I have a loose Shimano 105 8500 shifter blade. How do I tighten them?
I'm not sure what you mean by "shifter blade", but I might assume it might be the cage of the derailleur. On the front derailleur there is either a rivet or a small bolt at the trailing edge that holds the two halves together, if it is a rivet then it is not repairable and the derailleur will need to be replaced, if it is the bolt, it is probably a 8mm socket head, tighten to the right. If it keeps loosening up from road vibration then the threads could be stripped (replace the derailleur), or else put a drop of Blue Loctite on the threads to prevent it from backing out. If you are talking about the rear derailleur cage that holds the two pulleys in place, these have two Allen type bolts, probably 3mm or 4mm Allen wrench size. The bolt slides through a small bushing inside the plastic pulley wheel, the bushing is slightly wider then the pulley to prevent over tightening the cage plates against the pulley, thus preventing the pulley from spinning freely, use the Blue Loctite if the bolts keep coming loose. Blue Loctite (also known as 242 Loctite I believe) is the removable type and provides some extra friction to prevent bolts from backing out. Now if by "shifter blade" you are referring to the shift/brake levers, these have a small amount of "play" in them from the factory, a little bit of wiggle. They basically are not serviceable. Try adjusting the derailleur cable to see if that removes excess play. If they still have an excessive amount of play in them, then you will need to replace the shift/brake levers as a unit. If you do this, make sure you get the shifter that is designed for the number of cogs you have in your gear cluster and front chain rings. I would recommend also replacing your chain and rear cluster at the same time so that all part wear evenly for optimal shifting performance.