Hi anyone using a grx double chainset with a 5800 front mech successfully?

Or what is the smallest inner chainring I can get for a ultegra r8000 compact chainset?

Thanks

We’ve got two bikes with grx doubles here, one 5800 front mech and one r7000. They both work, but not optimally – they are a bit stiff to shift into the big chainring, but fine otherwise. Both running rs685 shifters.

I have a 5800 front mech (with the weirdly long arm) and it works with my grx 810 chainset. Initially I was hesitant because of the 2.5mm chain line difference, but it was fine. It’s heavy to shift, by 5800 always was compared to newer shimano.

I’ve gone Ultegra R8000 with Absolute Black chainrings with an older generation Ultegra front mech (with the weirdly long arm 😎).

Haven’t tested it yet but can confirm you can go as low as a 30 tooth if you don’t mind going oval and paying Absolute Black prices… 🙄

I tried GRX chainset + 105 front der and couldn’t get it to work. Not enough throw. I bought a GRX front der in the end.

It can be made to just about work but the fine indexing goes to pot.

The new GRX front mechs are lovely things, well worth just upgrading. Go 10 speed front mech and crank to save money (assuming you have an 11 speed set up)