I was riding home from work mid September on my Giant in and the rear wheel was rubbing. A quick glance when I got home suggested that it needed a little truing so I swapped back the original heavy duty Giant wheels and thought nothing more of it. This weekend I thought I'd spend a little while trying to pull it back to true and spotted this:
This is a pretty catastrophic failure - I was lucky I swapped the wheels when I did as this would have been a ride stopping failure!
I have started to strip the wheel down (to keep the hub for general bike maintenance purposes) and have seen another crack in the rim. The front looks OK but I'll double check now.
The wheels have done about 12500 miles - mainly in the Spring to Autumn months. I don't think that's particularly impressive, given that I am also quite light.
Update 4 November: I have scrapped the rims. I cut them up and here is a couple of shots of the cross section:
