SauRoNZA
Honorary Master
I'm assuming that it is at least to some degree spring loaded, so its applying pressure.
I've considered getting a handlebar bag for this exact use case though - just don't trust the average Saffa to not want to steal the bag off my bike - having had my car broken into 3 fscking times this year.
Rather get the bolt-into place tank bag jobs like SW Motech and others sell.
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https://sw-motech.com/en/products/luggage/tank+bags/ION+tank+ring/
https://sw-motech.com/en/products/luggage/tank+bags/ION+tank+bag/
