bike lock cable
 

We have a 4-bike rack for our car. I'm going to get a threadable locking hinge pin but I also want a lockable cable. My question is how long should the cable be? I see 6.5, 8.5 and 10 foot lengths. Is longer better? Or more than needed. Thanks in advance.

Why not take a piece of rope or string and simulate how'd you lock all four bikes? Then measure it and decide for yourself.

Personally I'd just get the long cable, if only because you might want to use it for something else later.

I'm usually carrying 2 singles or a tandem and a single. I use a 10mm diameter steel cable 10' long which I loop through the wheels and frames. I use a master discus padlock to secure. Thieves can cut the cable but they still have to spend a little time un-threading the lock cable from the bikes before they can get away with the bikes.