The VAR Super-Tyre Tool (British import) weighs next to nothing. It fits easily in a small seat-bag or pocket. And it makes getting super-tight clinchers on/off the rims a breeze. A larger one is the Kool Stop Tire-Jack - which is really too big to carry - works on the same Archimedes principle.

I suggest that if you purchase, copy down the instructions on the seller's website. The guy is honest and fast - no worry buying from him.

http://cgi.ebay.com/VAR-Super-Tyre-T...4.c0.m14.l1262