OP, you've been deservedly harangued enough about your choice of descriptive words for your mom. But, as I consider my own mom, no longer with us, on Mother's Day, I found them an abrasive, kid-thing to indulge in. Hopefully, by the time your age permits you to join us, such things will just naturally be objectionable to you, too.

Nice thing you're doing in buying your mom a bike. There's hope for you I think. Give your mom a full stake in her new bike, by taking her down and letting her make some of her own choices and even ride a few. Most 67plus year olds I know are vitally interested in life, in making their own choices, and keeping or expanding their own identity. They're even interested in learning new things! Let us know how things turn out. You seem a promising enough BF'er.

["Kids" always hate being patronized by those older, wiser, more experienced, etc...which is undoubtedly us, right guys?!]