We couldn't find anyone who cycled up but we can confirm that it is possible. Although we parked our bikes 3km before the end and walked the last bit. We left our heavy stuff in Sisian and managed to go up and down in one long day. Grassy and sometimes rocky path with several stretches that go up 10-14%. We managed to stay on our bikes for most of it but sometimes had to push our bikes. The whole journey and the scenery on top are stunning. A real adventure.