Anybody else suspect that the oscillations induced on the rear derailleur from the use of oval chainrings might be making the mech wear out much faster, especially those with a 'clutch'? Approximately 4000 extra cycles of movement per hour, is got to be having an impact over many hours of use. I had a SRAM Red road rear mech literally fall apart whilst I was riding, after using it with oval rings for a few years - probably only a few hundred hours riding time. Can't say this was definitely the cause, but it does appear quite likely. Perhaps this is why the big companies don't produce their own oval rings?

An intriguing possibility. Any tension from the front ring is on the "return" part of the system so would cause minor changes in tension on the jockey arm spring. Not used one on road or with SRAM mechs.

My rear mech (XT shadow so with clutch) lasted about 10,000km with about half that time on AB oval chainring. It was actually the clutch mechanism that broke first there was very little laxity in the derailleur mount or parallelogram mechanism.

A long term oval ring user with many thousands of miles on them on both road and mountain bikes, can't say I've noticed any increase in wear. There is a tiny amount of movement in the rear mech when you pedal but less than you get riding over a bumpy surface, even with a clutch mech. Even riding on the road produces more movement.

There are the same amount of teeth in contact at all times so any movement will probably be down to manufacture than design, in theory there should be no rear mech movement at all. You can run an oval ring on a singlespeed with no issues.

I run an oval on the singlespeed. There is a slight variation in chain tension as the cranks rotate, enough that I have to set the tension in the worst spot, tightest position. I use Absolute Black rings.

In theory there should be no tension changes with a elliptical ring? But the ring isn't a perfect ellipse as it's optimised for power/traction so is a funny shape.

Dude. Stop overthinking and take off the tinfoil hat.

FYI, SRAM do make their own oval rings.

Shimano don't make their own oval rings as the minute they did everyone would call it the return of Biopace and all of the senior management would have to commit harakiri again.

I've had Sram stuff fall to bits in a matter of a few miles with perfectly round rings. To be honest the tiny waver from an oval isn't going to compete with my terrible line choice clattering down a rocky descent.

Whitestone - it is worthwhile servicing the clutch mechanism in shadow mech's, It has definitely saved me two XTR's and one XT mech's. Sewing machine oil and not much of it is your friend, it's slightly fiddly until you understand how it works. Obviously I don't know the circumstances of your mech failure, but worthwhile pointing out to folk.