Speed is not my friend.
If a group wants to ride faster than 20+mph and frowns upon us old guys sucking wheels, then I cork out - if on a double geared for mountains/long steep hills. One has to pick his horses for the courses.

Downhill speeds faster than about 30mph have me considering brakes, not another cog.

But, to each his own. We all get our kicks a bit differently.

SethAZ - I've only been 50+mph a couple of times - and only when riding my tandem - as a single. Never on a 1/2 bike.