A ropewalking rig can save a lot of physical effort, but is really only worthwhile for longer pitches...
For a couple of years i've been experimenting with various bungee ropewalker rigs.
Rig 1 - ropewalking with no chest roller
This is similar to a standard Frog SRT rig with a Pantin on the right foot, the upper ascender (Petzl Basic) moved down below the croll, with the footloop on the left foot clipped directly to the ascender. The ascender is pulled up with a thin bungee cord over the shoulder. This setup can be converted back to a standard frog SRT rig in about 4 seconds.
However, because of the effort needed to keep upright, this uses just as much energy as a standard frog rig (ascending while leaning back away from the rope is tiring and wastes a lot of effort). To keep upright when ropewalking, a chest roller is essential. These are not available in the UK and a PMI single chest roller imported from the States costs about $200 + duty.
A DIY solution was needed.
Rig 2 - small chest roller
The original idea came from Clinton Elmore's DIY chest roller on YouTube:
An eye bolt from Screwfix and a nylon "dirt bike chain tensioner roller" from ebay made something very similar. The nylon roller ran on a 10mm copper solder coupling acting as a sleeve bearing:
This worked fairly well and seems slightly more efficient than prussiking using the frog system.
Rig 3 - chest roller with attachment points further apart
The eye bolt wasn't long enough - this created a steep angle where the chest harness clips to the bolt. This meant the chest harness had to be extremely tight to hold me close to the rope.
The harness really needed to attach to the chest roller at 90 degrees either side. This minimises the tension in the chest harness.
The 190mm eye bolt was replaced with a 250mm length of M10 threaded rod. This has a drilled aluminium angle at each end to hook onto the harness.
The sleeve bearing is now a pair of drawn cup needle bearings from Bearing Shop UK: HK1012 (id 10mm, od: 14mm, width 12mm)
The nylon roller is 24mm wide, so you need 2 bearings, but they're only about £1.50 each.
The roller was drilled out to 14mm and the bearings are a tight press fit.
The bearings are packed with lithium grease and run on top of the thread:
Changing back to a standard frog rig mid-rope takes about 5 seconds. A cord prevents the chest roller dropping down the pitch when detached. The length of the hooks have since been reduced to make it easier to attach and remove.
Shopping list (total about £20):
- 250mm 10mm threaded rod
- 2x 10mm washers
- 4x 10mm nylock nuts
- 2x HK1012 bearings
- chain tensioner roller
- two drilled aluminium strips 20x3x50mm for the hooks
- 14mm HSS reduced shank drill bit