Shimano GRX… a long time coming but finally something to get excited about…2/3 tiers of spec. 1x and 2x and even 10 speed options.
The downside being a lack of availability and according to official sources, little or no cross compatibility with existing road Shimano groupsets.
So, I’m currently running 2x11 105 on my CX/gravel bike, and there are a lot of owners out there running a similar set up.
We all know that you can usually get away a with 32T cassette and mid cage 105, even 34T (and possibly 36T on a really good day with an extra long B screw), but the limiting factor has always been that pesky 110bcd chainring and its 34T inner chainring limit.
Well, I’m not prepared to wait for the 11 speed chain set availability or pay a hefty premium, so gambled on the GRX FC-600 10 speed front chain ring in 46/30. I wasn’t prepared to buy a new front mech either just because of a 2.5mm chain line variation…
And as expected it works! Shifting is smooth and the chain runs freely with no rubbing of the front mech in any gear combination
As I mentioned above, the chainrings sit 2.5mm further out to accommodate wider tyres, which does make for even worse big/big cross chaining.
And finally, if you are thinking of fitting an aftermarket power meter, the left hand crank is scalloped on the inside which may well cause issues.
But any 105 upwards HT 2 crank will fit, I simply put my 105 crank with PM back on and everything is now working perfectly.
It’s always a pain to upgrade perfectly good components and whilst YMMV it seems like at least some components of Shimano GRX are good for mix and match.