Shiman GRX Dual Control Issue

[Boab]

After completing the Festive 500 I decided to give the bike a bit of TLC. So yesterday I took the wheels off and gave everything a scrub. When I put the wheels back on, the Shimano GRX ST-RX810-R dual control lever wouldn’t shift back up the cassette to an easier gear. It was getting dark, so it went into the shed till this afternoon, when I could get another look at it.

Same thing today, the shifter does nothing. The small lever to go down to a harder gear goes all the way out, but has no resistance, while the shifter to go up the cassette, to an easier gear, doesn’t budge. I took the bar tape off, removed the gear cable, but even with that removed, the shifter wont budge. I made sure the cable outer was seated correctly and that the gear cable was in nice and tight, even over tensioning it at the rear derailleur. No amount of forcing would make the lever budge though.

Anyone come across anything like this before with a Shimano dual control lever? Any ideas what I need to do to get it working again…?

[fatbikephil]

I think you may be the only person on here with GRX.....
I'm contemplating it but it does seem affy complicated.

[Boab]

It's been reliable up to this point. I had a similar issue when I first built the bike, but it just started working and has worked ever since. I'm just struggling to see how removing and then fitting the rear wheel, would stop the shifter from working. I was supposed to be doing 100 miles tomorrow, instead it looks like I'll be off to the LBS.