tensile strength in the flattened part as the original spoke."
Originally posted by alex001
how about radially laced and bladed? thats what i meant
Originally posted by daveornee
Your assertion about radial spoking lateral stiffness is not correct.
You can read more on this at Sheldon Brown's Rinard page at URL:
http://sheldonbrown.com/rinard/wheel/index.htm
I would agree with you conclusion on 3 cross wheels.
Durability is the positive key differentiator.
Originally posted by cachehiker
How about if I restate the lateral stiffness issue this way:
Radial stiffness is better for radial lacing but torsional stiffness is greatly reduced. The additional strain on shorter, radial spokes is higher under lateral stress than it is on longer, three-cross spokes. More strain means more fatigue. Leaving the spokes a little loose to mitigate fatigue results in less lateral stiffness. Lacing them up a little too tight results in reduced durability.
Let's see if I have the rest of this argument, not entirely my own, right:
Stainless steel is ductile and does not exhibit a distinct yield point. When they're tightened beyond a certain threshold and put under a dynamic load, spokes will just keep stretching. Because of this and the strain issue, the line between too loose and too tight is much finer for radial laced wheels.
I'm just a programmer with a wheel fetish. Are there any mechanical or materials engineers out there with an opinion? Does Jobst (I need to get his book) offer any more insights?
As far as bladed spokes go, I'm sure they help but I don't know how much. Maybe I'll lace up a set next fall just to find out. Do you think the difference would be more or less than 0.1mph? Would I even notice?
Originally posted by daveornee
... Rinard's testing shows that lateral stiffness goes up when spoke tension goes down until the spokes are totally slack. ...
Originally posted by cachehiker
0.55 seconds per mile ~ 0.05 mph for me and the majority of my riding partners. About the same effect as losing a spoke's worth of spinning weight. Giving up beer, losing the extra five pounds that go with it, and trading in my sport touring frame for an actual racing frame would have a much more dramatic effect than using both radial lacing and aero spokes.
My last word. I promise.
Don't the downward pointing spokes go totally slack or very nearly so in the real world? Rinard does not appear to be applying a simultaneous radial load to simulate this in his measurements of lateral stiffness. With his fixture the upper spoke(s) near the point of load are resisting the rim deflection while the lower spoke(s) are still working to increase it. Although I think his method is valid for evaluating the relative lateral stiffness of similarly assembled wheels, I wonder if a good portion of the effect he is measuring is due to the rounded stress/strain curve of stainless steel and not the real world lateral stiffness of the wheel as spoke tension is increased. His curve, after all, is within 4% of flat for about six turns of tension. It actually corresponds pretty well with the elasticity of stainless steel from from zero tension to ~0.2% proof stress (~0.5mm of elongation). In any case, it does not correspond with my limited experience with spoke tension and lateral stiffness. One turn too tight or too loose may not affect lateral stiffness, but the effect of six turns would be profound.
We use essential cookies to make this site work, and optional cookies to enhance your experience.