Cranksets with asymetrical bolt patterns

[avanti]

All my chainrings to date have had symmetrical chain ring bolt patterns which allowed me to use chainrings from various sources. I note that some of the newer crank sets use asymmetrical bolt patterns which I suspect will reduce my choices for chain rings.
Is there a reason for asymmetrical bolt patterns or is this a sales gimmick?

 

[JackRabbitSlims]

regarding shimano's 4 bolt asymmetric bolt pattern
this allows the use of compact or standard gearing on the same crank arms

the X shaped bolt pattern removes the 5th arm which used to lie in the area with the least amount of torque being applied to the chain rings (according to shimano)
the orientation of the remaining four spider arms puts them in line with the area of the chainring requiring the most reinforcement resulting in the same power transfer & a lighter set of cranks

 

[Bustedknuckle]

All my chainrings to date have had symmetrical chain ring bolt patterns which allowed me to use chainrings from various sources. I note that some of the newer crank sets use asymmetrical bolt patterns which I suspect will reduce my choices for chain rings.
Is there a reason for asymmetrical bolt patterns or is this a sales gimmick?

Most, like shimano and Campagnolo do 2 things. Allow them to make one crank and then any chainring combo, including compact, on one crank...53/39, 52/36, 50/34..etc, one crank...and means ya gotta buy their chainrings..

 

[King Boonen]

This happens in MTB too and I've noticed that very quickly aftermarket chainrings have been appearing on the market in the correct bolt pattern. I doubt they can patent it so it's very little work for a company to alter a design to suit.


On the road I'm not sure as I just buy Shimano...

 

[42x16ss]

All my chainrings to date have had symmetrical chain ring bolt patterns which allowed me to use chainrings from various sources. I note that some of the newer crank sets use asymmetrical bolt patterns which I suspect will reduce my choices for chain rings.
Is there a reason for asymmetrical bolt patterns or is this a sales gimmick?

Most, like shimano and Campagnolo do 2 things. Allow them to make one crank and then any chainring combo, including compact, on one crank...53/39, 52/36, 50/34..etc, one crank...and means ya gotta buy their chainrings..

There's always a trade off

At least the new 4 bolt stuff from Campy and Shimano is pretty good