riding back home last night a few times I had the bike make this really weird choppy noise. sort of like a krrrrrrrr metallic noise of something being unwound or ground down. Once on up-shifting it happened and my revs shot up a little and I think it got stuck. Upshifted a few moments after this no problem. Later when downshifting same thing happened. Could it be me downshifting too quickly in this case? is this a compression lockup? I possibly did something wrong when upshifting as I've put myself in neutral before (while riding) by mistake. Any ideas?