A 27.5” rear wheel isn’t really about better cornering. Although it technically does corner better that is not the reason DH racers use them. They can corner just fine on a 29” rear. And having a tighter turning bike is the least of their concerns on today’s tracks.
The 27.5” rear wheel gives the riders more room to move around. They can get lower on steep plunges without running out of space. They can more importantly run their seats lower without having the rear tire hit/buzz the seat. At the very least they get a bigger range on where they can run their seat height.
At a certain height (say 6’1” +) then this is no longer a concern as the frame is larger and there is simply more room for bike to compress.
Nov. 17, 2020, 7:25 p.m. - Mike Wallace
A 27.5” rear wheel isn’t really about better cornering. Although it technically does corner better that is not the reason DH racers use them. They can corner just fine on a 29” rear. And having a tighter turning bike is the least of their concerns on today’s tracks. The 27.5” rear wheel gives the riders more room to move around. They can get lower on steep plunges without running out of space. They can more importantly run their seats lower without having the rear tire hit/buzz the seat. At the very least they get a bigger range on where they can run their seat height. At a certain height (say 6’1” +) then this is no longer a concern as the frame is larger and there is simply more room for bike to compress.