UKC

I have had my Mammut Genesis 8.5mm 50m half ropes for a long time now. In the past I have just bought another pair but Mammut no longer make them.

What have other MG8.5 devotees gone on to replace them with?

I'm in the exact same position as you.  I'm thinking Beal Opera Golden Dry 8.5mm, which have the benefit of being triple rated, however I want to go have a feel of them before committing as I have read they can be a bit stiff.  

It looks like Dicks and Banana Fingers stock them so when I next head into town I'll take a look.  

They have a much lower sheath percentage which will likely make them less hard wearing

I looked at those but am a bit reluctant to go for something heavier (ok only 3g/m) - feels like a step backwards. Plus thinner sheath

https://www.ukclimbing.com/gear/climbing/ropes/half_ropes_for_uk_trad-10960

I've used the genesis and the pheonix and the pheonix are also very hard wearing for an 8mm rope. They do tangle more than the genesis though IMO. The Mammut 8.0 Alpine Classic Rope is the new equivalent. 

Have you looked at the Edelweiss Oxygen II 8.2

Interesting suggestion thanks! 43g/m. UKC suggests it's mainly for ice and mountaineering but it might te a good option nevertheless

Had the Phoenix for ice climbing - fab for that but too stretchy for trad

Beal Cobra II

Thanks for the suggestion. Interesting UKC review of them 

https://www.ukclimbing.com/gear/climbing/ropes/half_ropes_for_uk_trad-10960

I used the pheonix for trad with no issues but I don't fall off much. If you compare with the genesis the dynamic and static elongation is comparable.

Not a devotee but I replaced mine (a long time ago) with Edelweiss Calanques which in turn were replaced with Beal Cobras. The Calanques were a lovely handling rope as are the Cobras which I've been super happy with.

At the current time I'd almost certainly replace them with another pair of the slightly newer Beal Cobra II.

Potentially in future (after seeing some more feedback) the Edelrid Starling Protect with enhanced cut resistance looks really compelling although I'm always slightly wary of buying the newest innovation that's not been tested extensively in the real world.

However, I've also got a pair of Twilights and two pairs of Mammut Serenity so I've utterly no need to consider things such as a marginal saving weight or wanting a triple rating.  Also, I tend to rate good handling, which is relatively easy to assess, over claims about long-term durability that are rather harder to substainiate.

I had the same dilemma just over a year ago. 
Loved my Ginesys so much and had put them trough 20+ m falls , jumaring , ice and mix , 100s of abs ( literally) and if money wasn’t an issue I’d go with them. At the end ended up getting Beal ice lines ... as figured 90% of the time would be long routes where you don’t really fall much . 
They look/ feel  a lot skinnier ( also a lot lighter) and since I’ve been really impressed. We did Marmolada south face , Piz badile NF , chima grande , some other stuff in the Dolomites as well as few days at Pembroke and the Wye . Once you get used to the way the look ( skinny) they are perfect. Now if I’m let’s say going Pembroke to try something that I know I’ll be taking falls for sure I’d tie myself to sth a bit more substantial but for 90% of my climbing the ice lines are brilliant. 
Another advantage is when packing for alpine routes because they are so skinny it actually takes a lot less space. 
That’s my 2 cents I guess .

I haven't used the Mammut Genesis for a fair few years now, but for a long time they were my benchmark as far as double ropes went.

Whilst I've used a variety of 8mm ropes over the years, including the Beal Ice Line and the Mammut Phoenix, I wouldn't recommend them if rock is your main focus. The decrease in diameter definitely has a knock-on effect to the durability, but most noticeable was the stretch, which is pretty substantial. This has (on more than one occasion) led to various people I know getting injured, as the falls they've taken have been significantly further than they'd expected. If rock isn't your focus, and winter is, or you just don't intend to fall, then it's still worth being aware of, but less of an issue.

In light of the above, I've tended to favour something in/around the 8.2 to 8.4mm mark in recent years, as that feels like you get the best of both worlds: it's a bit lighter than 8.5mm, and feels a bit stretchier, but not too stretchy. 

