I have a knocking sound that occurs about once every rotation of the pedals. I have to be riding the bike and pedaling for it to happen. The sound can't be reproduced with the bike on a work stand. I've replaced the Bottom bracket spindle and bearings, cranks, pedals, chain, rear derailleur and rear wheel. The only thing left is bearing cups, I'm going to changes those in the morning. I think it's coming from the bottom bracket area, but it's hard to tell for sure while riding. Any suggestions.

Thanks