18l & 24l FastPacks - lessons learned from 25+ packs so far @montmolar

Montmolar

Trekker
Hey folks,
since I've been pretty known for my FastPack design(s) I want to use this thread to share my learnings and the current state of my design philosophy with you.


The FastPack Origin

My MYOG journey basically started with my wish to modify the existing Aonijie 18l trail running vest (±325g) to better fit my needs and especially use lighter and more advanced fabrics to do so. And as we all know: One thing leads to another and the perfect pack is always n+1.

So since then I have continually evolved the design over the last two years and reached a point where I supposedly have "seen" it all. Which just means: I literally have experimented with so many fabrics, components, tapes and cords, that I pretty much bought every feasible item from any commercial store all over the globe.

I found many gems and so this thread aims to distill the experience into a usable blueprint for each and everyone aiming to make their own Montmolar style FastPack - or any similar pack for that matter!

What you need (and don't)

After much trial and error I can share my findings in terms of fabrics and components as part of the bag:

1) Main pack Fabrics:
  • 40D TPU Nylon (70g/m² or 2oz/yd²) - $ cheap, easy and still quite robust/waterproof. Can be seamsealed / welded. There are more potent fabrics for the weight though.
  • XPac LiteSkin LS07 (115g/m² or 3.4oz/yd²) - $, really nice fabric for its weight, seems durable, great feel and texture. Fully waterproof but hard to seamseal. Maybe problems with delamination on areas of continous folding? (No personal experience so far.)
  • CT5K.18/blkwov4 Hybrid DCF (102g/m² or 3oz/yd²) - $$, nice to work with, fully waterproof, pretty robust, easy to seam tape, quite sturdy, the face fabric will help only so far with abrasion... (seen some wear on my personal EDC wallet).
  • X-Pac X21 RC (150g/m² or 4.4oz/yd²) - $, rather stiff and burly, holds stitches well, fully waterproof, can be seamsealed, I don't miss the inner fabric vs. VX21, problems with abrasion on x-pattern?
  • CT5K.18 1.43oz DCF (48g/m² or 1.43oz/yd²) - $$, lightest pure DCF I would recommend for packs, seems really robust and sturdy!, holds stitches well and is easy to work with + seam tape. Fully waterproof.
  • Dyneema Gridstop TPU Laminate (130g/m² or 3.9oz/yd²) - $, quite soft, seems pretty tough, moderately waterproof, could probably be seamsealed
  • PU1000/DWR Woven Melange Dyneema (237g/m² or 7oz/yd²) - $$$, interesting fabric, strong and totally abrasion resistant, quite soft and mellow, not as waterproof as other fabrics, difficult/impossible to seamseal.
  • Venom UHMWPE TPU coated (132g/m² or 3.9oz/yd²) - $$$, feels extremely robust and quite sturdy, highly waterproof, can be seamsealed, some minor imperfections from production are normal, TPU coating is prone to failure over time...
  • Ripstop Polyester 300D (aka HyperD) - (135g/m² or 4oz/yd²) - $, quite soft and mellow, not as waterproof as other fabrics, difficult to seamseal, PU coating might wear off. Good for prototyping because of easy handling.
  • Ecopak Ultra EPL 200 - (119g/m² or 3.5oz/yd²) - $$$, THE current backpack fabric, incredible strong for its weight, easy to seam tape and to handle.
  • Ecopak EPLX 200 - (146g/m² or 4.3oz/yd²) - $, similar to XPac RC but slightly lighter and easier to seam tape, also not as stiff but more smoothly. Choose over XPac.
  • XPac UVX40 - (241g/m² or 7.1oz/yd²) - $$$, interesting fabric, strong and totally abrasion resistant, hard to work with because of stiffness, difficult to seamseal. Might be better suited for haul bags.
  • Ecopak Ultra EPL 100 - (99g/m² or 2.92oz/yd²) - $$$, the lightest Ultra fabric, incredible strong for its weight, easy to seam tape and to handle. My absolute favorite right now.
TLDR: Ultra 100, Ultra 200 and LS07 are my current favorites. I am looking forward to trying a yet to be released even lighter Ecopak DTRS75 fabric though. :)

