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Review: Smith's New Mainline Full-Face Helmet

Aug 25, 2020
by Mike Kazimer  
Smith Mainline helmet review

Seven years after entering the mountain bike helmet market, Smith have finally added a full-face option to their lineup. The Mainline is aimed at enduro racers and riders in search of a lightweight, DH certified full-face with enough ventilation to keep it from becoming uncomfortably hot while climbing.

Smith worked closely with their athletes during the development process to create a helmet that met the criteria on their wish list, which included protection, a comfortable fit, good airflow, and goggle compatibility, all reasonable requests for a high-end helmet like this.

There are two additional color options other than the black version shown here; a sage/red, and the green color used by the Rocky Mountain enduro team. The Mainline is available in sizes S, M, and L, and retails for $300.
Smith Mainline Details

• Weight: 802 grams (medium)
• 21 vents
• Koroyd impact protection panels
• MIPS liner
• Sizes: S, M, L
• Colors: black, sage / red, green
• CPSC, CE EN1078 and ASTM F1952 DH certified
• MSRP: $300 USD


My head measures 58cm, which puts me smack dab in the middle of the 57 – 59cm range that Smith recommends for a medium helmet. There's no twist-dial retention system in the Mainline, but three thickness of cheek pads, two thicknesses of neck pads, and two different crown liners are included. It's worth taking the time to experiment with different combination to ensure the best fit. When I tried the helmet on right out of the box it didn't feel all that comfortable, but within 10 minutes I'd found a pad set up that greatly improved the fit.

I ended up using the thinnest check and neck pads, and the thicker of the two crown liners. I'd put the overall comfort level in between the Troy Lee Stage helmet and the Fox Proframe. The Stage is the best fit for my head shape, while the Proframe is a little tight at my forehead. Of course, helmet fit will vary from rider to rider, but these points might be useful if you have a more oval-shaped head like mine.

One of the key features I look for in a lightweight full-face is how well the chinguard breathes. Most enduro races have at least some climbing in them, and the last thing you want is to to feel all the hot air you're expelling get blown back into your face. The chinbar opening on the Mainline is well placed, and I didn't experience any goggle fogging or stale air recirculation. It's also wide enough to spit through, a feature that comes in handy surprisingly often during a race or hard effort.

As far as overall ventilation goes, the Mainline does a decent job, although the Koroyd doesn't allow as much airflow as a completely unobstructed opening would. That can make things a little steamier on slow, humid climbs, but at speeds faster than crawl I was quite comfortable.

Smith Mainline helmet review
The Koroyd material provides additional impact protection while still allowing hot air to escape.
Smith Mainline helmet review
There's an unobstructed vent at the top of the helmet, and at the back of the head.

My size medium weighed in at 802 grams, a touch more than the 770 gram claimed weight. The TLD Stage and the Fox Proframe are both lighter at 711 and 756 grams respectively, but the Mainline is lighter than the 887 gram Bell Super DH and the 852 gram Leatt DBX 4.0. In other words, it's not the absolute lightest out there, but it's still a very reasonable weight for this type of helmet.

On the trail, it feels reassuringly solid without being heavy – I don't have any weight-related complaints.

Smith were one of the first companies to use Koroyd as a form of impact protection in their helmets, and that material is present in the Mainline as well. Koroyd looks like a bunch of plastic straws that have been trimmed and glued together, and it's designed to crumple during an impact to help reduce the force that's transferred to a rider's head.

Koroyd isn't the sole material providing impact protection in the Mainline, though; the bulk of the helmet is still EPS foam, with a polycarbonate shell over the top of it. There's also a MIPS liner, which is designed to help reduce the force from rotational impacts. The Mainline is CPSC, CE EN1078 and ASTM F1952 DH certified

The Mainline's $300 price tag is right in the ballpark for this style of helmet. For comparison, a Bell Super DH helmet is $300, the TLD Stage is $295, and the Fox Proframe is $250 USD.

Smith Mainline helmet review
A variety of pad sizes are included so riders can achieve their ideal fit.

Other features include a D-ring chin strap closure, and an adjustable visor. Along with the previously mentioned assortment of pads for adjusting the fit, the Mainline also comes with a cloth drawstring sack.

