7700 STI won't downshift

[victorduraace]

Hi! what's the remedy for right Dura Ace 7700 STI that requires to be held still and only then will downshift...
I heard of air blasting and WD40 but it doesn't work
thanks

[Stolichnaya]

You sure this is not a cable friction issue? Have you checked that the cable routing is smooth, tension is proper and that the cables and housing are playing nice with each other?

[eric]

Make sure the cable has not frayed. That normally happens inside the shifter.

The grease that Shimano uses tends to harden and gum up the shifter. That makes the mechanism not catch. On my 7800 levers with this problem the symptom is that the upshift lever will move but not shift. It can take a couple stabs at the lever to get it to shift. It's worse in the cold.

The levers also have noticable stickiness when you move them. On advice of a shop owner friend who has done this many times I used "CRC Powerlube". Squirt it into the mechanism and let it drip out. Do it a couple times. It sees to have cleared it up. WD40 isn't a lube. Although it would dissolve the grease it would not lubricate the mechanism.

[Oswald]

It was a known problem with that model. You need a replacement part, can't remember which one though...

[eric]

I don't think there are any replacment parts for the shifters.