I was re-reading an old "tech tip" from a Climbing back issue: The author of the tip was advocating pulling along a static 7mm (yes, SEVEN) tag line (60-65 meters long) to use for full-length raps with the lead line AND to bail-off mid-lead by rapping the thin cord, off your top piece of pro', while being belayed on the lead line through the pro' below, cleaning all but the top piece as you descend. This sounds like a good way to get out of an uncomfortable spot, if you find yourself "in over your head". I started shopping around. Thing is Bluewater sells a 9mm static line--but they don't advocate using it for rappeling. Anyone have experience with this technique? What kind of skinny cord have you used?

Most any EMS, REI or other climbing store carries this for making cordelettes. If they don't have a long enough piece you can get one within days.

try practicing aid climbing instead of bailing. some places you just don't want to bail off of like black canyon

Cough... Cough... Doubles... Cough...

For certain situations, I have a Beal 8mm static. It's also very handy for many of our canyons, where many of the raps are in the 30' - 60' range.

Your not going to use a tag line on short routes, so if you are on long routes doubles are certainly a better way to go. If you are going to deal with having a second rope you may as well use it to make your life easier while climbing. A set of double 8.5 mil ropes will probably weigh the same as a 10mil single and 7 mil tag line. Double make protecting a route easier and safer as well as then having ropes of equal diameter to rap with. I only use a single on longer routes when I know that I won't be retreating, the route is a topout/walkoff and speed is an issue.

I should have said that a tag line is really only used for aid climbs where a beefy single rope is needed as a primary.

Most experienced climbers have adopted a system that works for them. I prefer to lead on 9.4 to 9.8 and tag a 6mm. You can use it for double rope repels and hauling extra gear on lead as well as food and water on long climbs. A tag line is a useful tool wether free climbing or aiding. There is only one 6mm I will use and it is marketed as The Personal Escape by Esprit out of Canada. You would need to call them to order it. You say 6mm. Yes it's safe to about 1700 lbs. and it's light. Have personally done single rope repels, a bit spooky at first. The thing is more like a cable and wears like iron. Many people will surely disagree with me but this system works for me. Also tagging an extra line gives me the option of having 2 ropes should something happen to the lead line. I recommend cking out their site.

I use the tag line and my 9.4mm rope when I know I'm going to be taking a lot of whippers on my gear (I'll do a lot of routes in the 5-12pitch range where I know that I'll be taking whippers working out the moves). I wear out my 8.5mm ropes (usually for ice climbing), I don't need to destroy them in the summer on long routes.

If i'm really anal about weight then I'll go with a 8.9mm or 9.0mm single line (and not so concerned about the expense of destroying ropes)and a 6-7mm tagline, making for easier organization.