How quickly do you want to get to the top? It's beatable on pretty much anything you're likely to be running and gear choice is a personal thing. On the day, I did it geared (39x16/17/19) and was 'comfortable'. On the Norths Death TT I did it fixed on 50x16 and was definitely not comfortable. Still got there.
(and not slowly either, the latter was a flying start so not directly comparable but still would have placed well acceptably in the climb proper)
How quickly do you want to get to the top? It's beatable on pretty much anything you're likely to be running and gear choice is a personal thing. On the day, I did it geared (39x16/17/19) and was 'comfortable'. On the Norths Death TT I did it fixed on 50x16 and was definitely not comfortable. Still got there.
(and not slowly either, the latter was a flying start so not directly comparable but still would have placed
wellacceptably in the climb proper)