Back in 2000, I had sciatica due to a ruptured L4/L5 disc(down my right leg) but never had any weakness or trouble going down steps. Now, I wasn't riding a bike then so I have no idea about any problem with that or balance with a bike. That bout of sciatica was taken care of, after 6 months of meds/ PT/rounds with the insurance, with surgery--a lumbar laminectomy. It's the stumbling/leg buckling on the steps and trouble mounting the bike and standing while riding that has the doc, and myself, concerned.