In temps the same as you mention, I use a wool base layer under a Club Ride flannel. It covers all of the features you are looking for.

 

This

 

FOX Ranger MTB Wind Jacket or Felxair lite MTB Jacket would be my choice.

Using the older Renger wind jacket (without zippered pockets) on cold/windy days and its perfect.

 

Endura Humvee pretty much fits your criteria. Very functional and well made jacket.

 

I just ordered a hooded Humvee and a hooded single track from Endura, looking for something that’s water resistant, and not too hot, more than a windbreaker, but less than the MT 500.

The Humvee hooded is the nicer of the two jackets, softer material, and a less hard shell like texture, both seemed about the same breathability ad had the same venting

Update: Both jackets were more rain jacket shells, not stretchy, so relaly not what I'm looking for, so I just ordered a Leat 2.0, it's a stretchy shell that's 10k/10k.

I sorta realized that the old MT 500 stretch jacket I already owned was a really great winter jacket, so what I need a water resistant windbreaker that stretches ...

 

I buy used high end climbing and hiking jackets off eBay, it’s not bicycle specific but works pretty well and love the stretchy lightly insulated ones. Gear Lab tests them so you can pick and choose which features you want. When you find what works buy two ! GL

 

I have found running jackets to be far more functional and well built than anything MTB specific I've owned thus far... especially regarding "breathability". I'd wager large shoe companies have far more money and R&D into clothing than MTB but that's just a guess on my part.

Also, for me, comfort in moderate temps is all about wind blocking in a lightweight package. Nothing breathes great at those temps for MTB, you're gonna sweat.

 

I struggle with softshells, whether for biking, XC skiing or hiking, I find most of them are not at all breathable and then they're way too bulky to be carrying in a pack.

The best one I've found is the Rab Borealis, which is basically a windbreaker made out of stretchy softshell-type material. It's hooded, which can be annoying for biking, but the hood tucks away pretty well. I use this for XC skiing and biking. It would be perfect if it had some mesh vents on the sides or on the back.

 

I have one of these. I believe it checks all your boxes:

Flexair Neoshell® Water Jacket

Buy Flexair Neoshell® Water Jacket at Fox Racing®

www.foxracing.com

 

$270 on sale, $450 list price.

Dang, that's a pricey piece of kit!

At that price I'd lean toward the Endura stuff, maybe the MT 500 Freezing Point with stretch panels, lots of vents, and super high breathability:

MT500 Freezing Point Jacket II - Black

Buy MT500 Freezing Point Jacket II - Black online with Endura.

us.endurasport.com

 

Sites-Columbia_US-Site

www.columbia.com

 

I would agree that most stuff is not very breathable, that's why I tend to go back to XC ski and sometimes backcountry. I bought an Endura MT500 to have an extra jacket to switch out, but it's been pretty terrible, last winter and this one. Even though it's got more vents than a porsche GT3RS, the material is just too thick and it doesn't breathe. It needs mesh in places instead of the zippers. So it's kind of disappointing.

Last time I rode, I kind of messed up and took my lightest softshell I use for temps 20 degrees warmer than it was. I forgot to check the temp and it was 12 or 16 degrees or something. But it worked out great, I didn't get damp at all. I did put on my outer emergency shell to ride (downhill) home and that was also perfect. I usually will use said jacket in the 15 degree range IF it's a short race, it's perfect there too, but my point is the heavier stuff just doesn't breathe and you can overwhelm it pretty quickly. Bringing the extra layer(s) helps to manage this.

 

I have a windproof from REI. It's REI branded. It checks all your boxes. I don't really care for REI but I will recover.

 

The original poster has obtained a Specialized Alpha Trail jacket.

 

Looks nice. 50-60F is like 10-15C right? With wool baseliner that would be quite warm I suppose.

 

I've been using Ketl Mtn's folly hoodie the last couple winters... a thin softshell that's lightly DWR. I wear it from 45* down to 25* F by adjusting my base layers underneath. Very breathable and works well for me in the Northeast. I don't ride in the rain, but it handles light mist, fog, typical water/mud that gets kicked up on your backside just fine.

 

Ok now that I’ve officially bought backups for wife and I, I’ll share brand and model. Arcteryx fortrez hoody is a great biking jacket thinly insulated but very breathable stretch material w built in balaclava in the hood. I’m 5’10” 185lbs and wear a M have a L also but it’s almost short dress length! We pair it w wool t shirts long or short sleeve depending on temp and mate it with poly cuffed sweatpants. No longer available new but have had good luck w preowned sites as with most of our tech gear.

 

 

The Leavitt Jacket 2.0 showed up in a lovely shade of Pistachio, size XL in "women's"

Woops! But it did fit my wife and it was on sale, so she's keeping it.

The current model is 10k/10 waterproof/breathability, no chest or pit zips, has a mesh interior liner, soft and stretchy, packs down decently for a soft shell, a step up from a wind shell, but not as heavy as a hard shell.

I ordered one for me

 

Finally got a chance to try out the Specialized Trail Alpha jacket. Wearing a long sleeve wool baselayer shirt. Ride started at 65F, ended at 55F. I wasn't uncomfortable at any point and didn't need to zip or unzip the jacket. Wind-blocking is moderate. Insulation (from standing around) is less than a typical "soft shell". This jacket is really good about moving out humidity without causing clamminess or coldness. Often at the end of a ride it's the coldest, but I'm also the sweatiest and so I need a few minutes of just sitting around outside to let the steam out before going back in. No so in this jacket - I was dry at the end of the ride.