New Shimano GRX Di2 12-Speed Group (May 2024)

Equipment
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Oops. Fixed.

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MMVs

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Or YKMV.

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Rotor sells a crankset that is designed to work with GRX which crank arm lengths down to 155mm. I am getting one on my bike right now, so should know how well it works soon enough.

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I suspect the lack of 1x at launch is because the rear mech is going to be so similar (if not identical) to the MTB groupsets that they can’t release one without the other.

I’ve noticed the language in launch videos tends to be “no 1x option… yet” so I suspect they all know it’s coming.

I also spoke to a boutique bike brand at a race a few weeks ago who told me their pre-orders were in but they won’t get any GRX di2 til next year. I thought that was really weird since I was pretty sure this launch was coming imminently. But that brand is 1x only so now it makes sense - as long as 1x is still coming eventually.

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I ride my gravel bike for all my long road rides.

46/33 up front and 10/36 in the back. If I wasn’t so fat I could do a 48/35or a 50/47.

On the road if you want more then a 50 front you need to buy a 52 or 54 crank and a different front derailleur. I have thought about going to a 56 front on my road race bike to not have lower cog loss.

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Is the RD compatible with Road levers, RD and Crank?

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It was on 11s and given that the firmware update also hit 9270/8170/7170 today I’d imagine that’s still true this generation. We’ll probably see a lot of cutsom mixed builds depending on preferences for lever style, chainring sizes, etc.

I have a friend that successfully dialled a 105 FD-R7150 front mech out far enough to clear GRX rings and I know that FD is unique in retaining the adjustment screw that disappeared from DA/Ultegra. Pretty sure RX825 kept the screw too, which makes me wonder if that FD will be able to do the reverse and dial inboard enough to accommodate road chainsets. If not (and this will certainly be the case in Shimano’s official compatibility charts), then it will require matching the FD to the chainset family.

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I was thinking the same thing, but the MTB version almost certainly will be fully wireless unless they have something up their sleeve for a MTB frame battery mount

Really shocked to not see 1x at the launch. That seems to be the direction everyone is going on gravel, be it sram or mechanical grx. Theres gatta be a reason, and its certainly coming, just odd to not have this at launch

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Yeah, I think 1x is going to have a totally different battery setup and be truly wireless. I might guess XTR with this new battery released (or at least visible on key athletes’ bikes) before the Olympics, then similar GRX 1x to follow.

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Makes sense. A corollary is that if they don’t have anything to show off for the Olympics, it’ll be a while.

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The ability for everything sram to be compatible is really a cool feature of theirs. Hopefully will be compatible with the semi-wireless current stuff. Don’t see why it couldn’t be? I’m a total shimano fanboy but hate to say it, sram just seems to have their game on point

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couldnt we say the same for road 12s?

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Yeah. We could. Are we any better off with 12s vs 11s

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nope, and i just converted a sram shifter to 12s and all it took was a small rachet the size of 1 cubic centimeter. We could have had it years ago

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We were promised flying cars, and all we got was 2x12 Di2 (with no 1x option).

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Does anybody know if I can swap from 11 speed to 12 speed and reuse the brake hose?

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Still going to require a bleed, but unlike the di2 wires. Hose diameters did not change.

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Yep. Sounds like you’re trying to avoid redoing the internal routing but otherwise replace everything?

You can reuse hoses and securing nuts (inc olives and barbs), though if you’ve got enough length spare then it wouldn’t be a bad idea to snip the ends off and add fresh hardware. But I guess if you’re going to that trouble you’d be just as well pulling fresh hoses while you’re at it so that’s probably off the table here.

Best plan of attack is to start by draining the brake systems as though you’re doing a fluid refresh (so attaching a hose and disposal container to the bleed port on the caliper, opening it up, then removing the bleed screw at the lever and draining all the fluid out by elevating the appropriate end of the bike, pumping brake levers, etc.). Then you know you’ve got the hoses nice and clean before you start disassembling.

After that you can just undo the nuts at each end, and as long as the hardware is all in good condition then just clean it all up as best you can and add the appropriate grease to the nut threads (I think silicone grease maybe?) and you can fasten in to the new shifter/caliper. Follow shimano dealer manual for setup (fill system from caliper end, then bleed from each end in the prescribed order).

I made sure to clean my old calipers really well, lubricate the pistons, and press them all the way back into the calipers before removing, just so they’d be in good shape to get re-used somewhere else. Not strictly necessary but good practice if you plan to repurpose or sell on. (I wasn’t re-using my hoses but still did the same process of draining the system as described above).

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