After testing out the Co-op Cycles ADV 2.2 gravel bike, I feel confident that the brand did well again with the ADV 3.1. The ADV 3.1 is a steel frame gravel bike, with loads of mounts for bikepacking, bar-end shifters, and a throwback look.

Steel Frame and Fork

Many experienced gravel riders have a soft spot in their heart for steel frames, because they make a lot of sense for a gravel bike. Not only are steel frames strong, but they are inherently very good at dampening vibrations that would otherwise travel through an aluminum frame.

In fact, I prefer steel framed bikes for gravel, and I regularly take my Priority Brilliant L-Train, a steel framed commuter bike that I’m in the process of turning into a gravel bike, on local gravel trails. There’s something very satisfying about riding gravel on a steel bike. It’s like you’re almost floating on top of the gravel, and thanks to the weight of a steel bike, they’re good at plowing their way through looser gravel, while lighter bikes can be jostled around.

This fall, I’ll be taking my L-Train on some rail trails and towpaths, which it should be well-suited for.

So, while you do lose some efficiency and speed due to the increased weight of a steel frame, they have their uses, and gravel riding is definitely one of them. To me, the fact that the ADV 3.1 has a steel frame is a big plus.

650b Wheel Size

The ADV 3.1 is equipped with 650b wheels, and many gravel bike enthusiasts prefer 650b wheels over the more standard 700 c road tire. 700 c wheels are 622 mm in diameter, while 650b wheels are 584 mm in diameter. While some of this size difference is made up in the larger volume size of a 650b tire, they still put the rider a little lower to the ground for increased stability. Running on tires with greater air volume also means a more comfortable ride, and reducing pressure will make the tires more grippy on looser soils.

650b wheel size isn’t going to result in lightning fast speeds on pavement, but they make up for it by offering a more comfortable and sure-footed ride when off-road.

If you’re going to be riding primarily off-road, or on gravel then 650b makes a lot of sense. If you’re going to be riding mostly on pavement and occasionally off-road, then 700 c would probably suit you better.

Bar End Shifters

The ADV 3.1 differs from the ADV 2.2 in that it has bar-end shifters, and there are some advantages to bar-end shifters.

Bar-end shifters allow the rider to quickly change gears without moving their hands from the lowest position of the bike’s dropbar. Being able to keep your hands on the lowest position also means they are at the widest position of the bar, since the gravel bike handlebars are flared outwards at their lowest point. This provides the greatest stability.

A downside to bar-end shifters is that you have to move your hands to use the brakes. The ADV 2.2, in contrast, uses the more common shifters that are located at the brake levers.

Personally, I prefer them at the brake levers, but in some riding conditions, bar-end shifters make a lot of sense, such as on more technical trails where you want to keep up your speed and momentum by staying in the lowest riding position.



Plenty of Mounts for Racks & Water Bottles

One area that the ADV 2.2 falls a little flat are the limited number of mounting points on its frame and fork. While there are two water bottle mounts, and mounts for a rear rack, there are none on the front fork. That was my only gripe of the bike.

REI ADV 2.2 Gravel Bike
REI ADV 2.2 Gravel Bike

The ADV 3.1 has plenty of mounts, including three water bottle mounts on the frame, a top bar mount, three mounting points on the fork, and rear braze-ons for racks and/or fenders. It’s ready for bikepacking adventures that require bringing along a lot of gear.


The drivetrain of the ADV 3.1 offers a double chainring up front and 11 cogs in the cassette, offering a total of 22 gears to choose from. With an 11-42 tooth cassette, the drivetrain has a wide range for both higher and lower gears, making it a good hill-climber.

The ADV 3.1 is equipped with the Shimano Deore Shadow Plus rear derailleur, which has an on/off switch to adjust spring tension for the chain. The clutch helps prevent the chain from coming off the chainring or slapping against the chainstay.


The WTB 27.5 x 50 mm wide tires are designed to handle off-roading well. They’re fairly knobby, making it most ideal for off-road. The rims are also tubeless ready.

Other Features

Other features of the ADV 3.1 are hydraulic brakes, and a high payload capacity of 300 lbs. Cabling is external, so maintenance and future upgrades will be easier to perform.


The Co-op Cycles ADV 3.1, where ADV stands for adventure, is one of the more affordable steel framed gravel bikes on the market today.

The ADV 3.1 is truly built for adventure, with components and features that can handle off-road trails. It’s a great choice as your first gravel bike, especially if you plan to ride on dirt trails, gravel, and even some single-track.

If you’re still shopping around for a steel gravel bike, some other great ones to bikes to consider are the 4130 steel gravel bike from State Bicycles, the Surly Preamble or the Poseidon Redwood as comparisons. These are all highly regarded steel gravel bikes at affordable prices.

If you think you’d prefer a lighter weight gravel bike to handle pavement better, yet still provide good comfort and performance off-road, check out the ADV 2.2. I even had a blast on it on some single track trails. It handled them fine. I also enjoyed using the shifters of the ADV 2.2. The drivetrain was also flawless and handled the hills well. I sure miss that bike.

To learn more about the ADV 3.1 or the ADV 2.2 you can check them out online or possibly in person at your local REI. REI members also get 10% back on the purchase of the bike, and REI offers assembly, 1-year of free adjustments, free flat tire repairs (labor only), and other perks.

This article contains affiliate links, which help support the site. Thank you!

Categorized in:

Bike of the Week,

Last Update: August 19, 2023