How can one pass a write concern to #delete_many ?

In the 1.8 series of the driver, one could set an explicit write concern when deleting many documents:

col.remove({:_id => { '$in' => ids}}, :w => 1)

In the process of upgrading to the new driver, I've converted the query to:

col.find({:_id => { '$in' => pids}}).delete_many

but this is not 100% equivalent since I haven't set the write concern.

Since #delete_many does not take any arguments, how can I explicitly set the write concern?