I prefer mostly 13cms, one stubby (10cm) for thin ice and one 22cm for anchors/V-threads.

Like Dan said, the strength is in the teeth, not the tube but that is assuming solid, well-bonded ice which you obviously aren't going to find all the time.

For those who quote Will Gadd, don't forget to quote this as well:

Dig hard to get to good ice for screws.

Sure the 13cm screw has the same thread length as the 16cm, 19cm or even the 22cm, but I don't have an adze on either pair of my ice tools & find a little more comfort with longer screws that can dig deeper into more solid ice. Then again what do I know about ice climbing, ya'all crazy.

Before I knew better, I bought a ton of the longest Grivel 360s, couple of the medium size.

Great screws - my favorite that I've used. Small hanger to fit in tight spots, spin in like a demon. Racking is okay once you get your system down.

I've since added 4 of their shortest screw (12cm). Those, plus the couple 16cm, and a couple long dogs do the trick.

Good comments! Thanks for the video Dan. I agree if you have great ice then 13 cms should be good.

Wally

what I carry is a BD express screws I like using same brand screws and not mixing brands, things rack better.

1 10cm -Save for that one thin deperate area
4 13 cm- primary lead screws
4 16 CM-Primary lead screws
2 19 CM -useally I save these for the anchors.
1 22cm -Useally I use for V threads.

If a 13 or a 16 hits rotten ice either move on or grab a longer screw. I hate placing big screws on lead but sometimes you have to.

I use bd express as well, never had an issue. I've got a decent selection of sizes but most in the bag are 13s, a few 10s, a couple of 17s (old school) and a couple of 19s. One 22 for v-threads. Generally, if the ice is fat my strategy is longer at the bottom with screamers and shorter at the top with draws etc. Of course this is variable given the conditions, but that is my normal approach. I use the screamers low due to potentially higher fall forces than high on the pitch.