Bishop to Onion Valley would include the 40-mile section south on the 395, then 13 miles climbing over 5000 vertical feet to Onion Valley.

It would take some conditioning and training, but you can probably do it. When I was at Whitney Portal, a guy on a bike rode up. I asked him and he said he had ridden up from Lone Pine. The climb to Onion Valley ends a little higher than Whitney Portal.

Good luck!