Shimano GRX 1x Vs 2x - Which is best for your gravel bike?

One chainring or two, that is a question I get asked loads. So in this video with the help of two Shimano GRX-equipped bikes, I’ve set out to highlight the main pros and cons of each set up to help you choose the best for your riding requirements when shopping for a new gravel and adventure bike in 2021. Range, gaps, weight, simplicity and much more are covered, along with my riding impressions of the overall GRX groupset.

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[mattmacpherson]

Great review thank you. I currently run 3x on my hardtail gravel bike. I am older and less experienced than most. 62 and 1, 000 miles last year. Had not been on a bike for around 40+ years. Cadence feels important to me so I feel the transition to 2x would be easier than 1x. I also have read that the Specialized Diverge with the GRX 810 group set can accommodate up to 47 MM x 700 C. That should be enough tire for my style of riding in Central WI. Long low grades on smooth gravel and a little bit of single track. I can still put on the 2.1” Schwalbe Rocket Ron’s on the MB for winter fun.

[SurpriseMeJT]

Let's take a look at the "disadvantages" of 2x:
Once I setup my front derailleur, I rarely have to play with it so that's not an issue.
More to break? In theory, but I've done XC races in the mud and even if the whole rear cassette is caked in mud, the rear derailleur stops shifting, the front derailleur still works.
I view 2x as also a redundancy measure, not a point of failure.
Tire width? Mountain bikes have had 2x and 3x before... how wide do you need your gravel tires to be? Simply build bikes with longer chain stays (Ritchey Outback for example). The obsession with short chainstays is a bit odd given the need for stability on rough terrain.

[BikeLife]

I can see the benefits of 1x for off road, but for a road bike 2x is the only one I want.

[rossking]

Excellent review, David. Thank you. I have a 2X11, 48/31 - 11/34 Shimano GRX drivetrain on my gravel bike and I love it. And,  I have a 1X12, 32 X 10 - 51 Shimano XT drivetrain on my hardtail mountain bike and I love it, too. With gravel riding it seems that cadence is a really important factor. Similar to road riding. You can see the terrain changing and you have time to consider your exact gearing requirements to you achieve your desired cadence for the upcoming climb or descent. Conversely, with mountain biking it seems there are always lots of immediate decisions to be made .... body position, line choice and selecting the right gear. A simple drivetrain with a good range of options immediately available is paramount. This is where the 1X shines. And the precision and certainly when picking gears fast is a real Shimano strength. I'm really happy Shimano has made these two drive trains available. They both work great for me.

[rogercmerriman]

I’d imagine either would be fine!

A lot would depend on how the bike is being used, some Gravel bikes do seem to be used as XC MTB at which point big tyres and 1x makes sense!

For myself I have a decent trail MTB that is a lovely bike and well is great off road, plus a Gravel bike that I mix up road, and trails for that 2x feels a better fit, especially at 10speed once 12 or 13 can’t really see why you wouldn’t go 1x.

Same goes for tyres I run fairly thin and quick rolling gravel tyres, if the bike can’t handle the terrain it’s probably a hint that I should be using the MTB! Don’t get me wrong sometimes it’s just fun to push the limits!

[richscorer]

Less spendy option of two bikes; DI2 2x GRX, 2 set of wheels (700c / 650b) to sort the tyres clearance! Also I agree the Di2 front mech / gear changing is truly amazing when covered in the UK mud.

[nikveldkamp]

The tire clearance is only influenced by the FD with short chain stays (esp. with narrow roadie Q-factors). Smarter geometries offer much more options. E.g. I choose my wheelsets depending on the terrain from 700c x 32mm up to 700c x 50mm in the rear, even 2.25 in the front. Ultegra drivetrain, 2x11, 46/30 in the front (absoluteBlack chainrings), in the rear 12-26, 11-32 or even 11-42 ( w/ 1.85m spacer). Mega range for variyng terrain, steep ascents and cargo. Different lengths of chains, of course, but everything with the same standard Ultegra2x crankset & RX rear derailleur. Without problems.
My son rides a similar set-up (50/34in front) but it is his frame with shorter chainstays that limits the rear tire to 700c x 47. It's the tire height colliding with seat stay bridge and yoke. He still can go wider, though. So on his 650b wheels he runs 48 to 50mm and still has clearance, maybe even @ReneHerse Umtanum Ridges, 650b x 55🤩

