Yes Brother it is enough
No, it's way too little. And running with bike is a horrible idea because of the joints. Your dog may start to misbehave because of lack of exercise and the once a week bike run will most likely ruin its joints.
You may want to talk with your vet about this because depending on the age and sex different dogs need different amounts of exercise.
I have 2 GS and both about 4 hours per day outside running and playing. Both are trim and fit but I would bet that would go more If I could. They seem to be wore out by the end of the day however because they sleep when I do. They may be testing me. What I would say is they would probably play as much as you can. As long as they are not over weight and do not display bad habits such as a dog would if he were board or felt neglected he is probably OK. But as stated before it would depend on age and other activities that he would be exposed to on a weekly bases also. Have ahim checked out at the vet and ask the vet the same question.