Arc Teryx Atom lt vs Proton lt

I was wondering what the difference is between the Atom lt and the Proton lt.  Does anyone with experience using both have an answer? It looks like the proton is a newer version of the atom?  

Proton LT breathes very very well, almost as much as a nano air. Also stretches. Atom LT doesn't stretch and basically doesn't Breath except it let's wind through the side panels.

I've had an Atom LT. Didn't like it, despite pretty much every review raving about it.

Like any other hybrid, it tries to do two things well (insulate and breathe at the same time), and it fails at both. Arcteryx claim that the fleece panels on the sides help with ventilation, but I've found that if you're working hard enough to sweat, you'll be sweating with or without the panels. Honestly, all those fleece panels ever do is let wind through. Arcteryx say to put on a wind shell to stop that from happening, but what's the point of having breathable side panels if you're going to cover (thus reducing the breathability even more) them anyway? I just don't get it. Hybrids are stupid.

The Proton LT doesn't fit me (too tight in the shoulders), so can't comment on the performance. If you must choose between these two models, go for the Proton. The Atom is just wank.

^^^Yup. If we didn't make it clear, the proton doesn't block much wind, about the only downside if that is what you need. The atom blocks most wind but on cold days they still let in all that cold air and so it sucks. I also feel like the proton is slightly warmer.

Would there be another jacket other brand that makes active insulation that is recommended.  Patagonia, Rab, etc.  

Take a look at Mountain Equipment

The Proton is newer than the Atom, but they are different jackets.

The Atom has slightly denser face fabric and does not breathe as well as the Proton. However, the main fabric is more wind resistant and more water resistant, keeping in mind that there are fleece panels under the arm that are neither.  

The Proton is designed to be very breathable insulation that can provide wind/water resistance past the point of a fleece, but not as much as a soft shell. The main benefits are it’s breathability, light weight and small pack size while still keeping you warm when needed. 

I don’t think the Atom LT has more Coreloft in it than the Proton LT, but it is 40g heavier.

I have an Atom LT vest and wear it over a base layer on long winter runs - but only if it’s below freezing and/or it’s my long slow run. I also carry it (along with a Gore Paclite) as an emergency layer on some long rock climbs if I’m going too light to take a real puffy jacket.

Arc'teryx released their updated Proton LT this fall with a different insulation, CoreLoft Compact, which is different from the previous generation's CoreLoft Continuous.  They also used a 20D face fabric vs the previous generation's 40D.  According to Arc, this new combination of "updated" insulation and a lighter fabric makes their newest Proton much more breathable.  The change in insulation allows the jacket to be more packable as the previous generation is a bit bulky when stuffed in a pack.  The jury's still out on relative warmth as the newest version Proton was just released.  

CoreLoft Compact is comprised of "highly crimped fibers," which allows it to pack down better, but isn't as durable, nor as warm, when compared to the previous generation's CoreLoft Continuous fill, according to Arc'teryx. I own both a Nano-Air and Proton LT Hoody, and if breathability is more important, go with a Nano-Air.  Keep in mind, I have yet to wear an updated Proton, though. I like the fact the Proton LT's hood is helmet-compatible (over the helmet), vs the Nano-Air Hoody, which is under the helmet.  I don't know why manufacturers design hoods to be worn under the helmet vs over the helmet.  It's so much easier to regulate temperatures by just donning/doffing a hood over the helmet.

Sunny-D wrote: Would there be another jacket other brand that makes active insulation that is recommended.  Patagonia, Rab, etc.  

Patagonia Nano Air Light is amazing from personal experience. Warmer than it seems as well. I hear good things about North Face Ventrix as well

Cool thanks.  Good information.

An option you can find for half off would be the north face ventrix.  Stretches better than the proton imo.  The atom seems better for stagnant or slower activities compared to the proton.  

All said-I use the ventrix for higher output activities like biking. Similar for the mountain hardwear kor.  Then the proton or-atom for colder ice climbing days or as a mid layer for mountaineering. The acto is a better overall single layer imo but doesn’t layer as well over other pieces. 

AlpineIce wrote: Arc'teryx released their updated Proton LT this fall with a different insulation, CoreLoft Compact, which is different from the previous generation's CoreLoft Continuous.  They also used a 20D face fabric vs the previous generation's 40D.  According to Arc, this new combination of "updated" insulation and a lighter fabric makes their newest Proton much more breathable.  The change in insulation allows the jacket to be more packable as the previous generation is a bit bulky when stuffed in a pack.  The jury's still out on relative warmth as the newest version Proton was just released.  

CoreLoft Compact is comprised of "highly crimped fibers," which allows it to pack down better, but isn't as durable, nor as warm, when compared to the previous generation's CoreLoft Continuous fill, according to Arc'teryx. I own both a Nano-Air and Proton LT Hoody, and if breathability is more important, go with a Nano-Air.  Keep in mind, I have yet to wear an updated Proton, though. I like the fact the Proton LT's hood is helmet-compatible (over the helmet), vs the Nano-Air Hoody, which is under the helmet.  I don't know why manufacturers design hoods to be worn under the helmet vs over the helmet.  It's so much easier to regulate temperatures by just donning/doffing a hood over the helmet.

Can I get an AMEN!  Under the helmet hoods for these jackets are the most annoying thing.  It's so close to perfect but that hood is almost unusable!

Two things:

1 - the new Proton that AlpineIce is speaking about is selling well in my business right now and the feedback has been great.

