Unless you're into the fat bike scene, you might not have heard of Wren before this, or maybe you spotted a similar fork being sold under a few different names. All that's changed from 2018 on, though, with Wren becoming the sole name behind the fork and implementing some big changes. I've walked by their booth at different shows for a few years now, but it turns out that I chose the right time to stop in and learn about their revised inverted fork that can fit any common wheel and tire combo and is available with 80 to 150mm of travel. Depending on the travel you want, expect to pay $899.99 to $949.99 USD.
Wren Inverted Fork
Intended use: trail / all-mountain / enduro
Travel: 110mm (80, 80, 100mm) / 150mm (120, 130, 140mm)
Wheel size: 26″ to 29″
Spring: TwinAir system
Damper: sealed, servicable cartridge w/ bladder
Brass keyway system
Carbon fiber leg gaurds
Adjustments: low-speed rebound, low-speed compression w/ lockout
Price: $899.99 - $949.99 USD
More info: www.wrensports.com
The benefits of inverted forks are well-known; the bits that slide up and down are light so that it can respond to bumps quicker, they point the seals downward, and they can be much more rigid front-to-back. You know where they're not as rigid as a traditional fork? Side-to-side, unfortunately, with torsional flex being the sticking point for many people.
Wren isn't the first to employ a brass keyway system to add more rigidity - X-Fusion did it with their Revel, but it never worked well - but they do say that their design has proven to be reliable and trouble-free.
The Wren can be had with 80 - 150mm of travel, and it uses a brass keyway system to add torsional rigidity.
The fork's tubes are broached so that there are two keyways in each one, in which a set of brass keys hold the stanchions from rotating in the upper legs. Why brass? Because it's softer than the aluminum used for the upper tubes and stanchions, and it's an idea that's long been used in dropper posts and many other non-bike things.
We'll have to try it before giving it the nod or the shake, but it's certainly the biggest update for Wren's fork.
Look familiar? Wren's sealed damper uses a bladder to compensate for oil displacement, just like many other forks on the market.
You'll find a damper that looks a lot like a Charger unit from the outside, with a bladder up top to compensate for oil displacement and to provide back-pressure, along with a low-speed compression dial at the top of the leg that doubles as a firm lockout when you completely close it. Rebound is done at the bottom of the same leg. The bladder itself is molded and joined rather than being a seamless extruded piece as found on forks from Fox and RockShox, but Wren says that their approach saves a good chunk of money. The damper is user-serviceable, although some knowledge and skill are required, and Wren also sells every single part for the fork. Need two new shims and a piston bolt? No problem. Need a damper rod or seals? Of course.
You can also pick up a completely new damper for a reasonable $68 USD, or a special cold-weather damper filled with different oil that excels when it's 20°F or colder.
Spring duties are looked after by Wren's TwinAir system that's essentially a single air chamber that's split in two by a floating piston. There are two positive air chambers and two air valves - one at the top and another at the bottom - that are used to control the fork's progression.
So, if you put more air in the bottom chamber, it pushes the piston up and shrinks the volume of the top chamber, which in turn makes the fork ramp up in the same way that adding volume-reducing tokes would. The pressure on both sides will equalize, of course, but the volume of the chambers will change.
The Wren will ship with these bolt-on carbon gaurds, too.
The most interesting thing about Wren's fork is that you can order it in any configuration you require; Boost or non-Boost spacing, tapered or straight steerer, with 150mm that can go down to 120mm in 10mm increments, or with 110mm that can be dropped down to 80mm in 10mm jumps. It fits 26'', 27.5'', and 29'' wheels, up to 2.5″ tires with non-Boost spacing, and up to 3.0'' tires with Boost spacing. There's also a wider version if you want to use it on a fat bike. Weights range from a claimed 4.5lb for the Boost fork with 110mm of travel to 4.9lb for the non-Boost 150mm version.