I used to double shift all the time with my STI levers. Don't do it any more with my friction shifting. When my freewheel seized up I wound the RD around the rear axle similar to this, but it stayed out of the wheel. I shortened the chain to make it a single speed and it held up nicely for the ride home, and another 1200 km beyond that once I put the extra links back in to fit the new RD. Always carry a chain tool. A few links would be nice too.