Gregory Goes There

Ventilated backpack suspensions are great, but in our mind, no one has yet come up with a truly ventilated suspension. By that, we mean having nothing at all - no mesh or anything else - sitting against the middle part of your back. That is, until now …

Gregory’s new 2010 JetStream LTS packs just hit the streets this week, and are available on a limited basis for the next month, until they’re more widely available in 2010. That’s the earliest we’ve ever got our new packs for the next season on the market and, yes, it is - for you astute shoppers out there - just in time for the holiday shopping season.

What’s new and notable here is that the seven new packs in the 2010 JetStream LTS series (four Z series packs for men, and three Jade series packs for women) are the first packs to achieve ventilation without using the ubiquitous mesh panel that you’ve found to date on backpacks that offer ventilation across your back.

So why is this important?

Two reasons. First, having nothing at all against your mid-back is more breathable than having a mesh panel against your back. Sure, mesh is breathable, but it still inhibits to some degree the true free flow of air. (In an ideal world, we think a ventilated pack should only contact your back in the lumbar area and near the tops of the shoulders - the two places you must have solid contact to assure good load transfer, and a comfortable carry.)

Second, the same technology that has allowed Gregory’s designers to dispense with the mesh altogether in this series of backpacks means that these new JetStream LTS series packs carry weights of 25 to 30 pounds and greater more effectively (read: more comfortably) than other such ventilated suspension systems.

On what do we base that claim?

Here’s the rundown. Essentially, everything else out there that offers ventilation in a backpack suspension is some sort of variation on what’s called a ‘trampoline’ design. In a trampoline suspension, mesh is stretched across some sort of frame that’s held in tension, be it metal rods, bars or something else. The mesh essentially holds the whole system in slight tension, so that a space is created behind your back that allows a channel for air flow. But if you were to cut the mesh off, the whole system would lose its tension and cease to function properly. Also, of course, the mesh sits against your back. Even though air flows through it, it definitely traps moisture and inhibits air flow to a degree.

To be clear, we are not saying trampoline suspensions are bad. In fact, Gregory uses a trampoline design in its JetStream DTS packs, a smaller series of day packs up to 35 liters. The reason is this: Gregory’s design team thinks they’re great when you’re trying to build a very lightweight, supportive backpack suspension. Why? You can build a much lighter suspension using a trampoline design than you can using a traditional framesheet design, so they’re perfect for use in lightweight day packs, where you want some support in a very light package.

Research by Gregory, however, indicates that at about the 25 to 30 pound mark (about the weight where you exceed 30 to 35 liters in size), trampoline designs will not transfer the load (and thus won’t carry the weight as comfortably) as a more traditional framesheet/stay design.

So what Gregory’s done with JetStream LTS is employ a design that’s based on a more traditional framesheet with a stay, but curve the framesheet so it sits off your back, allowing air to flow through. (It’s a simple idea, more complex in execution in terms of making sure the materials have the right properties to retain the frame’s shape, yet give the system the flexibility required when you’re hiking with a pack.)

Because the curve comes from the internal structure rather than a frame held in tension, there’s no need for a mesh panel at all. Plus, you get the load-transfer benefits of a more traditional framesheet.

Is there a downside? Sure, nothing’s 100 percent. As we already implied, this approach is minimally heavier than using a trampoline design. But Gregory’s design team has always believed that if your pack carries weight more effectively, putting a little more weight in the suspension to achieve that goal will ultimately save you more energy over a full day than having a lighter pack that carries the weight less effectively.

Moreover, Gregory’s R+D team believes it’s a case of the right tool for the right job. Trampoline suspensions work great in day packs, so that’s where we used them. JetStream LTS works better in packs meant for being out for a night, two nights, three nights or longer. And, with this new series, you get the added benefit of true ventilation - no mesh to inhibit air flow.

Plus, we’ve got a whole new color palette that’ll surely grab eyeballs underneath the Christmas tree.

We’re just sayin’ …