TT, It's possible to bonk in three hrs or less doing low intensity ride/run. IMHO it's related to how much glycogen that is stored prior to the training and how much you replace it during.
I bonked 1:55 into my 20mi marathon training run. I think largely because the night before I only ate a grilled grouper salad. Not alot of carbs in that!!!! I ate on my run every 45min. drank gatoraid at the same time but I still bonked. I am glad I had gels with me or I would have been in bad shape. I know I never want to do it again, the marathon was a piece of cake compared to that run.
I bonked 1:55 into my 20mi marathon training run. I think largely because the night before I only ate a grilled grouper salad. Not alot of carbs in that!!!! I ate on my run every 45min. drank gatoraid at the same time but I still bonked. I am glad I had gels with me or I would have been in bad shape. I know I never want to do it again, the marathon was a piece of cake compared to that run.