Fall out of cart going uphill

When going up a hill in a minecart and pressing forward (to make the minecart move) makes you fall out of the cart.

I have a spiraling track to get up from bedrock to my house with a single unpowered rail then straight away powered rails going uphill, so I have to start myself moving then very quickly let go of the forward button or I fall out straight away. Pressing forward while going either downhill or just of flat works fine.

Using a HTC Desire C