I wouldn't lock my bike to a radiator pipe, as you could come home to find no bike plus a flood.
A wall anchor as suggested above is the best bet. However, I use a couple of RawlBolt /Shield anchor eyelets (the better quality ones with an unbroken eyelet) as a locking point for a boat trailer. I have the padlock through both of them so they can't be unscrewed.
I wouldn't lock my bike to a radiator pipe, as you could come home to find no bike plus a flood.
A wall anchor as suggested above is the best bet. However, I use a couple of RawlBolt /Shield anchor eyelets (the better quality ones with an unbroken eyelet) as a locking point for a boat trailer. I have the padlock through both of them so they can't be unscrewed.