Chain and padlock is definitely the cheapest option, the local dollar store might even have one pre-wrapped and sold for bikes specifically so it won’t scratch your frame. Mine does for ~$15.
They’re harder than U-Locks to cut through anyway because they’re hard to hold still for the angle grinder, just make sure you use one that’s thick enough.
I use a motorcycle chain that I found abandoned and a truck padlock, never had a problem in 4 years. It’s heavy though, at least 10lbs.
Chain and padlock is definitely the cheapest option, the local dollar store might even have one pre-wrapped and sold for bikes specifically so it won’t scratch your frame. Mine does for ~$15.
They’re harder than U-Locks to cut through anyway because they’re hard to hold still for the angle grinder, just make sure you use one that’s thick enough.
I use a motorcycle chain that I found abandoned and a truck padlock, never had a problem in 4 years. It’s heavy though, at least 10lbs.