Buckling and Deflection Analysis on ANSYS

I performed an analysis on a bike frame using ANSYS Workbench 13 and I got the following results (I was trying to calculate deflection/deformation)

- Set a mass of 80 kg on the bike and calculated the deflection which ANSYS (Static structural) provided as: 4mm

- Tried to validate using Castigliano's theorem which was: 6mm

*SO far this seems about right.

Then I went on to Perform a buckling analysis on ANSYS and it gave me a load multiplier of 1.99 which is roughly 159kg.

- I set the mass to 159kg on ANSYS (Linear Buckling) and it gave me a deflection of: 1.1mm

- Validated using hand calculations and it gave me a value of 1.5mm.

* Again this also seems right seeing as the answers converge.

Now the problem is that how do I get a lower deflection with a higher mass?