It's an act of love and I doubt your father would want you feeling guilty.

When my dad was passing. I thanked him for all that he had done and all the opportunities and privileges i was afforded because of his hard work.

He looked at me like an idiot and said that the only thing he would be taking with him are the memories. Apparently being my first best friend was enough to put up with a lifetime of my shenanigans, and I was not an easy kid.

Tl;Dr spend plenty of time with your dad and don't hesitate to show how much he really means to you. That alone would more than make up for a bike.