For my teams climber we are using a tape measure to deliver a cable to the bar. During this period we would like the spool the cable is on to freely spin to allow as much cable as needed without having to perfectly time two motors together (one to get tape measure up one to get the cable up). All the ones I have seen are a couple hundred dollars. Are there any that I may be able to find cheaper?

A few hundred dollars is the going rate for COTS shifters.

Is there a reason you need to spool out the cable rather than starting the cable with enough slack to reach the bar, and only winching it in on a ratchet rather than motoring in both directions? This was a common solution for teams in 2016, many used tape, cable guides or velcro to manage the slack cable until it was time to climb.

This method has the added benefit of not requiring the tape measure to be able to unspool the cable. Even with the motors disconnected, pulling against a spool with some gears attached is a non-trivial amount of force, and is likely to collapse your tape measure.

Agreed. Lay the cable out in a figure eight pattern to cancel out the twists as it is lifted.

You should have some system to keep the cable secure until you’re ready to reach for the rung. This might be a servo, small pneumatic cylinder, or latch released by the action of the tape measure motor to keep the cable secure (at the crossing point of the 8 is a great spot for this). Otherwise, you’d likely violate G05 and risk violating G10, G11, G19f, and likely a few other rules.

Check out a flaking box to manage the cable/line. Here is wiki page with a picture. Lyle gun - Wikipedia


In 2016 we carefully stored the extra cord for our climber in a racquet ball with a slot cut in it. The ball was then attached to the frame. when we deployed our climber mechanism the slack was bulled out of the ball without tangles. This resulted in a trouble-free solution to the “how do you store the slack?” question.