Hip Pack Shootout: Hydro Flask 5L Down Shift and Thule Rail 4L

Hip packs are still raging strong and have proved their functionality since they debuted years ago. Two of the most recent brands to throw a hip in the game, Hydro Flask and Thule, need no introduction. Thule has been making some great hydration packs for a few years now and released the Rail 0L, 2L, and 4L hip packs in the summer of 2020. Hydro Flask has also done a bang up job on their hydration packs since they launched the first Journey pack in the spring of 2019, and now have the Down Shift 5L for the hip pack crowd.

I received both the Rail 4L and the Downshift 5L around the same time. Both are similar in nature and intent, so we’ll knock out the review for both on the same page. I was also eager to try the Rail 4L after really enjoying the smaller Rail 2L earlier in the year.

Inside out

Before diving into how both packs worked, let’s look at the details a little more closely.

Thule Rail 4L

The Rail 4 uses a 1.5L hydration reservoir, with the hose wrapping around the wearer’s waist and securing via the ReTrakt magnetic strip. There are a few organization pockets in the main compartment which shares space with the reservoir.

The belt has a double retention system and uses Velcro and a traditional snap buckle. On the ends of the belt near the pack are some stretchy sleeves to stuff gels or a set of keys into. On the outside of the Rail 4 is a fleece-lined media sleeve, and another sleeve-like pocket, good for flat things, like tire levers or stroopwaffles.

The Rail 4 weighs 1.35lbs and sells for $100.

Hydro Flask Down Shift 5L

The Down Shift 5L also uses a 1.5L insulated reservoir. Like their hydration packs and the bottles they are famous for, the Hydro Flask reservoir compartment is also insulated, for double the cold water magic. The hose stays put with a single clip on the left hip.

There’s a secondary compartment surrounding the back of the hip pack, with stash spots and a nice organizational theme to it. There are two straps running over the top of the pack for cinching it down to a tighter form.

The Down Shift 5L weighs 1.6lbs and retails for $100 and should be available for sale in March.

On the trail

When fanny packs reach this volume and the weight that comes with a 1.5L full reservoir strapped around the waist, things can get bad. A few pounds of sloshy water weight can be really annoying when it’s bouncing up and down your back on the trail. Both Thule and Hydro Flask have done a good job with the reservoir placement and fit to reduce the motion. The Hydro Flask Down Shift felt a little better though.

I loved the Thule 2L for one- to two-hour rides. It’s slim fit was perfect for the basic necessities and a bottle. The loaded up Rail 4L wasn’t overly bouncy, but it slid downward more than I’d like. I didn’t have this problem with the 2L, but the Rail 4L doesn’t feel quite as secure as the Down Shift 5L with a full reservoir. The offset buckle and strap on the Down Shift and meatier hip straps seem to keep it in place better.

The Rail 4L also doesn’t feel as spacious as the Down Shift 5L. The Hydro Flask pack feels like it has more usable space for cargo, as the extra liter in the title reflects. Jumping from the Rail 2L to the 4L felt more like a different way to hydrate, with a reservoir versus bottles, and a loss in storage space. With the reservoir full, it’s still challenging to fit bulkier items in the main compartment.

The extra pouch on the outside of the Down Shift has more room for bulkier objects like a GoPro, and I also found I could use the top straps for stuffing a rain jacket underneath. There are also bottle pouches on the Down Shift and zippered pockets in the hip straps for keys and small things, whereas the Rail is a little simpler, with stretchy exterior pockets on the hip straps for gels and snacks.

The Rail 4L takes the cake in drinking ease though. The ReTrakt magnetic hose is simple to peel off the hip, drink, and snap back on while pedaling. The Down Shift 5L isn’t as easy with the retention clip.

Both of these hip packs have good breathability. Both hip packs have a good aesthetic, but the Rail is more sleek, the Hydro Flask more pouchy, though this gives it a storage advantage.

Lastly both reservoirs are pretty simple to fill. No tricks here. The Hydro Flask’s insulated reservoir and bladder compartment continue to work well, keeping water nice and cool. All of their packs have done this rather well, and cool water off your back on a hot day is a pretty sweet feature to have.

Closing thoughts

Both the Rail 4L and Down Shift 5L are excellent hip packs for longer rides with a little more gear. If you want something simple, with a clean look that’s easy to hydrate with on the go, and don’t need to pack a lot, the Rail 4L is great. If you need a little bit more room, and need a hip pack to pull duty as an all day option, then the Hydro Flask feels like the better option.

Share This: