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Kelty Trekker 3900 ST

The Trekker 3900 ST has been discontinued. If you're looking for something new, check out the best external frame backpacks for 2022.

photo: Kelty Trekker 3900 ST external frame backpack


Price Historic Range: $109.93-$140.00
Reviewers Paid: $100.00-$160.00


3 reviews
5-star:   0
4-star:   3
3-star:   0
2-star:   0
1-star:   0

External frame pack which is comfortable, durable, and suitable for use on good trails which don't involve scrambling. I have been using this pack for eight years. Mine is the Trekker ST (short torso).


  • Comfortable—carries load well
  • Comfortable—well padded hipbelt and harness
  • Durable throughout; well made
  • Good organization—pockets and compartments
  • Easy to carry a bear canister
  • Carries loads up to 40 lbs with ease
  • Less weight on shoulders than internal frame pack
  • Carries weight high—better for back


  • Not good for scrambling on rough trail
  • Heavy if total load below 20lbs
  • Carries load high, looms behind head
  • Other people think it's "old fashioned"
  1. I am 5'5" and have a short torso. I had trouble finding a pack that was short enough for my back but had enough capacity for multi day hikes.
  2. I have a few issues with my back and every other pack I've used gave me lower back pain and neck pain. I was at the point of thinking I would need an Alpaca or Donkey!! 
  3. The Trekker has a wonderfully solid and well padded waist belt which is able to be positioned and to stay up on the top of the iliac crest rather than too low on the hips. 
  4. The actual packbag on an external frame pack is carried high on the frame. This is a 64l pack, not huge, but because of the positioning of the packbag, it appears large. If you look carefully, you will see that the packbag is actually well clear above the hipbelt, whereas with internal frame packs the rucksack extends right to the level of the bottom of the hipbelt, or even below it, so that the back is sitting in the small of your back or even down onto your buttocks. This gives a very different feel.
  5. It's very adjustable.
  6. I like the pockets, easy to keep everything handy.
  7. I find it easier and less tiring to carry. It doesn't pull back or down on my shoulders like an internal frame pack does (and I've had a few).
  8. It is easy to adjust, and you can attach things to the outside easily. Organization is easy with lots of external and internal pockets and compartments.

The mechanics of an external frame pack are different—the weight is carried high. This is an advantage on good trail (puts the weight closer to your vertical centre of gravity; transfers weight to the hips better; you can stand more upright and there is less backwards drag on your shoulders) but if you need to bend over or use your hands, the pack can throw you off balance. On good trail it is just a matter of getting used to this, and moving carefully. But if you are mountaineering, climbing across logs over creeks, or bush bashing, an internal frame pack which hugs the body down low and is not so wide, will be a better choice!

For people like me, who find that carrying a rucksack or internal frame pack gives them sore backs (once over a certain weight, for me it's 20lbs),  I would recommend that you try out out an external frame pack. The difference is not simply that the frame is on the outside and the styling is "retro" - those are superficial differences. There is a good reason these packs were invented in the first place. After all, it is easy to sew a couple of shoulder straps onto a sack, why go to all that trouble of creating a frame? 

Finally, I want to mention that each year for the past few years on the trail we have seen fewer and fewer external frame packs, and the ones we do see are mostly carried by older, experienced hikers. But this year we met a young guy carrying one, and he was excited to see our Kelty packs. He began excitedly telling us that he had been unable to backpack, due to injury, and had found this old backpack in his girlfriend's garage, and he couldn't believe how comfortable it was! His injury was not bothering him at all and it made the same weight seem lighter.

My prediction - people will "rediscover" the external frame pack and what is old will be new again. It has its uses, for sure. I have carried mine more than 3000 miles, and have just ordered a new hipbelt and new back mesh panel for it. I hope I can carry it another 3000 miles!

PS Trailspace is saying that this pack is Discontinued but I don't believe that is correct, I have been able to find it many places including directly via Kelty.

Source: bought it new
Price Paid: ~$140

I was looking at internal frame packs when an old timer at the local shop talked me into trying a Kelty external frame. Great decision, this pack is wonderful!

Don't be fooled by the 3900 cubic inch size spec; that only includes the pack bag and not the things you can lash to the frame. I usually strap my tent or sleeping bag (or both!) to the frame below the pack bag so there is lots of room inside for other gear. Given that feature, this pack is probably equivalent to a 5,000 L internal frame pack.

The first time you load up the pack and try to swing it over your shoulder you might feel a little unbalanced. The weight is held a little higher and farther away from you back than most internal frame bags. I got used to it pretty fast and now it isn't a problem, but I'm sure it puts off a lot of people.

Fit: The 'ST' is for 'short torso', though I'm a tall male and it fits me better than the regular version. The frame can be shortened or lengthened to fit a large range of torso sizes. The shoulder straps can be mounted in four different positions for wider or narrower shoulders, or mounted at a slant if you have trouble with them rubbing your arm pits. Ask your local store about different waist belt sizes, too - Kelty makes them!

Best feature: This pack is indifferent to loads. The pack fits and carries the same whether I'm hauling 10 pounds or 50 pounds. This is especially nice since my girlfriend has back problems and I often carry half of her load on top of my own.

Worst gripe: Jingly noise. Everything is attached to the frame with pins and split-rings that can jingle and squeak when you walk. It's getting better as time goes by, but I still notice it occasionally.

I admit that I use an internal frame pack for snowshoeing and skiing since having your load held close makes quick movements much easier. But for muti-day hikes in the summer and fall this one fits the bill.

Design: External frame pack
Size: 3900 cu. in.
Number of Pockets: 7
Max. Load Carried: 50 lbs.
Height of Owner: 6'
Price Paid: $160

I have had this pack for around 8 years. The 5 1/2 pound rating may seem heavy by "modern" standards, but I found the assets offset its weight. I find I stay cooler than with an internal frame.

I like how I can handle the frame without putting stress on the fabric. I prefer the multiple pockets versus the unibody design of the internal. I treat the pockets like "rooms"--one is the "kitchen", another is the "bedroom", another the "bath", etc--so I can find things and stow things quickly and efficiently.

Most people would call this a 3-4 day pack. With careful planning and good food choices, I have hiked 8 days comfortably out of this pack. That is when it weighed in at 45 pounds. Most of the time, I really work to keep it at around 32 or so.

One complaint I have heard about this pack is that it is hard to adjust. Like anything, one must find a good starting point to fit him or herself. I have found this pack very adjustable, and have fitted my pack to people of varying heights and weights. The hip belt is padded and comfortable. I can change strap heights. I can adjust the top rail to carry things on top of the top flap. I can adjust the width of shoulder straps.

My friend has the Sierra Crest version of this pack made for REI. She likes hers equally well. But I will let her put on her own review :)

My husband bought an internal frame for himself when we started upgrading equipment. He hated it. We bought him the men's version of this pack, and he is much happier.

I have found that I do not really get anymore hung up in foliage than my daughter who has an internal frame (which she loves).

The only reason I would consider a new pack is to trim weight with the new generation of materials as my body ages. But for now, I will stick with this tried and true design.

Design: external
Size: 3900cc
Number of Pockets: 7
Max. Load Carried: 45 lbs
Height of Owner: 5'4"
Price Paid: $100

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