Gravel bike gearing: should you run 1x or 2x?

Choosing between a single chainring – known as 1x – and a double chainring – hereby referred to a 2x – isn’t a straightforward choice. You’ll find plenty of proponents of both drive chain options, both online and among your riding buddies. Both camps will insist they know best. But is there really a better option? Well, that depends on a few important considerations.

Whether you opt for 1x or 2x will come down in part to the kind of gravel bike riding you will be doing. Do you live in a city where you need to hit the asphalt first in pursuit of the gritty off-road stuff? Or are you blessed with mile after mile of smooth gravel and fire roads right in your backyard? Perhaps you plan on racing on your gravel bike? How about going on a bikepacking adventure? Do you need your gravel bike to double-up as your winter road bike or as an all-weather commuter? So many questions. So let’s dig a bit deeper into each drive chain option to help you find some answers.

1x – The simple life

You’ll be familiar with the 1x set-up if you’re coming to gravel from a mountain bike background. Most mountain bikers ditched their front derailleur years ago and have never looked back. But if you’re a roadie and this is your first foray into gravel you might be asking why you would knowingly get rid of half your gears? 

The simple answer is just that: simplicity. 

By losing a chainring you also lose other parts from your bike. The front derailleur. The shifting mechanism in the lever. The cable that links them. You’ll shed some weight, with a 1x set-up being on average 200-250 grams lighter than a 2x. And in its place you’ll receive plenty of reassurance, which could be just what you need if you’re riding gravel for the first time. 

So where might this added confidence come from? 

In the case of 1x simple also means reliable. By having fewer parts, in theory means there is less to go wrong. A correctly set-up and maintained modern front derailleur works like a dream. But a knock here, a loss of cable tension there and you’re no longer enjoying the sweet sound of compacted gravel under your tires. You’re listening to the annoying rattle of chain rub instead. A 1x system delivers a super quiet and dependable ride thanks to a couple pieces of technology that have helped its rapid rise to prominence in the gravel scene.

A 1x system utilizes both a specially designed chainring and rear derailleur that in unison help to ensure that the chain stays in place, regardless of how rough the terrain may get. To hold the chain secure, the chainring features a special tooth pattern, generally called narrow-wide in reference to the alternating tooth width. Because the chainring doesn’t have to assist with shifting the chain as it does in a 2x system there is no need for a compromise here. Which means dropped chains will likely be a thing of the past.

The chainring is paired with a clutch derailleur, which in simple terms is a neat built-in device that adds resistance to the derailleur. It’s another slice of tech borrowed from the mountain bike world, which means it’s been tried and tested in the harshest of conditions. Goodbye chain slap. 

Having a single chainring also makes finding the right gear straightforward. For a start you’re only ever using one shifter. When the terrain, or your legs, dictate you simply shift up or down to find the gear you need. No more having to consider whether you need to move from the big chainring to the small and then compensating with a couple more shifts on the cassette. 

2x – a case of what you know?

If you ride a road bike then the 2x system is likely a trusted friend. Continually refined over the years it now works with great efficiency. It’s the preferred choice of grand tour winners and weekend warriors the world over. Having two chainrings provides a significant choice of gear ratios when paired with a 10 or 11-speed cassette. The wide range between the high and the low gear ratios translates to being able to go fast and climb the steep stuff all on the same bike. This option may also suit you if some or a lot of the riding you do on this bike will take place on the tarmac. 

But how about its specific merits on gravel?

While a 1x set-up offers an advantage to newer riders and those used to riding a 1x mountain bike, the familiarity of riding a 2x on the road translates when you head off the beaten path too. Shifting will feel intuitive, allowing you to focus your attention on the gravel ahead. It’s also important to note that both Shimano’s dedicated GRX gravel groupsets and SRAM’s AXS groupsets also offer a clutch rear derailleur on their 2x systems, providing improved chain security that was once the domain of the 1x only. 

Gearing – range and gaps 

The gearing ranges offered by a 1x and 2x set-up may ultimately be the deciding factor in your decision. Gearing ratios can be a little confusing so we’ll keep it simple and deal with the two primary concerns. Range and gaps.

Range simply means the difference between your easiest gear and your hardest gear. So which system offers the widest range? A modern 2x drive chain designed with gravel riding in mind is probably going to win out here. Shimano’s GRX 2x chainset is offered in two options, including a 48/31t combination, providing a huge 17t range on the front. Match this with an 11-speed 11-34t cassette and you have an expansive range that a 1x set-up can’t quite match. SRAM’s AXS groupsets are also designed to offer you the widest possible range – its Force AXS chainset comes in a number of options including a super wide 43/30t option that can be matched with a 10-36t cassette. 

But that’s not to say that a 1x doesn’t still offer an impressive range. A typical set up using a dedicated SRAM 1x groupset will see you riding a 40, 42 or 44t chainring with an 11-speed 10-42t or 11-42t cassette. A comparable set-up is also available with Shimano GRX. The wide range cassette provides a low gear that will get you up the steep stuff while still offering a high gear that will allow you to get plenty of speed up before you spin-out. The recent advent of “mullet” builds (business at the front, party at the back!) which sees 10-50t mountain bike cassettes and rear derailleurs paired with drop-bar road shifters has seen 1x ranges pushed even further. 

Perhaps the biggest difference between the two options is found in the gaps between the gears – also referred to as jumps or steps. Because a 2x has two chainrings it can be run with a closer ratio cassette without sacrificing its overall range. Closer ratios make the jumps between gears smaller. This allows you to easily match the gear with your desired pedalling cadence. This translates to smooth and efficient pedaling, especially on tarmac and compacted gravel surfaces. It’s also helpful if you’re riding in a group and need to maintain a pace that you’re not dictating.

Compare this to a 1x system and you’ll see a significant difference. The wide range cassette means there are larger jumps between gears. You might find this to be less of an issue on gravel – particularly on rough surfaces when you’ll be travelling at slower speeds – but roadies who decide to opt for a 1x will notice the gaps when compared to their road bike.

Your gravel ambitions

So how do these gearing options match with your riding plans? If you’re going to be riding long undulating gravel roads and steep singletrack, you’ll need plenty of range. Both a 1x and 2x deliver this, so it may just come down to preference. But if you’re also planning to race on your gravel bike or use it on a mix of paved and gravel roads then a 2x could be the way to go. 

However, if you’re using your gravel bike as a dedicated off-road machine this could tip the balance in favor of 1x. Add in the desire to undertake a few off-road bikepacking trips into the wilderness where you’ll need to be mechanically self-sufficient and the greater simplicity of a 1x set-up makes a good deal of sense. 

Other considerations

A 1x drive chain allows you to run wider tires. Without a front derailleur to restrict clearances, frames can be designed with relatively short chainstays. This keeps the ride nimble, while still allowing room for tires in the 42-50mm wide range (depending on whether you have 700c or 650b size wheels). Wider tires can be run at lower pressures. This improves traction and provides additional cushioning – just what you need if you’re planning on riding on rocky, undulating roads and trails.

The simplicity of a 1x drive chain also helps create a clean looking bike. If aesthetics matter to you (of course they do, you’re a cyclist!) then this seemingly secondary point could well be worth giving some serious thought to. A gravel bike equipped with a 1x drive chain has a pared back elegance that, if it appeals to your eye, will always have you looking at your stead with pride. 

This content was originally published here.

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