After this morning's ride, I can tell you that an energy gel sachet lasts about a mile and half. After the first blowout, we noticed another bubble of inner tube so he had two boots in there. That tyre should have been binned months ago!
Why do people ride ultra-expensive carbon race bikes in winter, subject them to a shocking lack of maintenance and won't spend £15 on a tyre when the old one is clearly falling apart?