has anyone tried a gpx chainset with an ultegra front mech and shifter ?

apologies ! i meant GRX. has anyone tried GRX chainset with ultegra front mech and shifters. not supposed to be compatable I know, but maybe?

IIRC the GRX chainrings sit further out from the downtube and so require a GRX mech. Shifters should be fine though.

As always, it’s worth trying. Shimano are notoriously conservative with regards to these things.

Any particular reason you are wanting the GRX chainset? I was putting together a new drivetrain for my #gradventourer and fancied GRX for the lower ratios but bought a 50-34 105 chainset instead (hey, it was available in silver) and it’s running with a 11-40T cassette and a Ultegra rear mech.

thanks scotsroutes, that’s an interesting combination. if you’re riding on the road, are the jumps in gears noticably big? I have one of those chinese carbon frames (cx) with a 50/34, its a very light and well balanced road bike. this autumn I was booked to bikepack tour Montenegro and I figured the slightly easier chainset might help in the mountains

The jump to the 40T is noticeable but I try to avoid that and, when I need it, I don’t care 🙂

Scotroutes – what size rear cage are you using?

I’ve seen a few articles/threads that have said a normal Shimano road front mech just about has enough adjustment to work ok with the 2.5mm wider GRX cranks. I guess it may depend a bit on the seat tube diameter as a wider seat tube would sit a mech slightly wider from the centreline and therefore more likely to be able to cope with the GRX crank offset. As said above, worth a try and if it doesn’t work get a GRX front mech. The other thing worth considering is the ability of the mech to handle the smaller chainrings (46-30 or 48-31 depending on which chainset you are looking at). Again will probably be ok but best to try.

@murdoverthehill GS cage. Called Medium but it’s the longer of the two.

I didn’t need any mech extender, but had to go to a 118 link chain. That’ll obviously depend on your chainstay length too. I get full operation, including cross-chaining.