For machines with cloth cage rim covering, it's extremely helpful to put smooth tubing around the hoop. This includes the Blackhawk suitcase model, Skycruisers, Paracruisers, Phantom, Miniplane, ZG Cruiser and others. Tubing allows the lines to come up cleanly around the cage during forward inflations. It can make a dramatic difference in your no-wind success rate while also protecting the paraglider lines from wearing on the hoop. Paraglider repair shops have reported this wear and I've noticed it myself (I fly mostly with these types of cages).

The best tubing I've found was used on Kenny Carlock's Sky Cruiser. It's from www.McMasterCarr.com, Item 52315K251, an extreme-temperature tubing made with PTFE (Polytetrafluoroethylene), 5/8" ID, 11/16" OD, 1/32" wall thickness. This unreinforced tubing is opaque black and comes in 2, 5, 10 or 25 foot lengths.

A cheaper alternative, available from Ace Hardware (among others), is 3/4" water tubing. It's translucent white, a bit heavier, but works pretty good.

You can easily slice the tube using a razor stuck into a piece of PVC pipe at an angle. Slide the tubing through the PVC to carefully cut so the slit on the tubing's natural inside curve. Snap the tubing around the rim and secure with electrical tape. It doesn't need to go all around the cage but cover at least 2/3's of the rim from the bottom.

Cage hoops with fabric tend to snag lines like in photo 1--putting smooth tubing around the fabric solves the problem. The white translucent tube shown in photo 2 is cheaper but a bit heavier and not quite as slippery as the good stuff shown in photo 3 (Kenny Carlock launching).