Ignoring the effect on steering for a minute. Will a shorter stem change the way a rider's position when jumping and landing?
I assume it must or downhill bikes wouldn't have DM stems. At that level a rider is surely counter-steering rather than moving bars?
How much stem length difference are we talking about?
DH bikes have direct mount stems because dual crown forks make that (superior) attachment method possible.
Yeah dh stems are normally no shorter than normal stems, they just stop the bars spinning in a crash so you snap the brake levers more easily
The answer the question then yes. A shorter stem will move weight back. And for jumps less weight behind the front axle is a good thing.
Jump bikes and BMX tend to have short stubby stems.
You're looking at it the wrong way round. Short stems are needed to quicken up the steering made slower by slack head angles which are needed to make the bikes stable at high speeds on rough ground and complimented by the longer toptubes* which also add stability by increasing wheelbase as well.
*enduro bikes Vs DH bikes, enduro tends to be long reach short stack, DH tends to be shorter reach and higher stack.
In terms of jumping, technique and shock tunes will make way more of an impact than stem length.
Jump bikes have short stems because they like nimble handling (because a jump bike and a street/skatepark bike are basically the same thing) and it makes them stronger.
The question was if a shorter stem will change a riders position. It also stated "Ignoring the effect on steering for a minute"
So the answer is yes, it moves it back.
A shorter stem will move weight back.
