So when I am aid climbing, I have this tendency to carry quickdraws... the other day I wondered why I do this? Why do my pieces need them? I don't think they do unless the route is zipping or zagging. So can anyone tell me why I shouldn't go "old school" and just carry single biners to clip into?

So my wife was leading the dihedral variation to the first chimney pitch on Half Dome, leaving single biners on the many fixed pins and stoppers. At the top of the dihedral you penji right into a flaring slot. So she makes the penji and is climbing up the slot when she realizes her rope drag is soo bad she cannot move. The rope snaked up through the pins and the penji point was the final straw, which she is level with at this point. To say she she was not a happy camper at this point might be understating it a bit let me tell you. As the crack was bigger than our largest piece she had to downclimb and reverse the penji have me lower her 30 feet to unclip some pins.

Moral of the story is always have some nylon (or 2 biners) on fixed gear, especially pins in a tight corner.

Don't forget about equalizing multiple pieces of less than bomber gear in order to get a good placement too. Always carry an assortment of different length draws and slings. Better yet, give up aid climbing and go ice climbing instead... aid is too much like vertical construction work...;-)

Single biners can come unclipped when loaded, or crossload and explode...hence the practice of two biners (look at old yosemite pictures)...hence quickdraws. Some cases it's fine...wires, cams with slings (as they move some)....on pins, it can be Muy Malo.

just my nickel. not worth much.

sweet, single biners it is then...

I've noticed several photos in the last few years where aid climbers are putting draws on every single piece. Certainly you need to have a few runners with you and be mindful of the run of the rope, but I just can't see why you'd want to carry the bulk of enough draws for an entire aid pitch. My vote is for double biners on most pieces.

I've never aided, so I may be asking a very stupid question here, but...

If you are going to bring and use two biners per piece, isn't that 9/10th of the weight and bulk of a quickdraw anyway, especially with the floss-like runners being used now?

I can see situations in which single biners are okay: if the route follows a straight line and also if the pro allows the biner itself to sit perpendicularly to the rock (this allows the rope to run smoothly without pinching it against the rock).

I think you see those double biner setups in the old pictures because the top biner is attached to a piton. If the eye of the piton is off to the side (like a knife blade, a lost arrow, or an angle in a vertical crack) then the two biners are necessary in order to change the angle of the lower biner to allow the rope to run smootly.

I say, single biners unless two are needed for the above reasons.