Denver's bikes have locks

They have a built in cable that allows you to wrap it around something, and once you insert the cable into the side of the basket, a key pops out. $10 fee for loss of key.

Denver's bikes also have GPS and can be tracked from B-Cycle headquarters.

No deposit here, but you get charged $1,000 if the bike isn't returned in 72 hours.

I am jealous of Minneapolis' system though. There appears to be more stations, more bikes and above all, your infrastructure is better.