Half / twin rope belaying devices and friction with < 8.0 mm diameter

One other point about the Alpine Up is that you belay like normal. You can give out slack on or two ropes, and take in slack on one or two ropes, with no interference from the braking mechanism. You don't need to hold it funny, angled, or defeat a mechanism to allow function. It's super smooth like any non-ABD belay device.

Martin Berlin wrote:

I got the ATC-Guide Alpine in the mean time and I am pretty pleased with the performance. I even found it to have significant friction on cords of 5 and 6 mm [which I would not rappel on, to be explicit here.]

I'm thinking about getting a second belay device. My climbing partners often use the reverso or ATC (Guide), which I am not too happy about. 

On top, I read above that @climber pat and @Jake Woo recommend the CT Alpine Up. I tried to find some reviews online, but there does not seem to be a lot of info on double rope belay in general or on specific devices. Are there more opinions here on this forum on the CT Alpine Up? 

Thx, everyone!

There have been several threads on the alpine up.  Here is one Alpine up.  I generally use mine for single ropes, 9mm and less.   I have used the alpine up with 8mm double/twin ropes often enough to know that it works well.  The issue many people have is that it has more friction when used in autoblock mode belaying from above than an ATC.  The Alpine Up is actually much more pleasant to use with smaller ropes such as the ones you want to use.  The Alpine Up certainly does not appeal to the microtraxion as a top belay device crowd.  

RGold is a big proponent of the alpine up and has some insightful comments. Some of which are in the thread above.   It appears most of his climbing is with double ropes.  One thing he preaches is that the alpine up is one of very few belay devices capable of handling a fall factor 2 fall where the leader falls before clipping any protection.  This scenario will cause almost all tube belay (ATC etcetera) devices to fail catastrophically.  RGold has experienced at least 2 fall factor 2 falls as a belayer which might be the record.

One big issue with the regular sized ATC with skinny ropes in autoblock mode is the strands can invert (top strand becoming the bottom strand) causing all friction to disappear.  The skinnier the rope the easier for this to happen.  This 'feature' is sometimes used deliberately to remove the device from the system while weighted, transferring the belay to something else.  Some ATC-like device, I forget which one, directions include a method of clipping the blocking carabiner in such a way as to prevent this inversion.

Good point about guide mode. I do not like the Alpine Up in guide mode as it's kind of faffy to set up and high friction. I usually have a GiGi with me that I use to belay from above. That being said, I love the Alpine Up lead belay function so much it's worth carrying a different device for guide mode. Or you can switch devices with your partner so you don't need an extra device.

I've been using the CT Alpine Up for many years with 8.5mm half ropes.  I've tried a slew of other gadgets and for me the Alpine Up is the best for half-rope technique.  I would have mentioned it but am not sure how it performs with much thinner ropes.

climber pat wrote:

There have been several threads on the alpine up.  Here is one Alpine up.  [...]

Thx. I read through the thread and also through this one: 

https://www.mountainproject.com/forum/topic/109687295/climbing-technologies-alpine-up-review

The only mentioning on something thin I found was from stolo, who claimed he tested assisted mode with 6 mm cord. He does not provide any background on how he conducted this test though. 

New article [german] from the German Alpine Club on the topic: 

https://www.alpenverein.de/artikel/risiko-tubes-und-duenne-seile_87e77817-03d2-48b0-b400-da8a048c01a8

Couple Take Aways: 

• DAV Safety suggests using special alpine tubes for smaller diameter ropes and half rope technique (like consensus in this thre
• They also recommend using belay gloves with thin ropes in case the rope slips more than 30 cm  through your hands. 
• In addition, they suggest to use twin rope technique for the first couple draws. If you don’t, falling fall factor > 1 into the belay station on a single thin rope would not be feasible to catch with many systems. Using twin technique obviously increases friction by factor 2.
• They also suggest checking your tube regularly, as falling on slack in guide mode may twist the tube and damage the rope (emphasis on the point, where the biner regularly is squeezed into the tube while abseiling).