Hello ive seen on some bikes recently and chad reeds these auxilary tanks for the fork and lines? What advantages do they hold and wat disadvantages?

Got pics?

The purpose of "sub tanks" in general is to increase the volume of captive air in the fork.  This was originally done most often with the single chamber KYB forks such as the YZ426 had so that the oil level in the fork could be raised high enough to prevent excessive foaming without the fork becoming harsh deep in the stroke as a result of too little air volume in the fork.  Other little sophistications to the scheme were added later, such as one-way metering valves to add an element of adjustability to their behavior, etc.

Other than the complexity of the setup, one disadvantage is that the tanks have to be dismounted and drained back to the fork periodically, as oil tends to migrate into them.

Twin chamber forks don't usually need the tanks as much, so you don't see them used as often any more,  but they still show up now and again.  Exactly why Reed's team deployed them is something I can't say for sure.

Dasquriel, on 13 April 2012 - 01:01 PM, said:

Is this recently or in years past? The tank was useful on older fork technology but not anymore.