The exact issue is important. You said "jumper's knee," which involves only the patellar tendon, with pain noticed particularly below the patella. If the pain is not below, but is to the inside or outside of the patella, that's a completely different thing. However it you are indeed experiencing patellar tendinopathy, this is the best article on rehab I've seen:
https://www.strongerbyscience.com/sq...-tendinopathy/
I recommend staying off the bike and just doing these exercises. This is something which has to be rehabbed now.
Pain to either side of the patella is not tendinopathy, bur rather muscular imbalance.