The Mainline is designed to work well with goggles, which makes sense given Smith's extensive eyewear collection. There weren't any fit issues with the Smith Squad XL goggles I used, which are on the larger side of the spectrum.

Just like with the TLD D4 I recently reviewed, the MIPS liner in the Mainline can make a distracting creaking noise as it rubs against the inner portion of the helmet. This was more noticeable when climbing – once I put my goggles on to descend the the helmet rotated a little less on my head, and the noise subsided slightly. Humidity and head shape can play a role in how much noise MIPS makes, but still, I wish it was quieter. There are other versions of MIPS out there that have a soft fabric sticker between the plastic liner and the foam – perhaps that could be the ticket to quieting down future versions of the Mainline.

Smith Mainline helmet review
Smith Mainline helmet review



+ Comfortable, customizable fit
+ Very reasonable weight

- Creaky MIPS liner

Pinkbike's Take

bigquotesIt took a while, but I'd say Smith's delayed entry into the full-face world was worth the wait. The Mainline hits the mark when it comes to overall comfort, although, once again, I wish the MIPS liner didn't make any noise. Otherwise, the Mainline's a great choice for riders looking for extra protection out on the trail while still maintaining a reasonable level of ventilation. Mike Kazimer

Author Info:
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Member since Feb 1, 2009
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  • 91 2
 pair a creaky helmet with a creaky bike and you’ll go insane. It’s a scientific fact. it’s science.
  • 69 1
 The only thing worse than your bike creaking is your buddy's bike creaking.
  • 68 3
 Too bad nobody listens to science anymore
  • 18 0
 @N-60: I just tortured my brother for 3000' of climbing on climbing on Sunday with a howling bb.

He pitched a wrench at me when we got back to trail head.....definitely deserved it
  • 7 6
 @bandit350: what has science done for me lately?
  • 16 1
 @deepstrut: it definitely didn't give you the dopamine hit that being a science denier gives you when you manage to interpret everyone yelling you down as a moron actually means that you are the special one who knows something the masses don't Rolleyes
  • 3 1
 @freestyIAM: they should bottle that feeling and sell it. I want a hit of that good good
  • 8 0
 @deepstrut - i'm pretty sure science made PB possible, along with your ability to comment here.
  • 5 0
 Science- wha's it all about? Techmology- what it's all about? Ees it good? Or is it whack?

  • 2 0
 In mother Russia, science does you.
  • 1 0
 Couldn't you put a thin strip of felt or 2 between the MIPS and the shell to quiet it like the material they use for camera wind noise?
  • 3 4
 @blowmyfuse: it’s a lot easier, and cheaper (and probably at least as safe to not buy a mips helmet....the science behind it seems as wack as wearing a mask outside on a sunny day.
  • 7 0
 @Remedy808: one time I rode with a guy that had never lubed his chain. and that's the story of how I ended up serving consecutive life sentences.
  • 2 0
 @deepstrut: Science also gave you a sweet bicycle with nice parts and suspension, that have been evolving and improving for 30 years with testing and innovation.
  • 4 0
 @unrooted: Helmet science is a moving target, figuratively and literally. I can't imagine designing anything that is supposed to coddle a sponge inside an eggshell that gets chucked at rocks by John Cena takedowns.
I'm glad they're trying at least since I've been lucky on the brain buckets in my life. Only reset my skull once when I was 15. Still can hear myself talking nonsense that day.

Got a D4 w/ MIPS & Leatt for my wife that had those rotating pucks in it. Neither seems ground breaking but for the money we pay, can't expect more
  • 1 0
 @deepstrut: lately or every moment of every day, science is life, without you’d still just be a twinkle.
  • 2 0
 statistics show that people do not like creaky products, we did the math
  • 30 0
 So I have this helmet and did a 6000m descending day yesterday with about 800m climbing. Overall I'm happy with helmet and it is a big step up from my former full facer. I have a 58.5cm size head and got the L. I am using the medium pads which are quite tight on the cheeks and very little bit loose around the forehead. I will put on an additional thin padding around the inseide and that will be fine.

