Floating or not floating disks

[stpauls]

Sherco ST 125 2014.

The front disc is floating.  However, the rear disk is fixed.  Anyone know why this is so?

[zippy]

Front disc is lighter than water

Rear disc is not..............

 

  I shall go now................................................

[zippy]

My GasGas has a fixed front and rear disc.

I think the floating front disc allows for the caliper pistons to move better at the disc and give better braking and feedback.

My theory is:

fixed disc does not move so if there is something amiss with the pistons they will push on one side of the disc before the other.  Then you must wait for the pistons on the other side to move towards the disc to engage.

but with a floating disc the disc will move with the first pistons and "meet" the other set of pistons resulting in positive engagement sooner.

I may not know anything or this may be correct, I am not sure.  but I do notice a difference between my fixed disc GasGas and the floating disc Sherco I had prior.  it's not a huge difference, but I do notice it.

[tony27]

I wonder if it's something to do with front is easier to hit on things & by floating is less likely to bend?

[faussy]

The need for floating discs is so that the outer rotor can expand due to heat without warping. On most bikes the front brakes get a lot hotter than the rear meaning there isnt a great need for a floating rear disc. This is how it is on most road bikes, i imagine its the same reason for trials. The rear disc is also smaller so probably less likely to warp as well