I posted this last night on BROL in response to a question...so I figured I re-post it here since I get a lot of questions about neck rest models and available options.
"...here's the deal with the two shapes. The first neck rests I made were ROLL models. I used 2" thick open pore foam as fill. They were nice and people liked them...I really liked mine. Unfortunately the adhesive I was using caused the most amazing hallucinations and was probably what finally caused me to tattoo the note, "If I seem lost, please return me to..." on my hand.
I started making the CURVEs after I made a special order half-round neck rest for someone who needed to stabilize his neck side to side. The open pore foam fill didn't work well with the CURVEs so I began experimenting with latex...and began testing new less personally toxic adhesives. The latex was great, and I really preferred the CURVE design because I like how it cradles my neck. However I soon discovered the manufacturer couldn't control the latex density and so some batches I got were so soft they were unusable.
So I bit the bullet and started using memory foam, which is 3X as expensive as the other fills. Then I graduated from hand-made brackets to having them fabricated by a great shop in Portland and then powdercoated in Tacoma. And I finally discovered what seems to be the perfect adhesive.
Just about all my orders in the past 9 months have been for CURVEs, and the feedback has been terrific. I think that with the CURVE I've finally found the perfect combination of shape, fill type and adhesive.
As a result I've stopped making the ROLL model. And there's another reason. Memory foam seems happy folded into the CURVE but not happy wrapped around the ROLL base. It wants to return to its original flat shape. And because the adhesive works so well it becomes a tug of war between the two with the end result being that over time the memory foam seems to tear. While there are solutions they greatly increase the cost of making the ROLL. And since the CURVE works so well I just don't think it's worth the expense.
I've tried them both and I really love the CURVE.
By the way, I just sent off the first kit for a Trice Q and am anxiously waiting for feedback. And I have full kits available for Pockets, Trails and Villagers."
I'm really excited to see how the Trice kit works. It's essentially the same as the Catrike kit with one added shim to adapt the mtb stem to the smaller diameter horizontal seat tube.