1) The creak is more a thing you notice in the carpark than anywhere else. I forgot about it after 10 min. During the descents I didn't notice it once. Climbing likewise. Don't sweat it.
2) The thing is super well ventilated and I did all the climbs with it on. I could feel a cooling air flow as soon as I went a bit faster and it really didn't get too hot. This feature is a really good aspect.
3) I had my goggles on the the helmet all day and I could keep them under the visor - which I moved into the highest position- and virtually out of sight during the climbs...My goggles even have stupid large corners at the bottom which I could see slightly during climbs but were entirely unproblematic.
4) No fidloc...yeah...a missed opportunity I concede, but the 6000m were 4 descents so it can be tolerated at that frequency.
5) The helmet looks pretty well built without the feeling of being covered in cheap plastic.... but
6) after this first day the hard inner lining on which the cheek pads sit has already begun to come off from the chin bar and I will need to glue it in place. ... that's lame.
I also didn't pay 300$ for this and it was significantly reduced where I bought it (snowleader.ch).

that's it.
  • 5 0
 You got a big head man
  • 38 11
 Looks like it’ll be a great helmet, my only complaint is the D-ring closure, after using a Fidlock buckle for a few years I don’t think I’d be able to go back
  • 8 0
 The creaking is a real problem though. I've had a mainline for awhile and while the fit is great and the weight isn’t too bad at all, it the mips liner sounds like the noisiest paper bag in existence. It’s a real shame, as otherwise the helmet is super comfortable and would be ok for even for long rides (I have done a few solo 30km+ rides with it), but at some point you start feeling your level of sanity decline. Like the review says, it’s not too noticeable downhill, but it certainly starts grating on your nerves during climbs and pedally sections.
  • 14 14
 It's hard to believe that Drings buckles are still present on 300$ helmets and not listed in cons. My 95$ O'Neal has a fidlock, wouldn't go back to anything else
  • 44 5
 D ring closure is a must on downhill certified helmets as its the only approved closure on races. It's easy to handle, nearly indestructible and especially easy to open for rescue personnel.
  • 13 1
 D-rings are tried and true. There's been a lot of attempts at overthrowing it but none have been able to match D-rings...until fidlock. D-rings are still great in my opinion as they check all the boxes including inexpensive to implement, but as @Whipperman said for $300 it should be on there.
  • 15 2
 @danimaniac: agree completely, would never even consider a full on DH lid without D links.
  • 6 0
 The big thing for me with D lock is the length of the strap. I've had helmets before where the strap is so short you have to completely remove it from the D rings to remove it, however with a longer strap you can just loosen it to remove the helmet then when putting it back on just give the strap a quick cinch rather than fiddling about re threading.
  • 2 5
 I'm still fiddling with my fidlock cause I have 4 different helmets with 4 different type of closures. I never even got the hang of D rings either and associate it with claustrophobia and sweat.
  • 7 1
 @danimaniac: Emergency personnel will likely cut the straps, no matter what buckle it has.
  • 11 2
 @bicyclelifestyle: Just because they want to use their special emt rescue knives.
  • 4 0
 @DoubleCrownAddict: I would guess because they dont want to cause any futher damager to your spinal cord. Cut my helmet off so i can hopefully keep the use of my lower body? Any day of the week.
  • 3 16
flag DoubleCrownAddict (Aug 25, 2020 at 10:23) (Below Threshold)
 @bicyclelifestyle: Cutting the straps is going to jostle around a helmet much more than simply unclicking it. Last time I was in the hospital they unnecessarily destroyed my $100 bib shorts removing them. EMT doesn't always go about removing things in the ideal manner, they destroy everything cause that's what they are used to doing and it requires the least amount of thought.
  • 7 0
 @DoubleCrownAddict: I've only ever seen them use scissors and there is no jostling.
  • 2 0
 @danimaniac: I never heard D-rings being required before. Do you know who requires them? Asking because my Leatt DBX 5.0 has fidlock even though it's downhill rated etc etc....
  • 13 0
 @DoubleCrownAddict: $100 bib shorts, boo hoo.

Life > stuff.