[mancello]

Why choose? Get two bikes. One with 1x the other 2x. Problem solved.👍🚴🚴🚴

[thormusique]

Cheers, mate! This is extremely helpful info. I'll definitely be going with the GRX 2-by, for all the reasons you mention.

[m-]

I have a gravel bike with 1x. I love the look of it and it’s perfect for XC rides.
Defiantly limiting when road riding.
Good excuse really to have
Gravel bike with 1x and a road bike with 2x Di2

[paulbrook]

Makes great sense what you was saying, and I wish I could have a use for any of theses bikes. I think they look great . But the truth is - there’s nowhere to ride these sort of bikes where I live . High peak Derbyshire is either road or mountain bike, the few gravel trails are now to busy with dogs and walkers .

[jameslee-pevenhull]

I have four 1x bikes. The youngest is from 1974. As the guy says, gearing range restrictions is a disadvantage. This, would you believe, is why the double chainset was invented.

[jrs]

GRX 11-34 Cassette- First 6 sprockets 11, 13, 15, 17, 19, 21
GRX 11-42 Cassette- First 6 sprockets 11, 13, 15, 17, 19, 21

So the ‘significantly bigger gaps’ only come in to play when you’re cycling at less than 14mph.

Maybe all the 2x fans like to take it easy when they are riding gravel? ;-)

[JuvoII]

I feel the Ultegra has some ground to conquer here. Namely a 1x Ultegra with 12 gears, really should be able to setup a casette that works for you need. You get the ultralight Ultegra, made even lighter by ditching a front chainring, for the lowest possible weight. Has to be a build.

Alternatively, SRAM has the Eagle series, that also delivers 12 gears. It comes in 3 versions. As you step up in Shimano quality, you get an extra gear. 9-10-11-12 from Sora through Tiagra, to 105 and then Ultegra. But the 3 different quality Eagle gears will all support you with 12 gears. The intro gear made of steel and plastic, the step up aluminum and carbon, and the premium then further refined. Point being, you can make a 1x 12 gear bike with any of these gears to match your desired pricepoint.

[chriskros]

Gears used in gravel bikes are predicted for King Kong or E-bikes.
I had to change cassete from 11/42t to 11/51t that allows me to ride uphil. (40T front)

[MrJwmurph]

I've a SRAM 1X 12 speed on my MTB and I find myself running out of gears on the faster sections or if using it on the road quiet a lot. It's fantastic for simplicity but there are limitations mainly when speeds are higher. I don't find the steps as big an issue as you quickly adjust the cadence to the ideal one after a change. I agree that the riding type should drive the decision, 1X for more off-road & technical and 2X if you want a multipurpose bike than can do it all and with more comfortable road gearing.

[nickw]

cheers well timed as considering buying the reasonably priced boardman ADV9 with a 2x

[matthewclara]

Nothing in there made me think 1x is superior to a 2x. Sure you keep saying the 1x might be lighter and it's definitely simpler because there's only one instead of two, but I have literally been riding bikes with two derailers since I was 12 years old and I am 55 now and I am well aware that two derailers is not a burden. And now I'm looking around for a carbon fiber 2X GRX 600 and I'm having a hard time finding one I want. Most just offer the 1X with 650b. I want 2x with 700c.

[christopherhood]

i think i’ll stick with my ekar, so much nicer to look at, no cap issues.

[fennec]

lets face it Shimano is bullit-proof no matter 1x or 2x and GRX is no exception.

the tire clearance for 2x also depends on your frame geometry - most gravel bikes
take wider tired regardless of 2x - my GRX 800 setup on my bike can take up to 700x47 or 650x53 - that enough to handle some pretty chunky tires !