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spokes tend to fatigue much quicker on a rear wheel, mostly because that's the driving wheel, where the acceleration "happens" and it happens at the hub, where typically spokes fail. Front wheel spoke failures are much rarer, suggesting deceleration at the rim has very minor effects.
Fatigue is a function of both the number of cycles and the peak load. Drive side rear spokes get two load cycles for every revolution of the cranks, rotor side spokes get a load cycle from the braking torque once every time the brake is applied, a much smaller number in most cases.
While it would be a good idea to design drive side rears to operate under the fatigue limit for any sustainable torque input, there might be an argument for allowing total load under heavy braking to exceed the fatigue limit by a substantial margin since a fatigue life of 105 cycles could easily represent more than 100,000km on a road bike
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gbj_tester
Harder to say... however, spokes tend to fatigue much quicker on a rear wheel, mostly because that's the driving wheel, where the acceleration "happens" and it happens at the hub, where typically spokes fail. Front wheel spoke failures are much rarer, suggesting deceleration at the rim has very minor effects.
I suspect in a disc braked wheel deceleration at the hub will have the same effect as acceleration, this time both front and rear... actually more front than rear. So, it is not unreasonable to think that all else being equal, disc braked wheels' spokes are bound to last less and therefore the wheel needs some "overbuilding" as well as benefits from a non radial lacing pattern.