And it's just stuff. They don't care how much you spent on your stuff and you shouldn't either. They are saving your life.
  • 1 8
flag DoubleCrownAddict (Aug 25, 2020 at 15:15) (Below Threshold)
 @bicyclelifestyle: Not even close, they just put some stitches in my leg. Should have just skipped the visit and used superglue.
  • 4 0
 @chadtague1: I've now spend half an hour digging for my source of this information and I remember it came from a guy from a rescue team.
Anyway, couldn't find it. ASTM norm pdf is 44$ and that's not worth it and in the uci rulebook only days downhill certified helmet with chinguard.
So... It might not be mandatory (anymore) to use a double d-ring closure in dh races.
  • 12 0
 Big fan of my IXS trigger FF, lighter, cheaper, fidlock.
  • 2 0
 The Trigger has been awesome.
  • 8 0
 Mike do you think a quick squirt of well placed silicon spray will stop the mips creaking? It's definitely my go to product for friction creaks on basically anything. It's also safe to use on plastics, vinyl, metal etc... Some varieties of Silicone Spray like H4000 are even food grade.
  • 4 7
 Or, a couple drops of glue....
  • 24 0
 Introducing Muc-off's new line of I Can't Believe It's Not Butter Silicone Helmet Spray specially formulated for Mike's with creaking MIPS liners!
  • 18 0
Yeah, glue that creaky mips in place so it doesn't move anymore
  • 4 0
 @slovenian6474: Just 39.99 for 1.5oz!
  • 5 0
 I bought this a couple weeks ago. I tried on all the FF helmets and the mainline was definitely the most comfortable for my head anyways bought a size Large. I don’t notice the so called squeaky noise while riding. And was stoked that it had a regular D-ring strap. Coming from Moto it just feels natural for a helmet!
  • 3 0
 At least this has a moving visor, which is my biggest gripe about my Proframe. Overall I think I still prefer my Kali Invader - Lighter, vents everywhere, Fidlock buckle AND lifetime crash replacement policy. While it may not pass DH Certification due to the amount of venting, it passes motorcycle helmet chin bar rating which is good enough for me. Fortunately the Enduro races I ride here in the UK don't require DH Certified helmets to race. It's a great choice for big days out where the trails are rough and rocky and there is a fair amount of climbing to be done.
  • 1 0
 Love my Invader... I use it for every now it's so comfortable and cool. Pro-tip: for long climbs on really hot days... pop out the cheek pads and throw them in your pocket... it vents so well it feels like a half shell. Then just pop them back in when that big hot climb is done. I don't have to do that often... but during the heat wave a couple weeks ago, it was really nice.
  • 1 0
 @islandforlife: on a long climb, put that helmet on your back and put on sun hat, way cooler than any helmet
  • 1 0
 @nurseben: Haha... where do you keep the sunhat?
  • 2 0
 Actually, Smith's first fullface helmet was a limited edition Troy Lee collab on the D2 and came in some pretty awesome color combos, which probably makes it the rarest D2 out there. It was marketed as a freeski helmet for their big mountain team.
  • 2 0
 Just purchased this helmet last week. Did notice the creaking but I guess I got used to it. The fit and comfort is good for me. But after my first ride with it I noticed that the screw had fallen out on one side attaching the visor. Pretty unacceptable for 300$ and I had to file a warranty claim which they say takes 3-4 weeks to process.
  • 2 0
 Love all the new light weight FF with DH rated hats. After seeing a friend eat some hard pack and medievacing on some easy trail going just 17mph, I would be pleased to not be the only one wearing these FF on trails less than gnarly.
  • 3 0
 YES! first photo is of sombebody actually wearing the thing.
@mikekazimer can you store goggles on the forehead below the visor?
  • 1 0
 "There are other versions of MIPS out there that have a soft fabric sticker between the plastic liner and the foam – perhaps that could be the ticket to quieting down future versions of the Mainline."

