Here's how I can take a bass on my two wheelchairs. One wheelchair is electric ; the other is acoustic. The gig bag straps thread over the top of the electric wheelchair's backrest and down behind it. The other wheelchair doesn't have the right backrest for that. The net and straps shown are a pannier made for taking guitars on the back of wheelchairs. It's adapted from one made for taking guitars on cycles. I already had a cycle one, before I needed a wheelchair, and asked the maker to adapt the design for me.