You appeared to have angled the rear ( wing mounted ) landing gear backward, to change the angle of attack.

The problem with this is you are effectively changing the point where the plane rotates with respect to the C.G. as the nose tries to come up.

This is like putting a big weight on the nose just before takeoff, but removing it once in flight.

So it is not a good idea.

It is better to either shorten or bend the wires themselves a bit.

Typically we use a "V" bend to shorten piano wires when used in linkages, etc.

You may be able to do the same to the rear landing gear wire.

I'd use a wire bending tool to get this right and matched on both landing gear wires.

At worst you can go to a LHS and grab similiar piano wire and bend a new set of rear landing gear.