bike pedals

[unicorn]

why are bike pedals fitted left and right hand thread

[beckyboo]

To stop them unscrewing when riding

[ChuckFickens]

Yep, anything that has a rotational movement that may unscrew it in use should be fitted using a left hand thread so it naturally tightens in use rather than loosens.

[Graham-W]

My old Transit van had left hand thread wheel nuts on one side for exactly the same reason. How much fun did I have the first time I needed to change a wheel for the first time on that side?

[heathfield]

Some more sporty cars used to have their wheels held on with a big single hub nut. These were always left hand thread on the passenger side for the reason Chuck states.

[bert_h]

Heathfield, did that mean that if you reversed too quickly, all the wheels would fall off? !!