You guys are all just blowing smoke. There is no direct comparison to Sora and Tiagra.... rx-100 was 8 speed(there may have been some non sti 7 speed too) and a contemporary of rsx 7 and and 105 8 speed. rsx 7 speed was bottom end. rx-100 was the next level up and was nothing but 105 with a clear coat finish rather than the paint on the 105. Many preferrd the looks of the rx-100 to the 105. RSX was later upgraded to 8 speed before the introduction or sora, and at that level it was nothing but rebadged 105 8 speed.