Ironically the various ropes I've been using have either been discontinued (DMM Migrant 8.2mm) or are really tricky to get hold of and/or really expensive when you do (Sterling Duetto 8.4mm).  We've got the Edelrid Starling Protect 8.2mm coming in to review soon and I'd be happy to keep you posted with any first impressions. 

Sorry I gave the wrong link for the review of the Beal Cobra IIs. Here is the correct one:

https://www.ukclimbing.com/gear/climbing/ropes/beal_cobra_ii_half_rope-1000...

Mark, Petar and Rob: thanks all for the comments and suggestions.

Rob: yes, would be great to hear impressions of the Edelrid Starling Protect 8.2 mm. It is the front runner for me - a bit thinner and lighter than the Mammut  Genesis. After all this time of hammering the Genesis it would be nice to have a step up. Rock is my exclusive focus with them and I do fall off and climb with people who do, so too much stretch is bad.

They should be here shortly, so feel free to either drop me a direct message, start a new thread, or accost me at the crag as/when they do. 

Their arrival is quite timely, as my Duettos really are on their last legs. They now bear a closer resemblance to a caterpillar than they do to a rope (so much fluff...),  but have survived five years of absolute battering, so deserve their time as a doormat.

Generally speaking, longevity is directly proportional to diameter, so as Rob said, skinny ropes on abrasive or edgy rock are not a good idea.

The other thing to consider is holding falls or abseiling on skinny ropes - things get a lot harder below 8.5mm unless you have specialist devices, gloves and/or weigh little.  I'd recommend trying before buying.

The rope stats show the beal ice lines stretch much more than the alpine dry (new pheonix rebranded) , whilst the alpine dry don't stretch much more than the genisis. However the beal cobra 2 stretch nearly as much as the ice lines and more than the mammut ropes

Ice lines static 11.5% dynamic 37%

MAMMUT - 8.0 ALPINE DRY 8.5. 30 ,

geneisis 7.3, 29,

beal cobra 2 11.5 35

It appears thickness of rope isn't the only factor here. I think you'll also find ropes with lower impact forces tend to stretch more and that can break the rule of thickness being the main factor here in some cases.

Anecdotally I didn't find pheonix stretched much more than genesis and I've owned both. But when i moved close to swanage I figured the sharp edges and the greater amount of cragging I was doing vs mountain routes with a walk in pushed me to go from 8.0 to 8.5 on my next upgrade. Mainly for confidence regarding sharp edges tbh but I figured they would tangle less and be a bit harder wearing too.

"Generally speaking, longevity is directly proportional to diameter, so as Rob said, skinny ropes on abrasive or edgy rock are not a good idea."

I don't think rope thickness is the only factor here, its the amount of sheath and the thickness of it ( as well as other things like treatments and weave) . For example very often tripple rated ropes have lower sheath percentages. It's obviously a grey area trying to say a tripple rated 8.5mm rope will wear faster / slower when used as a half rope than a workhorse 8 / 8.2 mm half rope with a higher sheath percentage as we don't have accurate data. But I know where I'd put my money (other factors being equal).

I fully agree with you about belay devices and if you climb a lot on rock with sharp edges it can be a consideration too regarding ideal half rope thickness.

Good point and borne our by my experience. I changed from Genesis to Phoenix and, other than feeling skinny and weighing less, noticed no discernible difference in how it performed in falls, certainly no stretchier. On the other hand, some of the thinner or triple-rated ropes I've used have felt really stretchy/bouncy.

Am I right in thinking that the diameter that a manufacturer quotes only has to be accurate to +/- 1 or 2 mm?

Yeah I've read something about that also, its 2mm isn't it?

I'm thinking of getting new ropes as my old ones are ... old.  My gripe is that the manufacturers' websites seem to contain very little information on which to base a comparison.  To take one example, Beal seem to have at least 3 categories of climbing rope - Active Line, Intensive Line and Mountain Line - and several different brands within each, not to mention different dry finishes and Unicore technology.  Is there anything to explain the difference between them? Not that I can see. The detail is there for each rope (in French) once you click on it, but there are dozens to look at.   If theyv've gone to the trouble to develop all these different ropes you'd think they would want to tell us about them.  Most of the other manufacturers' websites are no better.