Beware of inner tubes. They can leave black marks and can discolor glue that touches them.

Hi Malcolm,
I've used bicycle inner tubes as clamps in non-kayak situations needing odd clamping. If you slice them into two strips, the forces are much lower. Wash them first, stretch them out flat and use the talc/chalk that comes with a tube repair kit to lightly dust the strips. Then give them a wee polish, a rub of a cloth as it were, and they're ready to use with no black marking. The talc doesn't seem to come off the tube onto timber for some reason.
Sounds a bit long-winded but you only need to do it once.
@ BillH
When polished with bike repair talc, glue doesn't stick to the tubing. Not sure about epoxy, haven't used the two at the same time yet.

Try latex surgical tubing. It's the same stuff they use in slingshots!

A wee warning with latex. Some are allergic to it, and you can develop an allergy to it if you're sensitive to latex. It is similar to epoxy in that aspect.

Mike Savage
South West Cork