Ariharry

Michelle, thanks for the recommendation, I'll tell my grandfather. I will try to keep track of his nutrition

Karen_L, I appreciate your detailed reply. So good to know that cycling brings you joy. I will definitely try your tips!

Hi AriHarry,
I'm an avid cyclist and have been for most of my life. 
Hills can definitely impact knees, but how you ride the hills is what makes the difference.
How you pedal can affects which muscles your lower body responds with. A grinding pace-- slow cadence (turning of the pedals) and high resistance (the feeling of load you are pushing against) calls on your leg muscles, especially your quadriceps, to carry most of the burden. Knees don't love that. If you shift into gears that make it easier to pedal, it will lighten the load on your knees, asking more of your cardio system.  
There's a lot of information on the web about how beginners can learn to cycle up hills. First, though, you have to find a bike you like. My biggest recommendation, if your budget allows, is to go to a reputable bicycling store. A good one can listen carefully to what you are looking for, help you find the right size, and get you outfitted with the essentials: A HELMET. E-bikes often are typically sold by specialty stores. 
You may need to invest some time exploring and testing bikes-- a good bike store will let you ride whatever bike you think might interest you. If they don't, that's probably a red flag about their expertise and service.
I just did a quick search and found a couple of resources that might help you. 
How to start cycling-- everything you need to know It talks about everything, even the kinds of bikes there are. 
The 12 Best Beginner Bikes for Adults and How to Find Your Perfect Fit  at the Livestrong site is helpful. Livestrong was started by cancer survivor Lance Armstrong. He's not affiliated with the site any more, but it's a great resource.  
Bicycling Magazine is also good for an overview on bikes
If riding on the road is concerning for you, perhaps a stationary bike would be good? Lots of people like to watch a movie or listen to books as they ride. That involves a different type of research-- bike stores don't carry those.
Just take your time so you get what is right for you.
I wish you a lot of luck. Bicycling brings joy to my life. I hope it will for you, too.

My grandfather adore Margherita!

Thank you for this post! Interested in riding a bike: can a difficult road affect the condition of the knees? For example, if the road goes up? This is quite difficult to do even for a healthy person. And what kind of bike is the most preferable - gravel or road or even electric bike? Thank you!

Thank you for this post! Interested in riding a bike: can a difficult road affect the condition of the knees? For example, if the road goes up? This is quite difficult to do even for a healthy person. And what kind of bike is the most preferable - gravel or road or even electric bike? Thank you!

My grandfather adore Margherita!

Great poem! Sure it can give the strength to fight with the cancer

Ariharry,
Sorry to hear about your grandfather's condition.  Please take a look at our Caregiver Resource Center as there is information there that can help you in your role as someone looking out for a relative.  Please let us know if there is some other information you may need.
Lou

Hi. My grandfather is a smoker for over 40 years, and the cancer still appeared. About 10 years ago, he had a complicated heart surgery, after which he felt better. Two years ago, he had pneumonia with 25% lung damage, but he successfully coped with it. Now he has severe circulatory problems. I'm afraid for him, I really want to support him, but I don't know how not ot to show him my fear. I really hope that we can forget cancer like a bad dream, and he will feel better. We help him with the whole family to cope with this, but still it is hard for us to realize that he has such a diagnosis. He is a real fighter, and I am sure that he will be OK soon. I wish everyone to recover from this terrible disease and never face it again!

Hi. My grandfather is a smoker for over 40 years, and the cancer still appeared. About 10 years ago, he had a complicated heart surgery, after which he felt better. Two years ago, he had pneumonia with 25% lung damage, but he successfully coped with it. Now he has severe circulatory problems. I'm afraid for him, I really want to support him, but I don't know how not ot to show him my fear. I really hope that we can forget cancer like a bad dream, and he will feel better. We help him with the whole family to cope with this, but still it is hard for us to realize that he has such a diagnosis. He is a real fighter, and I am sure that he will be OK soon. I wish everyone to recover from this terrible disease and never face it again!