A good standard for endurance sports

I was recently talking to my uncle about the sort of achievements that would be good to achieve as a semi-competitive age-grouper. That is, you're not new to the sport, but also not in an elite category. In the end, we decided a time 1.5x slower than the elite record is generally a good benchmark. That gives the following (for men):

• 5km - 18:56
• 10km - 39:26
• Half marathon - 1:27:27
• Marathon - 3:02:28