I have a Fox RPC MIPS, which has these felt pads. It creaks too. Would rather no MIPS if I'm honest.
  • 2 0
 I have a surprisingly large pile of extraneous bags that came with every pair of sunglasses and helmet I've bought over the years. So unneeded, manufacturers should stop including them.
  • 3 0
 Smith customer service is atrocious. That lifetime warranty is matched with weeks of waiting for a response and or sitting on hold for hours. No thanks.
  • 1 0
 I bought this helmet about two weeks ago after trying on Giro and Bell hybrid FF helmets and the Troy Lee Stage. Both the dedicated FFs were *way* more comfortable than the Giro and Bell (both with traditional bike helmet rear dial adjustment), and notably lighter and better ventilated than any of the FFs I've tried on or owned in the past (which were close to my moto helmets in scale but less protective and well finished).

The Stage seemed a little better ventilated, especially at the ears, but the Mainline was marginally more comfortable for me. The fit is a little round for my oval head, but still very very good. I would have been happy with either and had a hard time deciding. Have ridden with the Mainline several times since and very happy with it. Good enough to take the fullface on trail or shuttle rides, which I wouldn't have done in the past, and considering I already have a good open face helmet, I don't see the allure of a heavier and less comfortable hybrid/removable full face.
  • 4 1
 I just bought this helmet and returned it because of the squeaking sounds. Smith didn't reply to my email so back it went. It's super annoying.
  • 1 0
 I would love to see some kind of a empirical rating system for helmets that translates easily to the type of riding mountain bikers do. I know there is the Virginia Tech ratings, and those are helpful, but being able to look at objective safety measures for a helmet free of buzz words, proprietary tech etc. with a direct relation to the type of riding and injuries most MTBers are most privy too would be nice. Judging just by the Virginia Tech ratings, the Koryd tech used by Smith doesn't seem to do all it was advertised and many helmets without both rate as safer in their tests. The old metric of "buy a nice helmet" which many translate to "buy an expensive helmet" doesn't really hold weight. Would be nice to compare comfort, objective safety, cost etc. without all the guess work still part of buying a new helmet. That TLD scores high...
  • 8 4
 Why does every new light fullface come with a glory hole ?
  • 10 0
 To look out of?
  • 1 0
 the creak would annoy me a tad...then again when the air is whooshing past, when riding i bet it will not be noticed....Wonder if the creek gets really loud when you fall off. I have the IXS which is really good.
  • 5 1
 Why is it so hard to make Holes for the ears into Ff helmets?
  • 1 0
 Kali Invader...
  • 1 0
 And the tld stage
  • 1 0
 I’m curious that the Stage fits your oval head well. I have an oval head as well and the TLD A2 does not fit well - tons of space beside my head as it seems to fit a round head better.
  • 1 0
 Id be worried about being impaled in the chin with that huge hole. I get its supposed to be breathable but id rather just wear a regular dh helmet with more coverage if im gonna wear one at all.
  • 1 0
 Finally some more brands are mixing in up in the full face enduro helmets. FOX and TROY LEE really need to step up their game. I never understood why chinbars have jagged edges.
  • 1 0
 For my head,the Mainline is the most comfortable full face. I tried on a Stage and immediately got a headache. The Proframe wasn't bad, but this was better.
  • 3 0
 Bell Super Air R. Love it! Tons of climbing in Sea to Sky corridor.
  • 1 0
 No Xl for my ridiculously big noggin makes it a deal breaker. Tried a large on this past weekend and it wasn’t even close. Bummed. Stage it is for me
  • 1 0
 Crashed hard twice in Finale last week and the helmet done its job, however I need a new one.

Do they offer crash replacement on the mainline?
  • 1 0
 a Proframe and an IXS had a son with the visor problem fixed
  • 1 0
 Proframe is best-looking helmet ever made
  • 1 0
 Does the TLD Stage creak as well?
  • 2 0
 Mine does a bit, but only if I move it around intentionally. Wrong angle or itchy spot on my head or whatever, not while I'm riding.
-pro tip: I got it directly from TLD website for 50% off as it was a previous year's colour.
  • 1 0
 I just got my Stage yesterday and it doesn't creak.
  • 1 0
 Mine doesn't
  • 1 0
 Ok, good to know. Thanks folks.
  • 1 0
 Mine doesn't.
  • 1 0
  • 1 0
 Y'all a buncha big hedz
  • 1 0

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