Folding bikes are lower to the ground than big wheel models. This causes an increased risk of ground strikes with pedals. Sharp turns lean the bike at a larger angle, bringing the pedals closer to the ground. Additionally, unlevel roads can create additional road risk, since the road at your pedal maybe higher than the level at the tires. To mitigate this risk, we use high bottom brackets, but it still happens....we can't control the roads. Please be careful of ground strikes, they can cause  a rider to lose control of their bike.