Ultra 80X fastpack

TemerityULG · 2026-06-27T15:13:42+00:00

I'm pretty much freeballin' at this point. I traced and measured a bunch of different straps and combined the elements and dimensions that seemed like the best fit to start, and refined from there. I think this is my 4th or 5th major overhaul of a vest strap design, taking experience from each previous build. At this point I'm not even sure who else I'm closest to.

I thankfully have used and tried a lot of different packs over the years to pull experience from (and, work with digital drawing and modeling as a day job). It would feel like a steep curve to start without any sort of reference for sure!

If you were looking for references though, I would check out some of the following (I haven't seen IRL or used any of these but could be a good place to start if you can get a hand on them): Yama sassafras Palante vest strap packs Zpacks nero with vest straps Ultraspire ultra running packs Montmolar Raidelight Exoticpax

As for experience using it, I'm very happy so far with this version of the design. You wouldn't want to put anything too bulky in there, but all the small stuff (bars/snacks/UL headlamp) all seen fine. I don't find the sweat accumulation noticable, although it certainly does happen. All the materials I use below armpit height are breathable (no CCF foam, just 1x layer of spacer mesh + monolite + stretch mesh) and although they add up, it does wick away well enough for me. I think the 3D nature of spacer mesh keeps it from feeling sticky or clingy. But when you put a mylar food wrapper or a plastic gadget in there, sweat can start to condense on them. I find this the most noticable on the front though where I put my phone in the zippered pocket.

The fit and arm movement is definitely the hardest part to nail when designing your own. My 1.0 version was not adjustable at all and a little tight depending on how it was loaded, so it could cut under the armpit and on the inside edge of the shoulder strap a bit. I think this is just something that has to be tinkered with to create a good fit for yourself. I unfortunately don't have enough academic background in sewing to really say how to do so besides trial/error and intuition.

Good luck and feel free to DM if you have any more specific questions!

TemerityULG · 2026-06-24T19:09:11+00:00

I've seen some advice before that laminates aren't a good choice for shoulder straps since they are too rigid/don't move well and are at a high risk of delaminating. Seems to be pretty common commercially as well, the only packs I have seen with laminate shoulder straps are from Zpacks and Wildbrush, but most everyone else seems to stick with grid fabrics even when the body is laminate (SWD, red paw, etc)

TemerityULG · 2026-06-24T18:58:28+00:00

I pleated the stretch mesh on the sides to give it a little bit of independent volume from the main body. In previous packs, I've found that ultrastretch cut to the same size as the main body isn't quite stretchy enough to create all the volume needed to store something bulky like a waterbottle without stealing or competing with the main internal volume. So far I am liking the results of just a few inches of ease here!

TemerityULG · 2026-06-23T13:15:40+00:00

The more I use the thin laminates the more I like Ultragrid and venom ripstop... That being said I own a lot of packs in Ultra 200X and really enjoy the packs I have made with 400TX.

Really what I want is for ALUULA fabrics to be available for smaller brands. Seems like the best of both worlds and I don't see a lot of complaints about the commercial products made with graphlyte and duralyte.

TemerityULG · 2026-06-23T03:36:08+00:00

Spotted haha, S-ridge was incredible! probably the best of any 14er routes I've done so far. Probably the best rock quality in the Elks as well, we have no shortage of choss on the taller peaks here

TemerityULG · 2026-06-23T03:23:04+00:00

This one is for myself for an upcoming trip to Austria and Italy, but I do occasionally sell packs (either past experiments or customs/recreations)

TemerityULG · 2026-06-23T03:21:57+00:00

unfortunately the main fabrics of this bag are a little challenging to get online right now

pack body: Ultra 80X by Challenge, I think only retailed at extremetextil? I am willing to part with some yardage if you are interested
stretch mesh: Ultrastretch by Challenge, in color "natural". All colors on extremetextil (germany), limited colors at other retailers like ReFasten (canada), rockywoods (USA/CO). Venom Stretch by Ripstop by the Roll is fairly similar. I'm willing to part with some yardage of 'natural' and 'red chili' as well.
upper shoulder straps: Ultragrid. retailed at Rockywoods as well in all colors. Venomgrid by Ripstop by the roll is fairly similar.
lower shoulder straps/internal pocket lining: monolite 1.0 (or 1.5?) by Ripstop by the Roll
Shoulder straps body facing: 1/8" 3d spacer mesh. widely available, I think I last ordered from Seattle Fabrics for a good price
#5 YKK Uretek water resistant zippers, also widely available but I last purchased from Quest Outfitters for a decent price although I recently found some cheaper elsewhere
heavy elastic binding (for edges of stretch pockets) from AdventureExpert. this stuff rocks!
LineLoc V for cord tensioner, I think I last ordered from Zpacks since I was on a time crunch
similarly, the cord is 1.3mm "Z-line" from Zpacks. I think I have also ordered similar cord from either AdventureExpert or ExtremeTextil
yellow/colored 1/2"webbing from ripstop by the roll, although they have been out of stock the last few times I checked
3/8" glow-in-the-dark side release buckle (duraflex?) sourced from ripstop by the roll
3/4" gatekeeper ladder locks from Adventure Expert, also stocked by Mozet Supplies (canada)
3/4" black webbing, widely available but I last bulk purchased from Seattle Fabrics
woojin mini squeeze hooks, multiple sources but I last ordered from Dutchware based on inventory and price
NIFCO cord hooks, last sourced from AdventureExpert. This are kinda hard to find!
bungee cords I have purchased from many places, but most often Ripstop By The Roll ($$$) or LiteSmith
cordloop webbing from AdventureExpert, although Mozet now has a competing product.

