Bowden extruder - pneufit adapter backlash / oozing reduction ring

In my Printrbot jr. Bowden setup (http://www.thingiverse.com/thing:90335) I used pneufit adapters to connect the PFTE cable. However, I noticed that especially during higher extrusion speeds, the pneufit adapters extend (see pictures). Increasing the effective cable length a few mm's, which causes backlash / oozing.

This ring pre-tensions the pneufit adapter reducing the extrusion backlash / oozing effects.