Right so i got to use one of these bad boys down the wall a few weeks ago, a friend had just bought one and he showed me how to use the thing before letting me rip belaying a couple of friends throughout the evening. I belayed them on my 9.8mm Mammut Tusk which to be honest, is probably more like 10mm now.

On first acquaintence i was suprised at how large the device was, from the photos and because it's designed for slimmer ropes i was under the impression that it would have been smaller than a grigri, it's more or less the same size, however it's a little heavier in terms of weight. Overall it feels well made and very solid.

On first using the device i've got to say i was amazed at how easy and fast it was to pay slack out and take it back in, and the device flawlessly locked up immediately in the event of loading.

Upon reflection i've got to say i really rate this device. In comparison to the grigri i think this device is also open to less miss-use, because of it's design it won't fail in the same ways that a grigri can through improper use. For example grigri's are known not to lock off if the device is gripped in such a way that the top of the unit is kept down when paying out slack on a thicker rope. With the use of the SUM there is no need to operate the lever at all (no matter what the recommended diameter of the rope) to pay out slack only to lower. Even with the method that is suggested for paying out slack, it would be extremely difficult for you to keep the device in the same position paying out when it is loaded. This is because the device positions itself in such a way when paying out that it twists and tilts upwards when loaded thus jerking upwards and throwing your hand off. You'll have to see this to understand it fully but you'd have to be super stong to keep it down! Additionally your hand is also right next to the rope and it can be brought down to hold it in a fraction of a second. This immediately erradicates this risk from the equation.

The only issue that i have found that could result in the failure (other than grabbing the release handle!) of the device is if the belay carabiener is facing the wrong way round and the unit migrates round the crab. This could potenitally result in the handle catching underneath the device. This is issue is identified within the device documentation (which should always be read!) and should not be a problem if the device is used as recommended by Faders and the appropriate carabiener is used and is situated the right way round (i.e narrow end on your belay loop and wide end on the device). The use of a belay crab such as DMM's belay master would almost guarantee that this doesn't happen.

Like with all things however there are always gripes and cons. The differences i experienced were that unlike the grigri you cannot make small adjustments by using the feed method that is typical with the grigri, however with the SUM the method of paying out and taking in it was just as quick. Just something you'd have to get used to!

The other notable difference i found was with releasing the device once it had been loaded. This wasn't as simple as the grigri where you push down on the lever and it releases immediately. The device works similarly by also requiring you to push down on the lever but it's slightly more difficult to release, especially if the climber is heavier than the belayer (as my gf found!) This however was easily ironed out by walking a step forward to create slack before feeding more out.

Lowering also appeared to be more difficult with the SUM than with the grigri but personally i didn't find this to be of any significant issue. I was able to lower continuously, at a good steady pace, with no trouble via the method of pressing down on the lever with my thumb. My gf however again found this more difficult due to the weight difference and found it required a lot of force to press down on the lever to lower me.

Overall i was extremely impressed with the way the device worked and handled. If you're using ropes less than 10mm, which probably most of us are, then i think this is the Daddy! It feels so much safer and more secure when belaying skinny cords than with a grigri and lets face it, it's purposefully designed for it unlike a grigri which you see a lot of people using with skinny cords! In 12 months time i'm sure we'll be seeing this device on every sport climbers rack.

Some more reviews for you if you can stomach more reading. The bluedome.co.uk one is probably the most comprehensive.

http://www.faders.es/imgs/faders/Sum_EN.pdf

http://www.bluedome.co.uk/trailwalk/trailwalk3.cfm?review=554&mascat=13&subcat=32

http://www.rockandice.com/gear/145%20Field%20Tested.pdf

http://gravsports.blogspot.com/2006/04/faders-sum-review.html

http://www.rockclimbing.com/gear/product.php?p=3663

http://www.planetfear.com/review_detail.asp?r_id=747


Since writing this (which was initially a review sent in an email for some friends) i've used the device as my primary means of belaying and it has seen a lot of use including a recent 9 day trip to Ceuse, France. I used the device on a number of different ropes including a 9.2 revelation, a 9.4 stinger and a 9.8mm tusk and i was absolutely amazed with the ease and feeling of safety of the device. Paying out slack was fast and re-adjusting also quick and a large number of big falls were taken with no issues at all. What is also interesting to add is that a number of my climbing partners were also aquainted with the device during the trip and they were all extremely impressed with it's use and in all much prefferred it to using a grigri.

I've got one. Used it at the Red for a 4 days of climbing in May 2006. It works very smoothly--I think a safe brake hand position is a bit easier with this than the grigri.

The only 'gotcha' I found is that when held at a certain angle it won't feed rope, no matter what! But simply pushing the entire device down a bit allows you to feed slack as smoothly as with any device out there, including non-autolockers.

We used it with my Beall FLyer 10.1 and also a PMI 10.2. Both ropes fed smoothly through the Sum, and lowering was a bit more controllable on my Beall than with the grigri--that rope seems to fly through the grigri for some reason. I'm much more confident using this device with thin ropes.

If you've got a grigri there's no reason to get one. But if you're looking for a good device for skinny ropes, I'd get this over the grigri.

The weight of the Sum is 260 grams. A Grigri is 225 grams.

It's one month since I use it and I'm really confident with it. It works really well. I have had some falls since then and it has always braked really firmly.
I read, and it can also be felt, that its braking is dynamic meanwhile the Grigri is static, so I feel secure when I use it not only in sportive climbing but also on classic routes. In this kind of routes, friends, cams and rest of anchors suffer in falls with high shock loads, and there is where the dynamism of the Sum makes climbing safer.
Moreover, with the Sum I use my new thin ropes without problems, which I couldn't do before.
In my opinion the best belay descender ever.

Hi golleagues! I bought the Sum two weeks ago and it works perfectly!! Very solid catching in falls... and easy to feed the rope.
As it has a very much dynamic braking (I already felt it, but its specs are really amazing) I use it for both sportive and classic climbing, and feel a lot more comfortable if using friends or cams.
I really recomend it to you. My best investment in a while.

I got to test one of these and was not at all impressed. It's a heavy device, possibly even heavier than a gri gri. Loading the rope is difficult, you really have to stuff it in there, and using with a 10mm or bigger rope is just not practical, these thicker ropes take some real effort to feed. All in all, it doesn't bring anything to the table that the gri gri doesn't already handle better.