Recently, when I cycled my bike the pedals would jump when I pushed down on them. I brought it to a shop who replaced the cassette, the chain, the two crank arms and probably the crankset. I have also had the rear gears replaced.
All great for about 15k, till the pedals started to jump again, when I pushed down. Thought it was sth to do with freewheeling/backpedalling when coming up to lights (as is particuarly bad when I stop/start) but that is not always the case. Also, the pedals spin when I push the bike forward - again, this is intermittent.
Have had it into the shop about 5 times, to no avail. Am lost. Bike is only about 7 years old. Anyone able to help please?!?!!