Mammut Pheonix 8.0

I’m looking at getting some half ropes for parties of three on easy multipitch. I was looking at the the mammut infinity 8.0. Would this me too skinny? I know that the genesis 8.5 seems to be the preferred rope for this, but seems like the 8.0 would be close as well. Thanks in advance for any input.

Mammut Infinity is their 9.5mm rope. Assuming you're talking about the Mammut Phoenix (their 8.0mm rope), yes, that's fine for use as a half rope. But you shouldn't take my word for it--look for a UIAA half rope certification.

Here's a picture of the certification on a Mammut Phoenix rope (from the Mammut website):

It's a bit hard to see, but there is in fact a half rope rating on there.

That said, there are real tradeoffs here if you choose the thinner rope. The thinner rope is less durable. The thinner ropes also seem to tangle more, so I wouldn't automatically assume that thinner ropes will save you time. Given you're using it for easy multipitch, I'd go for the slightly thicker Mammut Genesis. There are reasons this is a popular half rope.

Second the recommendation for Mammut Genesis.  These replaced a set of Sterling 7.9mm's that I found too thin for free hanging rappels.  As noted above, also find the 8.5mm diameter is less prone to tangling.

One more vote for the Genesis.  I had a set of them that lasted for years and can't say enough about their durability.  I have the 8.0 Phoenix now and like them as well, they would be fine for what you're doing.  If you're using them for a party of three however, you might as well get the Genesis.  The weight savings on the Phoenix isn't that significant (6 oz. for a 60M) for a party of three on easy routes (unless these routes have really long approaches or descents) - since two people each take a rope and the third takes the rack. 

Not mammut ropes, but I've been using Beal Ice Line Unicore 8.1mm at 39 g/m for several years. They replaced some heavier 9.0s. I've been happy with them - I use them for multipitch rock climbs with my family (and ice with other partners) and feel very comfortable. I was hesitant to go with the super skinny ice specific 7.9 option, and would probably get the same ones again were I to rebuy today. Double ropes get heavy and I have been happier on these then when using my partner's triple-rated, somewhat thicker setup as doubles.

I have had no issues with tangling, although, FWIW, my partners's heavier Beals tangle like crazy. The hand/weave/stiffness of ropes may have more influence on tangling than the thickness. 

I think it's about your comfort level and what you value (weight vs. greater sense of security and durability) 

another happy genesis owner here. they are burly and don't tangle very badly, even compared to a very supple 9.2mm "sending rope" that I bought (misguidedly haha). you will not have to worry as much about abrasion, sharp edges and stuff like that with these ropes which is always on my mind when working with really thin stuff. have climbed on what I think are some petzl like 7.5mm half ropes and those things just felt to dainty to be dragging across granite all the time - stuff like that is IMO more suited to winter / ice / alpine climbing where it is mostly in contact with snow and not rock. not at all necessary for easy / low angle rock routes - which often can involve more traversing and wandering routes meaning more opportunities for your rope to have to run around features which means abrasion.

Thanks for the advice. And yes I did mean the Phoenix 8.0

When I went down this path last year, I opted for the 8.5mm Mammut Genesis half ropes. Everybody here said they were truly work horses and lasted a long time. I don't have a ton of climbs on them, but I have nothing bad to say about the ropes.

I've been using the Pheonix for a few years now. Especially love it when the rap calls for 2 ropes. I've taken a couple whippers on them and at first, it made me really nervous climbing on them but got over it. They do make a few of my partners nervous due to thinness (durability) especially on sharp rock but that's why you have two ropes! (I know, yer gonna die). After 2 years, I had to replace one of the ropes as there was a spot that looked a little suspect. 

Belaying on them makes me a little apprehensive but I make sure to use the mega jul with them.

Thanks for the info from everybody.
Just to focus in a little; I’d like to focus specifically on using the half ropes for parties of three and bringing the seconds up on individual lines. And doing so on easy multipitch. Some things that come to my mind are:
1. Is 8.0 enough of a safety margin for a second?
2. Is 8.0 more tangley(spelling) than 8.5?
3. Is rappelling on 8.0 too tricky?
4. Any other things I’m not considering?

I’ve basically decided that I’d like to get some half ropes and am just trying to decide between 8.0 and 8.5. Thanks again for all the help.

Depends on how soon you want to replace them

I've been using the Phoenix to climb as a group of 3 in the PNW and Bugaboos for the past couple of years. I really like them. They are quite durable if one is mindful about rough rock and sharp edges. I'd recommend getting the 8.5 doubles if you're even the tiniest bit squeamish about following on a 8.0 or you want your ropes to last a bit longer.

Some things that come to my mind are:
1. Is 8.0 enough of a safety margin for a second?
2. Is 8.0 more tangley(spelling) than 8.5?
3. Is rappelling on 8.0 too tricky?
4. Any other things I’m not considering? 

My experience:
1. Yes, ok as long as no sharp edges are involved; that being said 8mm looks rather thin when you're looking up at a hard move.  
2. Most definitely YES
3. What's too tricky?  If you use a good, "grippy" descender with "teeth" and aren't rapping 100 ft in free space probably OK.  (One "trick" to increase friction is to use two identical locking biners with your device.) Novices on vertical-to-overhanging raps??? I'd worry a bit.
4. STRETCH - if "second A" is 15 ft above "second B" and falls, will the stretch allow A to hit B and knock 'em off?
   

Fat-lover here. My last half ropes  were Edelrid Swifts (8.9mm), purchased 4 years ago and just retired.  Sad to see they do not seem available at a reasonable price. Moving to Mammut Genesis.

Got caught in the rain on some half ropes that were sub-8.0 mm a couple years back.  Talk about s...t...r...e...t...c....h on the 9 adventure raps to the ground.  All anecdotal, I know.

Julia Lee wrote: I've been using the Pheonix for a few years now. Especially love it when the rap calls for 2 ropes. I've taken a couple whippers on them and at first, it made me really nervous climbing on them but got over it. They do make a few of my partners nervous due to thinness (durability) especially on sharp rock but that's why you have two ropes! (I know, yer gonna die). After 2 years, I had to replace one of the ropes as there was a spot that looked a little suspect.

Belaying on them makes me a little apprehensive but I make sure to use the mega jul with them.

I use the phoenix as well and have used a mega jul. Have you taken any overhanging falls with the mega jul? I found that with the edelrid strike biner it offered VERY little braking force, actually my partners hand got sucked right into the belay device. It was less assist than an ATC on the high friction teeth.

I use a regular tube device with two biners through the rope and belay loop now instead, it still feeds well and provides a great amount of power braking. Have caught some longer falls with both 7.5 and 8mm mammut ropes and been happy.

Also another phoenix user, bring it as a tag line or for parties of 3. Has seen a lot of abrasion on slab routes and sheath holds up great, more durable than some 9mm ropes I've used.