RM, I don't think you said anything wrong. I hear your frustration! We all talk to parents that way some time, jeez... Now i'm not in that situation, since my mom died almost 11 years ago. If she was here, she WOULD be out riding, even if it was on a crappy bike. She was very athletic and fitness oriented and walked 5 miles a day until she got liver disease. I think you just wished your parents would have waited and taken advice from you, because that means they value your opinion and even see you as an "expert" about bikes. Some parents just can't do that (like my husband's). I know that my adult children know a lot more than me about certain things and I definitely take their advice. On the other hand, I don't give any to them, unless it is asked for! Thankfully, they do ask because I have worked very hard to keep the lines of communication open.
So, I wouldn't feel too bad about what you said to them. As for the honey vs. vinegar thing, I can only do that so much, more in a work situation than with relatives. I guess I am not a "honey" type of person, being the mean, Northeast US person that I am! I totally understand where you are coming from.