Groupset for all-road: Ultegra or GRX?

[p nut]

On my allroad, I run about a 1:1 low gearing. It’s been great with no issues on plenty of climbs. I’d go Ultegra.

[weisan]

I like to stretch the limit or go beyond "what the manufacturer recommend". I don't read manuals or compatibility charts. I just go. Sometimes I succeed, sometimes I don't.

Just as an example of what's possible. I built this up a few weeks ago. So far so good.

GRX Di2 2x
Ultegra RD
11-42 rear
52-36 front

[Philster]

I have GRX 11 speed on my all road oriented Crux. I think the question to ask yourself is “how often do I actually use my largest road gear?” For me it’s a 50 - 11, and the answer is “not much “. So the GRX gearing is great.

[Xrslug]

Depending on your riding environment, the other distinction between the two groups is a clutch. If you are riding really rough dirt roads, jeep trails, fire roads, etc. a clutch is nice to prevent your chainstay from getting battered by the chain and reduce chain drops. I know it’s not necessary, and I’ve ridden plenty of mountain bikes and “gravel” bikes, and even road bikes off-road in all kinds of under-biking misadventures, but if I was building a road-ish bike for the widest range of riding possible and I had the option I’d take a clutch. But that’s just the derailleur — you can still mix and match your other pieces. There is one Ultegra 11-speed mechanical derailleur that had a clutch but I’m assuming you’re looking at new / current parts, so it would be GRX.

[RacerJRP]

My "all-road" bike is setup with DA-12, compact up front an 11-34 in the back. Gets the job done everywhere. My "gravel" bike is setup with Ultegra-12, compact up front and the 11-36 105 cassette in the back paired to GRX-RD for range and retention.

That said, to separate the bikes a bit more, I have some 49/33 TA chainrings I'm going to throw on the gravel bike. Just to touch up the ratios with the taller/ fatter rubber and see what some really low gearing feels like. The 49 may have me under-geared for some of the faster gravel courses though.

In short, I vote for the road group, and throw on the GRX RD if you desire. Just note it is a bit chunkier in appearance and weight. That 11-36 cassette isn't light either.

[Turkle]

Originally Posted by RacerJRP

That said, to separate the bikes a bit more, I have some 49/33 TA chainrings I'm going to throw on the gravel bike. Just to touch up the ratios with the taller/ fatter rubber and see what some really low gearing feels like.

This is an underappreciated point. Bigger tires do change your gear ratios, so I think a slightly lower gear is helpful when running 700x42 or whatever.

[Gummee]

My 2 CX race bikes see much more road duty between CX seasons than gravel duty.

They're both S11 mechanical and both have the clutched Ultegra rear derailleur.

I have a few sets of wheels that I'll swap in depending on what I'm doing but the most common wheelset has 32c GP5Ks on it and a X-28c cassette. The others have X-32 or X-34 cassettes in them with 40c tires

If I wander down towards Wintergreen ski resort that x-34t cassette is barely low enough, but for my normal riding here in the cowfields and horse country outside DC, it's too low.

The TL/DR version: get the gearing for the terrain you'll usually ride. More road: Ultegra. More off road: GRX

M

[erolorhun]

YMMV but I find the GRX STI shifters way too bulky. And I have size XL hands. I swapped the entire group on my 3T Exploro to Apex eTap because I just couldn´t get on with the GRXs.

If I would get my Exploro today, I would build it up with levers from Shimano`s road lineup, purely on how much better they sit in the palm of my hand.

[LGrider]

I built up a bike with 12 speed ultegra except for a GRX front derailleur and crank. I like the 48x31 crank for lower gearing while maintaining small steps on the cassette. The front chainrings don't shift as smoothly as a full ultegra setup but it's reliable.

The frame required the wider GRX chainline which also increases the Q factor. If a road chainline would have worked I'd have gotten a Praxis road crank with lower gearing and a road Q factor.