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AC Tech Talks - 1x vs 2x

by Derek Yarra |  | 

ac tech talks 1x vs 2x


To front derailleur or not to front derailleur? That is the question. When we work with clients on a new bike build, especially of the gravel sort, one of the toughest decisions is whether to go single or double chainring. Especially in this modern age of cycling with new gearing options popping up left and right, the decision can be a bit of a tough one. Do we still need front derailleurs? Today we’ll cover our personal opinions and experiences to help you decide when you might or might not want to slim down to a single chainring.

 1x 2x header

How long have you been experimenting with 1x systems?


Derek: Maybe about ten years ago I had a 1x set up for a cyclocross race bike. I mostly tried it out because unless you could get your hands on the team only Dura-Ace chainrings, CX specific rings (46/36) were pretty crappy and never shifted that well, especially once a mechanical front derailleur started packing with mud. To keep from dropping chains, it was worth it to have a solid chain guide and a chainring without shift ramps. Ha, I remember a wide range cassette then was a 12-28.

Eventually Sram really opened up the 1x world with the first CX1 group, with a clutch derailleur that could take a 11-36 cassette, and a narrow/wide chainring. That was a huge step in having a high performing drivetrain for drop bar bikes that could handle rougher terrain. I don’t think I’ve ever felt a need to use a chain guide since then.

force 1

Chad: Same as you Derek.  Though it was more like 30 years ago.  We used the inner ring on a 2X crank and then ground the teeth off of the outer ring to make a chain guard on our cross bikes.  Back then it was really the only good choice as drive train components were not so great and when bouncing all around, especially in the Northwest muck, dropping the chain off the rings in front was not a matter of if, but when.


So what’s the deal with this big shift to single chainrings, why are they so prominent now?


Derek: Originally it was limited low end gear range and chain retention for off road riding. Until fairly recently, it was really hard to come across a high quality 2x set up that could accommodate a 1x1 or sub 1x1 climbing gear. 

 why 1x

Chad: For the purpose of this conversation I’m talking mainly about adventure/gravel bikes.  For road bikes I don’t thing 1X is prominent at all and I think that is still a ways off as some other form of drivetrain technology will need to be developed for that to be mainstream.  Unless you ride in an area with little undulation of course, or don’t need to maximize efficiency on the hills, flats and descents.  With that being said, I think 1X is prominent due to the fact that a well set up single ring drivetrain nearly eliminates the dropped chain.

So is 2x still a viable option?


Derek: Yes. Especially in recent years as Shimano has had their Ultegra RX and GRX derailleurs that have clutches and expanded gear capacity. 

Chad:  Absolutely.  The 2X setup is still optimal for cyclists that want to have better access to the optimal gear for the conditions and terrain.  It’s just a bit less reliable in really bad conditions.  For a lot of people, having that perfect cadence on their rides is not the biggest concern.

2x gravel drivetrain


Are there any drawbacks to going 1x?


Derek: When selecting a cassette, you’re basically choosing between tight jumps or ample range. Usually, a rider going 1x is going for range, so the compromise is big jumps, which can also mean clunkier shifts. You’re also usually giving up top end gearing. If you come from a road background, you’ll probably notice this right away, but as a mountain biker, I’ve been pretty used to this for some time. As mentioned before, there’s also something to be said for the big gear change that a chainring shift can provide. 

Chad:  Same as you said here Derek.  But that is why I have a road bike, if I had only one bike and planned to ride a lot off road I think I’d still do the 1X.  Also, and this is not true for everyone, but the 1X is not as aesthetically pleasing with a small chainring and huge cassette.  

cassette range



What factors would lead you to pick 1x?

Derek: Well for one, whether or not your frame can take a front derailleur. My Open WIDE is specifically designed for 1x, but I would have chosen it anyway. I’d say that if the bike is really going to be a dedicated off road bike, then 1x is the way to go. Less moving parts, better chain retention, and no tire clearance issues with a front derailleur. Also, if you’re planning to use a dropper post, 1x is a great way to free up a shifter to actuate that. To simplify things, if you plan to run high volume 650b tires or 700x40c or larger tires, you’re probably going to want a 1x.

Chad:  Sorry, to sound like a broken record here, but again, same answer as Derek gave here.  I have a Bastion Crossroad on order and it is built exclusively for 1X so I don’t even need to think about it.  

choosing 1x



And what about 2x?

Derek: If you’re planning to use the  bike 50/50 road vs dirt, then a 2x might be the right answer. I find on the road it’s much more critical to find the perfect gear, so I really like the tighter jumps.  If you’re mostly riding smoother groomed gravel roads, you might not need a heavier duty clutch mechanism and be totally fine with a 2x system. 

Chad:  If I were racing and the off road portion of course I was racing on was not too crazy bumpy or if the ground was not pure thick mud, I think I’d prefer a 2X.  I’d also most likely be using narrower tires if this were the case so that would not be a factor.  When you are on the limit, sometimes that big jump between cogs can really throw you off your rhythm.  In a race, that sucks.  Out on a ride on your own, not that big of a deal.

2x race scenario



This discussion has been pretty dirt-centric, but would you ever advise on 1x for a road bike?


Derek: Sure. If you live somewhere relatively flat, then it can be a great option to simplify your set up and make things a bit lighter. With something like Sram's 10-42 cassette with a 42 or 44 ring, you'd even get by somewhere hilly. That said, for most road applications I think the value of tighter gear jumps is much higher, and chain retention/front shifting doesn't really prove to be as much of an issue while in tarmac. 

Chad:  For sure!  But it really depends on where you are riding and I guess also how strong you are.  I think road bikes built as 1X are super clean looking.  For where I ride though, it would be a slog going up the hills with this setup.  But, I’m sure I’ll try it at some point in the future.

1x road drivetrain



Does one system or the other better suit your preferences?


Derek: The best way to answer this is to share an anecdotal story of how I came to my current bike stable. Last year my gravel bike was my Mosaic GT-1 all road. It fits a max tire of about 700x38c, and I had built it up with Sram AXS 2x thinking it’d be the way to go for a “race” bike. For some races it was perfect, but for the majority of the riding I was doing, I was basically treating it as a rigid MTB, seeking out the gnarlier trials. It was (and still is) an amazing bike, but for the riding I was doing, I felt like I always needed more. 

So in January this year, I built up an Open WIDE with GRX 1x (11-46t cassette) and ride it with 42-45c tires. It has been such a perfect set up for rides that would be questionably better suited for a MTB. I’ve since set up my Mosaic with aero wheels and 32c slick tires and have truly found an all new love for that bike. It’s the most fun road bike I’ve had, while still able handle most gravel riding. Just gotta keep your speed and line choice in check. One is a Shimano 1x, one is Sram 2x, and both are the perfect set up. 

1x vs 2x derek

Chad:  Just have more than one bike and you don’t need to worry about it! :-)  For me though, when I start speccing out my Bastion that should be here in about 2 months, I’m building this with the thought of it being off road first, on road second.  So I’ll build it to tackle the hills and descents of our fire-roads and trails and am not going to worry about how it does on the roads too much.  That means a 1X drivetrain.  Most likely the SRAM Red AXS Mullet group.  I actually never really thought that I’d need a 50t cog, but I use it a lot.  Also, the 42X10 is not so bad on the flats and descents, so it works well enough on the road.  

For a road bike, 2X works best for how I ride right now.

1x vs 2x chad

Once again, we've concluded that there's no single right answer, and it all comes down to your particular preference and use case. But now that you've heard from us, we want to hear from you. Do you 1x? Do you still 2x? Let us know in the comments so we can keep the conversation going!