I've never really soloed anything
significant. Climbing with a partner is much more fun.
I do,
however, use solo systems quite a bit for speed climbing - or at least I used
to...
The drill I used was 5/32". Cord is 3-4 mm; whatever you can shove through the hole. The hole placement was right in the bottom v-notch of the "N" in "ONLY" stamped on the Gri-Gri. The hole is a stress riser, so you don't want to drill it too close to the pin. Countersink and clean hole with a jeweler's file.
Next, I sawed off the flap. I then used a sander, file and buffer to finish. The result is round and flush with the rest of the metal. I also buffed out other areas that might catch on the rope.
This is probably the best soloist available because of cost, reliability, weight, ability to lower off without re-rigging, and ability to use on aid or free because of rope feeding. Some claim that this device will catch an inverted fall, but I am not so confident myself based on some simple tests I have done. The 3mm cord used and the requirement of a chest harness seem to make the catch of an inverted fall even less predictable. Caveat Emptor! I attach the Gri-Gri to my harness via a standard Munter biner. The top of the Gri-Gri is attached to a chest sling via a simple Light-D biner. I feel the Gri-Gri is more likely to lock during a variety of falls if it is only attached to the Munter biner alone, like a Solo-Aid device. Using some sort of break-away like a velcro loop between the device and a chest harness may help the Gri-Gri orient properly during an inverted fall.
Another popular way to modify it is to install a metal swaged cable loop instead of the 3-4mm cord. Basically start your hole in the same location ( the "N" in "ONLY" ) but drill a straight, through-all hole. A clearance will need to be cut into the opposite plate so that it will still open and shut. Install a small swaged cable loop through the hole.
This mod. may effect how the device orients on your harness rig, perhaps providing an advantage in that way. Some feel there is more strength with this method. I think the cable would cut all the way through the plastic portion of the Gri-Gri, providing little if any strength advantage in that way. The cable may hold the hole better, but the cord cutting may be an advantage in a hard fall, allowing the device to orient properly. No testing has been done, and I doubt there ever will be. Basically, I think it is personal preference and a bit of hypothesizing.
I have also heard of people cutting off the plastic handle. The handle has been a good thing for me. I see no advantage in cutting it off.
If I can offer any useful testimony, I have used this device on about a dozen speed ascents. I am more comfortable with it than anything else I have used, including the Soloist and Solo-Aid.
If you don't understand something here, then you should probably not consider this modification. Modifying gear voids the warranty and, according to the UCC, releases the manufacturer from liability. You could wind up dying a miserable, gruesome death due to your own fallibility.
- NB 8/95
NB 7/1999:
Note: I now believe that a clove hitch on a munter biner is the
best, safest method for soloing. This page is only here for
reference. In fact, I wouldn't use a Gri-Gri for anything but long
aid belays and rapping single fixed lines. As for the Silent
Partner, I think I would wait a few years for the techie climbers to "test" its
safety..