I have a question which might be asked by honest people wanting to protect their bike from thieves, but unfortunately can also be asked by bike thieves. I hope this won't be downvoted, my intentions are entirely honest.
I have recognised a vulnerability in my bike-locking habits. I sometimes cycle to work into a commercial area with no residential buildings. This means that during the day, it's probably very hard to use an angle grinder to steal my bike (locked with a hardened steel U-lock into a solid bike stand). That would be noticed instantly because there are so many people working in these >10-story buildings in this highly dense area, and the thief wouldn't have enough time using such a tool making a huge noise.
However, I realized that using a battery powered hot glue gun, it's possible for a thief to quickly prevent me from opening my lock, with absolutely no noise, in just two or three seconds. Then the thief can steal the bike with a battery powered angle grinder, during the next night, when practically nobody is present in this commercial area (there are no residential buildings there).
Another way for the bike thief to immobilize the bike would be to add a secondary lock, that the bike thief owns, with me having no key for that lock.
Previously, I wouldn't have any defense against this kind of quite clever attack. However, recently I bought a battery powered angle grinder for sharpening lawnmower blades, and I recognised if I notice this kind of attack, I could quickly take a taxi home, get the angle grinder with cutting wheels of the proper type and count (in case I need more than one wheel) plus receipt as proof that I'm the owner of the bike (in case the police notices me using the angle grinder against my bike U-lock), and drive to work by car immediately to save my bike by cutting the lock before the thief does it. However, to be prepared against this kind of attack, I need to buy some cutting wheels, of the correct specifications, and enough many that I can be certain to cut my lock with it.
The hardware store sells these kinds of cutting wheels compatible with my battery angle grinder (I listed only wheels made for metals, there are some wheels intended for cutting rock that probably aren't applicable):
- 1.0 mm, 125 mm, for steel or stainless steel, 1.49 EUR (so cheap I already decided I'll buy few)
- 1.6 mm, 125 mm, for steel or stainless steel, 1.49 EUR (so cheap I already decided I'll buy few)
- 2.5 mm, 125 mm, for metals, 1.49 EUR (so cheap I already decided I'll buy few)
- 1.4 mm, 125 mm, diamond, for metals, 14.90 EUR
Which and how many of these would be the best choice to be certain I can cut my bike lock before the thief does that after disabling the lock with glue? I need to buy them in advance as any delay in buying them as-needed would give the bike thief more time.
Are the standard non-diamond wheels hopeless against hardened U-lock shackles? Should I have the expensive diamond wheel for cutting through an U-lock, and if so, how many diamond wheels are expected to be required?
The lock is Kryptonite Evolution Mini 5. But then again, a bike thief can disable a bike by putting an even more hefty secondary lock, so I may need to be prepared to cut through the Mini 5 plus another lock that's the most secure U-lock out there.