Recent victim of bike theft in Chicago and replacing $700 bike. Received lock recommendation - Kryptonite Kryptolok Series 2 Std. Bicycle U-Lock (4x9) with 4-foot flex cable. Reside in suburbs, but occasionally go into Chgo with bike left unattended for hours while at museum, shopping, or restaurant. After theft, considering Kryptonite New York Std for security (overkill?), but comments suggest lock is very heavy. Any suggestions on locks that provide strong security, but also easy to carry. Even once, no one likes to be the victim, certainly don't want it to be twice.