Above the bells

The chamber at the top of the tower held the bell mechanism. Sunlight entered through four open arches, making the iron wheel and oak frame easy to see. Two beams crossed the chamber at shoulder height, forcing me to stoop beneath them. The wheel occupied the centre, leaving only a hand's width between its rim and the stone wall. A coil of new rope hung neatly from a hook.

From the passage, select two words or phrases that suggest it is difficult to move around the chamber.