I would rather advise against these fabrics:
  • 20D SilNylon (36g/m² or 1.1oz/yd²) - $, a pain to work with, not very waterproof and stitches won't hold properly... Stay away.
  • CT2K.18 1oz DCF (34g/m² or 1oz/yd²) - $$, reasonably robust, easy to seam tape, ultralight and feels a bit too delicate. Fully waterproof. Rather use a bit heavier DCF (see below).
  • 70D TPU Nylon - (170g/m² or 5oz/yd²) - $, not as good as the 40D version, tears rather easily, can be seamsealed / welded. Stay away.
  • Cordura + Vectran Ripstop - (410g/m² or 12.1oz/yd² ; 360g/m² or 10.62 oz/yd²) - $, way too heavy, hard to cut and really robust, difficult/impossible to seamseal, not as waterproof.
  • Technora X-Ply Laminate - (100g/m² or 2.92oz/yd²) - $, clear & waterproof, doesn't hold stitches well, hard to seamseal. Stay away.
2) Vest Straps / Harness fabrics
  • 3D HexMesh (405g/m² or 11.86oz/yd²) - $, heavy, rather stiff, great comfort and handling.
  • 20D Monolite / Monofil RipStop (34g/m² or 1oz/yd²) - $, lightest option I sufficiently used, does need a high level of care and might still fail (ripping at the seamholes).
  • 3mm 3D Spacer Mesh (300g/m² or 8.85oz/yd²) - $, reasonably robust and strong, good comfort and handling, not as breathable as the other ones.
  • AliExpress HexMesh (g/m² or oz/yd²) - $, not as strong as the other HexMesh, but way lighter, pretty stretchy (take care with warp&weft!)
  • AliExpress Triangle Mesh (g/m² or oz/yd²) - ($ - not for generic resale), lighter than the Ali HexMesh, but imo more robust and less stretchy! My personal favorite.
Might try some Coolmax Polyester some time, as another lightweight option (120g/m² or 3.54oz/yd²).

3) Stretch / Pocket fabrics
  • Nylon Light Lycra (80g/m² or 2.36o/yd²) - $$, lightest stretch fabric I found viable, still prone to snagging if mistreated, really stretchy!
  • Nylon Sports Lycra (190g/m² or 5.6oz/yd²) - $, really stretchy and rather robust, pretty heavy though.
  • Strong Stretch Mesh / Powernet (160g/m² or 4.72oz/yd²) - $$, really robust and still stretchy, more "seethrough" than Lycra. My fabric of choice for all external pockets!
  • Powermesh Bi-Elast. (110g/m² or 3.24oz/yd²) - $, really stretchy, feels a bit flimsy, still decently robust, may wear out with hard use. Only use for inner pockets.
  • Spandex / Poly Blend (AX Stretch Mesh) (180g/m² or 5.31oz/yd²) - $, moderately stretchy and robust, rather heavy.
  • Dyneema Nylon Ripstop Elast. (230g/m² or 6.78 oz/yd²) - $$$, extremely robust, only low stretch, perfect for the bottom pocket!

To be continued...

PS: It's actually been 30 packs to this date... :D
 

Shewie

Chief Slackpacker
Staff member
Good info thanks

Sadly my DIY skills are nill but it's always inspiring to see what others can do on here.

I've had a few gridstop packs, mostly older ULA and a secondhand Burn, with a decent shoulder strap system I think they're the comfiest to carry, especially with a big winter load, I just need to make sure I have good dry bags inside.
The hybrid DCF Arc Blast did well for a few years, it's looking pretty sorry around the base and roll down top now, signs of delamination and plenty of pin prick holes in the folds, and Feshie mouse damage, but still a favourite.
Got a couple of VX07 packs which I quite like too, feels like a decent compromise of weight vs durability, I haven't used either much yet so not sure how they'll stand up.
 

Montmolar

Trekker
2) Vest Straps / Harness fabrics
  • AliExpress HexMesh (g/m² or oz/yd²) - $, not as strong as the other HexMesh, but way lighter, pretty stretchy (take care with warp&weft!)
  • AliExpress Triangle Mesh (g/m² or oz/yd²) - ($ - not for generic resale), lighter than the Ali HexMesh, but imo more robust and less stretchy! My personal favorite.
Totally forgot to add the weights here haha.

HexMesh: ±224g/m² or 6.61 oz/yd²
Triangle Mesh ±153g/m² or 4.51 oz/yd²
(Diamond Mesh - yet to be tested, only got a sample so far; ±143g/m² or 4.22 oz/yd²)
 

Montmolar

Trekker
Let's continue! For this part I'll only mention what has proven to be the best choice imo - mentioning everything I tried would take waaaay too long. :)

4) Hardware (Buckles, Cord Locks ...)

5) Webbing, Cords and Elastic
5.1) Options for finishing the Roll Top (ordered from most-> least prefered)
6) Tools, Needles and Thread
  • Saxony Tape for seam taping (more flexible and better adhesive vs. DCF tape!)
  • Shrink Tubing for finishing zipper pulleys and cords
  • Schmetz MicroTex 5x70 (not for ultra burly fabric, but leaves the smallest holes i.e. less damage)
  • Nylbond 80 thread (really strong, yet thin thread)
  • Prym Trick Pen for marking (self erasing) or Ultimate Marking Pencil (kinda like chalk)
  • basic seam ripper, lighter, mini roll cutter, scissors, (big) cutting mat and (big) fabric ruler
  • (KamSnap Tool)
  • (Laser for cutting)
 

Jmct88

Trekker
Really useful resource, thank you for all your effort on this!

I saw on Reddit that you may be releasing your pattern (through Bag Buff?) - any updates on this? Would love to have a go making one!
 

Montmolar

Trekker
Really useful resource, thank you for all your effort on this!

I saw on Reddit that you may be releasing your pattern (through Bag Buff?) - any updates on this? Would love to have a go making one!
Yes, I plan on releasing both (big & small version) trough BagBuff but we haven't made much progress so far. :/ Just wrote Stephen Jones again, if he got to checking the pattern yet.
 
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