okay, i'm terrible explaining things, especially bikes since i'm not an expert about mechanical shtuff so i'll try my best...please bear with me!
when i'm riding on a flat road or at a moderate speed there's some resistance to the pedals which actually makes me be able to pedal but whenever i'm pedaling fast or going downhill, at some point my pedals just kind of top out / stop :working: (??) and although i may pedal, it feels like i'm just spinning them but i can't go any faster. the feeling is almost similar to being in a low gear on a flat surface. for example, the other day i was going pretty fast downhill and when the road flattened out the speed from going downhill was still with me but my pedalling had no effect, so i basically had to wait till i'd lost speed from the hill to be able to start "really" pedalling again and at this point i felt like i was going really slow
is this normal? how can i change this? it's really frustrating!!