Isn’t there also a difference in offset on 5.5" competition wheels so as to provide a substantially larger track on the rear?
And why were the larger/stronger competition wheels only proposed by Jaguar for rear wheels? Was it because the steering on front would have been too heavy with 5.5" comp wheels or because only the rear would require a wider footprint and/or suffer larger lateral forces?
My experience too, though I never found breakage after competitions (many fewer than you of course!) The Oil Leak tours – up to 3000 miles on road surfaces, some bad – inevitably end with three or four broken spokes. Of course when they are replaced, they are replaced with stainless steel!
Jerry
I’m no engineer (which I’m sure this post will confirm), but my vague recollection from college physics was that the longer the lever, the more torque is applied at the axis. Wouldn’t a longer spoke apply more torque at the hub end than a shorter one, all else being equal (which I say while acknowledging all else may not be equal)? I have this image in my head of asparagus stalks…the longer they get the easier they snap off…okay weird analogy, but that’s what came to mind.
Bill I think that the design of the wheel results in pulling only on the spokes - not bending them. The spokes are not fixed to the wheel or hub in such a way that they could be bent. The ends would just move in the holes they are threaded through.
All of the spokes are under tension (the wheel is said to be “hanging”) but nevertheless they collectively transmit torque. While a proper lever requires a fulcrum which is not present, there is a relation between length of spokes (or more precisely, the radius of the wheel) and torque transmission. A larger wheel, when powered from its hub, will deliver less torque to the road (i.e., to accelerate the car) than a smaller wheel–for the same gearing of course. A larger wheel will, when powered from near the tyre (i.e., braking), deliver more torque to the hub. IMHO–actually not even that–I’m relying on a book I have called Asparagus Tips.
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Interesting comments here, just to put my spoke in based on my experiences with wires over 60 years , I only had one car which broke its spokes on the hub and that was an SS one and a half litre pram top, little Y type Fords of the era were on the road in thousands in the fifties, and having a friend who was in the tyre, battery and exhaust business, saw only a few of these prewar side valvers came in with damaged spokes, but all still rolled…I would be there on a Saturday morning looking for any swopped tyres with enough tread on to fit on mine…forward to my present car which originally had the factory painted wires, how many times did I slide off road up kerbs and verges in the early seventies, never a buckle or lost spoke, forward to 1975, fitted the car with a set of Minilites…three years later high speed blow out on the front , Minilite buckled and distorted, …forward to the present, Dunlop chrome wires , stainless spokes…all good…my friends widow is still in business with her sons in law and grandchildren at the tyre and battery place, heaps of alloy wheels all destined for the smelter, Audi and BMW wheels being in the preponderance…damaged from kerbing and potholes…I see the wire wheels flex as an asset on Brit roads, they go through the mill but generally come through still round and true …