If buying new ?, why would you buy 10 when 11 has been the standard and is a much refined group. The front derailer was redesigned for the 105 5800 series, was a HUGE improvement and we are now up to the 7000 series. It's a really great group at a great price for performance. Only and BIG question is if you are using vintage wheels, will they accept an 11 spd. cassette ?