Derailleur Hanger replacement for GTS R5 road bike frame
My local bike shop and I'm sure most others have a large "deraileur hanger" wall chart from Wheels Manufacturing or other supplier. The 170 plus pictures are life sized. All that is required is a visual match. Wheels Manufacturing has a database on their website but doesn't list a GTS R5. I would either visit your local shop or contact Wheels Mfg.com customer service dept.