2 - the Summit L3 Ventrix 2.0 is a great value for money and is the most popular of the jackets mentioned in this thread so far. 

Matt S. wrote:

Can I get an AMEN!  Under the helmet hoods for these jackets are the most annoying thing.  It's so close to perfect but that hood is almost unusable!

I wear the hood on my Patagonia Nano Air over the helmet (Grivel Stealth). Not really designed to be used like that, but it's stretchy enough to work well for me.

Throwing another contender in here... the Ortovox Swisswool Zebru jacket.
I have The Arc’teryx Atom and last years Proton. The Atom was a great piece when it came out years ago but does not wick or breathe very well thus the move to Nano and Proton type jackets by the industry.
I find that the Ortovox Zebru breathes at least as well as the ( last year) Proton and is lighter by a few ounces.
I used the Zebru in a wide range of conditions last year and over 80 days and it is one of my go to favorite pieces of gear. No sign of wear or insulation packing out or shifting.
Highly recommend!

Sunny-D wrote: I was wondering what the difference is between the Atom lt and the Proton lt.  Does anyone with experience using both have an answer? It looks like the proton is a newer version of the atom?  

I have experience on both. I had Atom LT and sold it away. Almost the only Ryx product I did not like. I love other Atoms, but LT is confusing. I often felt hands sweating while torso getting cold. This was not a problem with SL with similar side panels as those blocked more wind. All other aspects of Atom LT were great, awesome Ryx quality as always. The problem was design, which required far too much fiddling for me.

Proton LT (mine is the older one) has more trim fit and a useable chest pocket. Hem adjustment is genius, hood is great and long arms help on alpine activities. Design is better than Atom, with uniform air permeability. Breathability and warmth is somewhat less than Patagonia’s seminal Nano Air, though. I still much prefer Proton’s fit. I like other aspects so much that I’m looking at the upgraded model later next year.

No perfects mid range jacket exists yet, or at least I’ve not seen one that adequately combines the best things from the best. Nano Air has superior air permeability, but has known durability issues and the fit is boxy. Atom LT is confused, while wears arguably nicely. Proton, at least the old one, is a fortress and fits well, but breathes far less than Nano Air. I run warm and cool quickly, so finding just the right materials and fit feels hard.

Depending on your preferences, I’d look into newer Proton LT and OR Ascendant Hoody. For lighter uses Atom SL and the new Proton FL (getting one tomorrow!) may be enough, with some grid fleece. Discontinued Proton AR was excellent for colder temps.

Ryan Williams wrote: Two things:

1 - the new Proton that AlpineIce is speaking about is selling well in my business right now and the feedback has been great.

2 - the Summit L3 Ventrix 2.0 is a great value for money and is the most popular of the jackets mentioned in this thread so far. 

I once tried a Proton LT and absolutely despised how the zipper would just open on its own if half zipped. So it was either full, or almost totally unzipped. It was such a cheap part of such a fancy jacket. Do you know if the 2019 has updated it?   My RAB Alpha Direct jacket is nearing EOL and I need a new insulated piece that is for cold winter bike commuting, hiking and similar high output activities that *also* maintains some decent warmth when I'm standing still (eg can be used as a "belay" jacket in a pinch).  

I know this is a goldilocks ask, but if the new Proton LT has that quality, I'm into it.

Boris Tucano wrote: I once tried a Proton LT and absolutely despised how the zipper would just open on its own if half zipped. So it was either full, or almost totally unzipped. It was such a cheap part of such a fancy jacket. Do you know if the 2019 has updated it?   My RAB Alpha Direct jacket is nearing EOL and I need a new insulated piece that is for cold winter bike commuting, hiking and similar high output activities that *also* maintains some decent warmth when I'm standing still (eg can be used as a "belay" jacket in a pinch).  

I know this is a goldilocks ask, but if the new Proton LT has that quality, I'm into it.

New model is the same. No locking zipper. That said I've never had an issue with it sliding when I didn't want it to, and it's nice to know I can just yank on the jacket to open it up if I'm too busy climbing to search for a zipper pull.

Got it, thank you!

The “easy slide” zipper is intentional by Arcteryx... they said it’s to protect the flimsy fabric from being ripped by just letting the zipper give. 

zimick wrote: Throwing another contender in here... the Ortovox Swisswool Zebru jacket.
I have The Arc’teryx Atom and last years Proton. The Atom was a great piece when it came out years ago but does not wick or breathe very well thus the move to Nano and Proton type jackets by the industry.
I find that the Ortovox Zebru breathes at least as well as the ( last year) Proton and is lighter by a few ounces.
I used the Zebru in a wide range of conditions last year and over 80 days and it is one of my go to favorite pieces of gear. No sign of wear or insulation packing out or shifting.
Highly recommend!

I just picked one of these up on deep discount. Its a nice jacket. Compared to the new Proton LT I would say

1.) Its a half size smaller, so if you go up a size, it will be a half size larger. Makes sense if you are between sizes with Arc'teryx.
2.) The exterior material feels less durable than the Proton LT.
3.) It does not feel as warm as the Proton LT, its pretty close to my Atom SL but with insulation in the arms, so sort of in-between those two.  
4.) The cut is more 'average' that is, narrower in the shoulders with a bit more room in the mid-section. Not quite Patagonia'eque but about half way between those two cuts. 
5.) It feels lighter and stretchier than the Proton LT.
6.) The hood is under-helmet instead of over helmet. I actually prefer this for climbing in the cold.

Im not sure I am going to keep it so if someone is interested in a deep discount on a L, msg me.