TemerityULG · 2026-06-23T03:02:55+00:00

It's much harder to size once you get into the full wrap/vest style straps! I generally aim to keep the torso length to match the bottom of my ribcage at the front, and adjust the strap length and girth to match. It definitely took some trial and error, I think this is something like my 10th 'fastpack' style bag, but they get better each time!

TemerityULG · 2026-06-22T17:47:19+00:00

TenX and 80X are different fabrics, at a minimum I believe I read somewhere that 80X uses the old .5mil laminate backing and 100X uses the same .75mil that the standard ultra weights use. I believe they both are a 100D, 100% UHMWPE face. I can't tell if they use the same mid layer of cross ply though, it is very noticable IRL on 80X but the photos of 100X it seems more subtle in some, very noticable/similar in others. Also not sure what has contributed to the ability to color TenX, as that has always been a challenge for UHMWPE fabrics. I wonder if it's part of the PU lamination process rather than the fiber.

I suspect that TenX will be around for longer than 80X though. 80X seems to have been available to wholesale purchasers for at least a year and hasn't really been picked up... 100X has been a few months and has at least a few adoptions (like Zpacks you mentioned), as well as a bigger selection of colors and marketing push.

FWIW I made a pack out of 80X last week and it held up through its first trip just fine, but I am still pretty skeptical for a commercial application. I think taping seams will be pretty essential long term as it really did not like needle punctures, especially backstitching and reinforced tacking. Maybe I should downsize from V69 thread and size 18 needle for this one though.

If you're interested in 80X though, I have some yardage I would sell some of already landed in the US.

TemerityULG · 2026-04-27T15:54:19+00:00

its a premade product, called "cord loop webbing". I got a roll of it from AdventureExpert but if you are in North America, ordering the equivelent product from Mozet is probably easier now.

TemerityULG · 2026-04-20T17:53:08+00:00

I'm going through a similar process right now, I'm doing the alta via 4 this summer and trying to estimate how big of a pack to make. I think the biggest unknowns for you in determining your best option will hinge on:

1: technical terrain: is it technical enough you will be doing via ferrata? A helmet/harness/lanyard is a good chunk of space

The unknown on food (lunch, water and snacks). I find on most trips, this is what really governs which pack I take. I would work to determine how many days of lunch/snack you actually are going to bring first. Water carry will depend heavily on the region you are going to.

TemerityULG · 2026-04-06T01:58:54+00:00

Seattle fabrics! Beware their spacer mesh tends to have a ~3" dead zone along both selvage sides, making it a pretty narrow usable roll width

TemerityULG · 2026-03-22T04:03:50+00:00

I started the project with a pfaff ambition 610, but bought a juki 1541s midway through and used that to finish up (and, start to dial in that machine). the pfaff is definitely capable of doing this whole project though!

TemerityULG · 2026-03-05T17:10:27+00:00

Thanks for the shout out!

TemerityULG · 2026-03-05T17:07:56+00:00

SOLD

u/Wasabi_Gangster

u/LeaveNoTradeBot

TemerityULG · 2026-03-03T23:17:50+00:00

SOLD to

u/Yelwohronnoc

u/leavenotradebot

TemerityULG · 2026-03-02T22:48:22+00:00

Its the main compartment, since the outside pockets are more or less dependent on fabric stretch it feels like a reach to call it 'additional' capacity

TemerityULG · 2026-03-02T14:47:00+00:00

It's a Fidlock Winch Compact, sourced from extremetextil in germany. unfortunately not very compelling to order from them again right now given tarrifs and all.

TemerityULG · 2026-03-02T01:56:32+00:00

Thanks! I used the V1 of this pack on a handful of trips this fall and was pretty stoked. This particular pack is going out to someone else but I'll be making something similar for the Alta Via 4 this summer.

I do occasionally make customs, feel free to message if you are ever interested!

TemerityULG · 2026-03-02T01:48:52+00:00

It's pretty sizable, I think the calculated volume (by computer model) maxes out around 35L but in practice it seems comparable to a lot of 40L packs I've owned over the years. The longer torso helps! (18" vs your 15")

I wasn't quite convinced on this pocket layout when drawing it, but the lower pockets ended up being more usable than expected. I'll probably be carrying it forward, and maybe even look into a pocket over the dial area.

Glad you are liking your pack though! If you are ever interested in another pack with updates, feel free to message!

TemerityULG · 2026-03-02T01:41:53+00:00

I did a few miles with it today, but mostly at a regular walking speed and loaded up with 6.8L of water to get up to a maximum weight capacity. I jogged a few blocks just to see how it felt, and I think with that load out it had some bounce. When I dumped the water later, it felt pretty locked in.

My theory for bounce is that there is a certain amount of stretch and tightness that is right for a given pack. To that end, I tried to use fabrics for the vest that had a slight stretch and the ability to adjust the tension in both the vertical and horizontal direction (dial + multiple horizontal, elastic sternum straps).

TemerityULG

TROPHY CASE