Tough, lightweight steel U-lock with narrow dimensions provides security in high crime areas for road or mountain bikes. Narrower space within the "U" and shorter length crossbar makes it harder for thieves to get their tools inside. Patented deadbolt lock mechanism on bottom (instead of side) is easy to access but difficult to break into. Small, tubular keyway is difficult to pick. Krytonium(TM) steel provides superior strength without added weight.