Maybe this is common knowledge to other Brompton riders but it came as a surprise to me the other day,just thought I would pass the info on.
I ride a Brompton H 6spd with a rear rack and four eazy wheels. I had a rear flat ,recently,five miles from home.No big deal just folded the the bike up, leaving the handle bars and seat up to push it home just like in the supermarket.Pushed it about two feet and it stopped dead with a loud clunking noise.Checked it out ,couldn't find anything wrong and tried it again with same result.After some experimenting I discovered I could only make it go by tilting the bike back onto the rear two easy wheels.Baffled I continued to push it that way for a few blocks and stopped to rest at a bus stop.While sitting there I looked the bike over and realized the rear tire when inflated and folded back under supports the rest of the bike and holds the bike higher off the ground than if the rear tire is flat.
With a flat rear tire , rear rack and easy wheels, the front wheel is in contact with the pavement and turns as you push the bike makeing the wheel wiggle back and forth just enough to catch the spokes on the end of rear gear hub where the control cable goes in.
It took a few more minutes to figure out that in order to fix the problem it needed something between the top of the rear rim and the upper frame to hold the bike to it's proper height.I took off my sweater, folded it up and squeezed it between the frame and the tire.It then could be pushed normaly on the four rack wheels again.and was a lot easier than tilting the bike back on the back two wheels.
I would be interested to see if anyone else had this experience,and think it should be passed on to other Brompton riders.