A Review of the Ventra Gear Mainframe

Having started my hike of the Appalachian Trail in 2014 with 55lb of pack weight, I decided to reduce all I could and make my adventure so much more enjoyable. I was using an Osprey Aether 70 pack and this alone added near 5lb to my base weight. Luckily for me, a trail family member and fellow hiker, Coley, offered to loan me his HMG Windrider Cuben Fiber pack. This was nearer the 28oz mark and helped me reduce my base, with other changes, from 55lb to 20lb. However, one part of using a Windrider is the lack of back ventilation. The Osprey has great ventilation through the spacer mesh which assists airflow and therefore wicks away moisture from your back. The Windrider sits flush against your back and, because it’s Cuben Fiber, the material neither breaths nor wicks moisture away. Pretty soon, even in mild weather, your back is soaked and sweat is seeping down your back into your trousers.

I loved the Windrider and purchased a pack for myself after the hike, having returned the loaner to Coley. I had resolved to the fact that if I wanted a light pack which was waterproof then I had to accept the wet back issue. Until now that is!

I was fortunate to be approached, via Appalachian Trials, to review a new product which was still not on general release: a pack extension or “mainframe,” which can be added to any pack and give the benefits of a breathable space between back and pack.

The idea seems simple and the mainframe does exactly what it says on the tin, maybe because the engineering and development was completed by a mechanical engineer with a passion for Mainframe+025+1+Perspectivehiking. Mike Wright saw a problem to the fact he owned many packs but all of them lacked the breathability he wanted: “So I was stuck sitting there thinking, ‘Well what do I do now; upgrade all these backpacks even though they’re all in pretty good shape?’ The more I thought about it, the engineer in me realized that if the backpack and the breathable suspension were independent entities, it solves a lot of problems.”

And from a problem came a simple solution “The Ventra Gear Mainframe.” Preparing for launch in August 2015, I was given a chance to field test the mainframe several times during the summer. I say summer, as I used the mainframe on a hike in England so was truly tested in adverse weather and conditions. Perfect!


  • The Ventra Gear Mainframe is simple to connect to your current pack; it literally takes seconds. No fiddly buckles or undoing your pack straps; it fits against your pack and attaches using four elastic ties to hold the frame in place. The frame does not actually hold any of the weight of the pack, and although I’m no engineer, I do see this as a benefit. The pack functions just as it was designed to: the mainframe is held between your back and the pack, rather than becoming part of the pack. This means the weight is distributed through use of the pack’s hip belt and shoulder straps and the pack functions exactly the same as if the mainframe was not attached.

  • Weighing a mere 11oz means the mainframe does not add significant weight to the pack system. I was surprised that the frame is so solid; clearly construction for the rigors of outdoor lifestyle has been a consideration.
  • The fit is solid and ergonomic. My first concerned when I saw the mainframe was that it would lead to chafes and sores due to movement and rubbing. But I never encountered one issue in the several times I used the frame. In fact, I completely forgot I was even using it. The fit is comfortable and integrates perfectly with the pack.
  • Breathability is the main reason the frame was developed and it certainly does assist in solving that problem. Mike’s idea came from his passion to reduce fossil fuel use by cycling to work: “I was really tired of arriving for morning meetings with a sweaty back from where my backpack touched.” The mainframe sits against the back by use of a mesh screen which allows the circulation of air and wicking of moisture. On my first outing with the mainframe attached to my pack I noticed cool air across my back while climbing Kinder Scout in England. As I have used the HMG Windrider for over 1000 miles, I had become accustomed to its fit and feel and the heating against my back. This cooling action was a new experience and just like you had been used to something you had used for years it was easy to pick up on the difference.
  • Pack integration was easy. The frame comes in three sizes:

Small= 16-18in (41-46cm)
Medium= 18-20in (46-51cm)
Large= 20-22in (51-56cm)

  • A simple measurement from the base of the pack to the point where the shoulder straps meet the frame gave me my required sizing. There were no issues with the sizing or fit.
  • Flexibility of use means you can add or remove the frame in literally seconds if you needed to. For instance, you may remove it for winter hiking when you may not desire the cooling effect…or if you really did want to save those 11ozs and go ultra-lite.


  • Through my evaluation, I could find no negative aspects to the Ventra Gear Mainframe.

I really like the Ventra Gear Mainframe, it solves the only problem I had with my favorite pack and now makes my system work just as I wanted. It adds minimal weight with ease of fitting and use. One thing I still need to confirm is if it will allow me to add a piece of plastic pipe which will enable me to have a mounting system for my umbrella. Win-win!

The Ventra Gear Mainframe will retail with an MSRP of $75 and details are available on the website www.ventragear.com



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Comments 2

  • C Wilson : Dec 2nd

    The frame sounds perfect and opens up options for packs, such a good thing. Attaching an umbrella stand is brilliant too, please let us know if that works.

  • Chase : Sep 21st

    Why can’t I find this product anywhere online to purchase??


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