Narrow bars and leverage

I think needing to pull on the bars is down to fixed gearing being higher than you would normally choose for a climb. Or if you're accelerating. Once in the groove it's definitely about sitting down and keeping a rhythm, especially riding geared.

this is it. i'm aware its better to be in the saddle for maximum efficiency but when ascending i generally find that the extra power from torquing the bike side to side with my arms is needed to actually keep on going as i push a reasonably big gear(85 GI). the fact that it's a lo-pro, with bullhorns, probably doesn't help either.

that's the joy of fixed gear though, unless you have a wonderful cadence range, your gearing wont suit everything.