The new 105 is very nice. I had it on my 2010 Tricross Comp and it was as nice as Ultegra or Dura Ace. I have all 3 so I know what I'm talking about.
I had Rival on another bike and it was ok. I didn't like it as much as 105. It felt kinda clunky to me. 105 was very, very smooth. Maybe if you're talking racing there will be a difference to discuss that makes Rival better, but for someone like me that doesn't race anymore and rides paved and dirt roads, 105 was great.
I like the term brifter also.
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Demented internet tail wagging imbicile.