Decreasing Friction with a GG3 HUB Setup (updated 02/16/23)
This is the third in a "holy trinity" of GG mods I've done over the years on a GG. To recap - there are two main ways a GG can be used for LRS: hanging and backwards (known as "inverted" by many) and the HUB (held upside-down and backwards). The inverted method, if paired with the right rope, is great for upside down falls and steep terrain with no objective hazards and it doesn’t require any modification for using it this way. However it needs falls with a significant “jerk” to overcome the GG spring tension in order to lock-up. This can lead to not locking up when high-clipping and sagging on the rope. In contrast, the HUB method is good for high-clips and having the security of being being able to hang on a piece and lock-up at any point in time; ease of lock-up results in shorter falls; and for climbs with objective hazards and low angle slabs, FOR ME, the HUB method is preferable. The downside of the HUB method is it won't hold an upside down fall so a backup is mandatory (which it should be with any device and method). To achieve this functionality requires significant modification fo the GG which is a significant drawback for most climbers. The three mods are: 1) drilling a small hole in cover so that it can be held upright with a cord; 2) disabling the spring so that it will lock-up immediately in the event of a fall or a high-clip (if a GG+ is used this is unnecessary because of the dual spring mode - however it will never be as safe and and lock as easy as a GG3 with the disabled spring); and finally, 3) the mod described in this article will be modifying the rope guide tab on the cam arm to decrease friction in the feed.
This last mod has the least affect of the three mods but if wanting to get the last once of performance out of the GG with the HUB setup, then it is worth considering. It should only be done after the first two mods and using with the rope and setup that you’ll use. It may be that it is unnecessary or undesirable…read on.
Before describing the mod and how to do it, I'd like to take a bit of a detour and talk about rope feed and friction in general. While ease of rope feed is usually thought of as one of the most sought after characteristics of a lead rope solo device, it needs to be understood in context. The device with the least amount of friction is NOT NECESSARILY the best LRS device. That is because feed and backfeed are in an inverse relationship with each other: the easier a device feeds, the more likely back-feed will be an issue. As with many things ultimately it will depend upon an individuals preferences given their setup and types of routes they climb.
A device like the Revo is generally considered the device with the least resistance and best feed. However that also means that it will be the first device (everything else being equal) to back-feed during a lead. Other factors that will affect back-feed is the angle of the rock face and if the rope drags across it; the size and type of rope being used; the length of the pitch, how many pieces of gear the rope travels through before getting to the LRS device. A lower angle climb with many objects or a horizontally wandering route will take weight off the live end of the rope and reduce the amount of back-feed. Finally the size/weight of the cache loop acting as a counterbalance will affect the degree of back-feed. So pursuing the best feeding LRS device needs to be done in relation to all these other factors.
The Silent Partner and Revo both have excellent feed (Revo more so than the SP because of the clove hitch used in the SP). Both are essentially giant pulleys that the rope travels around and the wheel/pulley is free to rotate. The GG’s rope path on the other hand, goes around a non-rotating cam and then changes direction where it exits the device. The friction comes from the the non-rotating nature of the cam and the change of direction/bend in the rope when it exits the device. Any time the rope makes an “S” bend, depending upon the diameter of the bends, it can significantly increase friction. See the first photo above that illustrates this.
So, if you look at a stock GG3 HUB rope path, it is easy to see how the cam rope tab causes this “S” bend. Depending upon the size and stiffness of the rope this may or may not cause more friction than is desired. If it’s not prohibitive, then this last mod maybe moot. If there is significant friction when climbing and pulling slack, then it may be worth considering this third mod.
However, as shown in the photo to the right, in a weird fall, it could get caught behind the cam arm. While I’m personally reticent to use it for LRSing, it didn’t stop Keita Kurakami who used a similarly modified GG+ with an 8.1 mm rope when he rope soloed the Nose! (https://www.facebook.com/keita.kurakami/posts/pfbid02sUykWXzczJF3bJrUx3jKRGUY1sEQ8ApCHkciN7DDYNFiN83QH5mt4tuqDeZhKRqWl) http://www.alpinist.com/doc/web18f/newswire-kurakami-herson-free-the-nose?fbclid=IwAR13Alcfn2izJ6aMrhAKJ3Oy-jVQVc__rPXu9eamcJTZ4UMpmXn5oacN-08.
I’m sure the feed with the small diameter rope was slick as owl shit, but I’d be nervous regarding the possibility of it getting caught behind the cam arm and getting sliced. In his defense, he did take 50+ falls in practice and training for the Nose and on the climb itself took 10 falls on the Changing Corners and the Great roof. Also, in light of the discussion above, it would seem the backfeed could be an issue because of how freely it flows through the device.
Now back to the GG3 HUB device. One way to help get rid of the “S” kink in the rope path to improve ease of feed but still keep its function of preventing the rope from going behind the cam arm, is to grind away a good part of the rope guide tab to straighten out the rope path. The resulting path can be seen in the righthand photo at the beginning of the article.
By trimming the tab as shown below, enough of the tab can be cut off to straighten the rope path but still leaves enough so the rope can't get trapped behind the cam during a fall. I did it with a Dremmel tool and carbide grinding disk, it’s fairly easy to cut through the stainless steel material with a bit of patience and a steady hand. I held the Grigri in a vise while doing this. I then finished with a hand file and various grades of emery paper. I started off by first drilling a small hole to locate where the horizontal and vertical cuts would meet which also provided a nice radius for the transition between the two cuts. The end result may look sharp from the photos but all edges where the rope touches are well rounded. It also may look flimsy, but there’s still a significant amount of stainless steel and it barely makes contact with the rope as it slides past it while climbing. Also, during a fall, the force vector is away from the tab since the rope wraps around the cam away from the rope guide tab.
On a previous GG, I trimmed the tab down similarly but then fitted a stainless steel tube over it and filled the void with steel epoxy. While it looks a lot slicker and more professional, functionally it is not quite as good because the diameter of the tube impinges a bit more into the rope path and puts slightly more friction on the rope. On the same GG, in an earlier version of this mod, I fitted a small diameter roller bearing thinking that it would help reduce friction. However again, because of the diameter of the bearing, it impinged slightly more into the rope path and ended up with a bit more friction than this current mod. Sooo, that's it. The last of my holy trinity of GG mods.
As always, these are things I’ve done to modify my GG (and for a few friends). Do not try any of these mods without full knowledge and much experience, both lead rope soloing and with modifying equipment. You will void the warranty of the device; you could screw it up permanently so that it doesn’t function properly; and it could result in death.
Having said that, for me, it’s one of the best devices out there. For those of you wanting this functionality but don't want the risk of modifying a GG, once the rope creep bugs are worked out of the El Mudo (v3?), it will definitely be a simpler and safer way to obtain most of the same functionality that I've sought after with these GG mods. If you're a tinker, then the hopefully the info in the three blogposts will be informative.
Postscript: Since publishing this I’ve come up with another couple ways to totally eliminate the standard rope tab on the GG3 and GG+ but still be able to keep the rope from getting caught behind the cam arm.
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