a five-foot long self-clamping sawing guide
Ah, well, that explains it
To fix such things to a bicycle, there's another trick device I'd recommend--maybe complementing, rather than replacing the Knotbone Bungee:
This Quick-Release rubber tie [
http://www.leevalley.com/en/garden/page.aspx?p=65393&cat=2,43319,33283 ] can go around your sawing guide (I think), locking the item to your top tube, and maybe your downtube as well, depending on the angle from the horizontal. Depending on the vertical height of your guide, you might need the 8" or the 12" QR tie.
These things are also essential items for my workshop/camping/etc gear.
Mind you, the catastrophe linked to the sawing guide is surely a Thing Of The Past -- after all, you're not likely to get another one, are you? In a sense, both adjustable bungee and trick QR ties are tools for fighting the last war. That said, buy the sample pack of 10, and you'll wonder how you managed to get this far in life without these little critters.