Why are there 4 and 5 bolt cranksets?

[beyond rational]

Why do 4 bolt and 5 bolt cranksets exist? was the introduction of 4 bolt purely down to wieght?

[mat205125]

Weight was one of the major selling points that was published when they were introduced.

Shimano steering their monopoly machine in a new direction when the number of 5 bolt competitors got excessive could be a scinics opinion.

[BadgerBenji]

I have to agree with Matt.

There is an issue with larger chainrings, hence road has stayed at five. Even shimano's marketing powers cannot change the laws of physics.