Basically I have been doing whiplashes for years now and never had a problem but 2 days ago every time I do one my cranks turn like half a crank mid wiplash , it's so annoying , I usually ride a really lose chain and I know if I tighten it , it might solve the problem but I do a lot of crank flips so I don't won't to really, anyone have an idea what the problem is ? ( and I have a promo freemix if that's any help