What's the skinniest diameter half rope for rock?

Looking to buy a set of halves for rock and wondering what the consensus on how skinny you can safely go. I would ideally like to go as thin as possible while still being able to simul-rap. The thinest I have ever simul-rapped on is 9.4 so I am very curious as to how low you can go.

What about using this 7.8 such as this for rock?
sterlingrope.com/product/15…

I've got a set of 7.9's. Only a couple of months old, used twice and they work great. I just cant get the image of those skinny little things cutting over a sharp edge out of my head. Even though they work great I'll sell them to you for a great deal.

If you're gonna simul rap you would definitely want to add some friction, ive clipped a carabiner to my leg loop, then one to my belay device and zig/zagged the rope down and back up. Works great.

When you see it in person, 7.9 is pretty F-ing small.

I have one of those Fusion Photons. It's surprised me, but the 8.4 (Fusion Duetto?) feels a lot more beefy in the store for peace of mind. I've seen reports of the 7.8's put through their paces in the Alaska Range on some long, big routes, coming out looking good for what that's worth.

I have the duettos 8.4s...they are great. Found on sale for like 99$ a rope last winter.

I have used my 60m 7.8 monster twin/doubles on more than 5000' of rock climbing with rappels. I have rappeled on a single 7.8 monster before we had fixed, but definitely use two carabiners and gloves. I even took a lead fall this last weekend on them. They are holding up well. Minor sheath wear and still maintain good handling. My only dislike is that they tangle easily, but this should be expected with ropes that small.

Keep in mind that the thinner you go the more likely they are to get stuck/hung up. Seems like every time I climb on sub 8mm twins I end up dealing with major headaches.

Great input! Thanks MP.

The Metolius 7.8 are the thinnest half rope I have seen.
I think they are made out of unicorn hair to beable to take 6 falls as a half rope...

metoliusclimbing.com/monste…

It definitely helps to have good rope management with the 7.8 monster. We mostly run them as twins, then stack them together (one pile or lap coil) when at the belay on multi. It is true that they can get hung up easily, especially in windy places. Although they can be blown around with wind, we have used them at Red Rocks on many climbs with no incidents (partially luck). The nice thing about long multi's is you can butterfly coil them together and carry as one rope backpack at the same weight as a single 10mm rope. The only downside to coiling together is it takes a little bit longer to flake out for the first pitch. Even though the diameter is only slightly larger than cordalette, friction hitches still work well, even the klemheist on a single strand.

Ben B. wrote:I don't understand all this discussion about rapping on twins... it's not that hard. I've got a set of 7.7 Ice Floss that I've rapped on with a Reverso... no extra biner, no gloves. It's just not that bad. I've also rapped on 6mm accessory cord, same device.. I don't recall using an extra biner, but I was definitely wearing gloves.. maybe it helped? Test it out at the crag before you take it into the alpine, if you're concerned about it.. but this isn't new ground- people have been climbing and rapping on very skinny ropes for a long time.