I need something to protect the down tube on my bike.

Was thinking about a thick piece of helicopter tape but not sure where to get it from.

Is there anything else to consider ?

I cut a length out of an old tyre and ziptied it to the down tube to protect from rock strikes. It’s not elegant but it works.

I’ve just bought some tesa tape from here

Fairly cheap, loads of different thicknesses available and went on lovely.

This tape from Aldi @ £2.99. Cheap enough to build up to whatever thickness https://www.aldi.co.uk/en/specialbuys/thursday-13th-march/product-detail/ps/p/all-weather-tape/

Shelter tape

Pop roundtable to your Local Car wrapping Business and get some 3M DiNoc offcuts….