BMC's All-New Fourstroke Has a Self-Dropping 'Automatic' Seatpost

Oct 5, 2022
by Seb Stott  
photo

BMC have released an all-new Fourstroke, their full-suspension cross country platform. The biggest news is the race-ready Fourstroke 01 model has what BMC call "the first ever fully integrated, automatic dropper post."

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Pinkbike photographer Andy Vathis spotted this prototype version back in 2019.

By "automatic", they mean it can extend and drop at the push of a button, without the rider having to compress the seatpost manually by squatting down on the saddle. BMC call this Autodrop, and the advantage is obvious. Come into a descent and need the saddle out the way? Just press the button and it's gone. No need to stop pedalling, squat down on the saddle and stand back up before you can attack the descent. That's probably not a big deal to the average rider, but used many times over the course of a World Cup race it could add up.

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bigquotesDuring a race, we activate Autodrop up to a hundred times allowing us to focus entirely on the track and giving us the gold-medal-winning advantage.Titouan Carod, BMC MTB Racing Team

A normal dropper post gets the energy it needs to return from a spring, which is compressed by the rider pushing down on the saddle. In technical engineering terms, dropper posts are ass-powered. BMC's Autodrop post, however, is air-powered. There's a tank of compressed air in the down tube, which is inflated via a Schrader valve to 14 Bar (200 psi). When the remote button is pressed with the saddle up, the compressed air pushes on a piston which forces the post down and compresses a small coil spring. When the button is pressed again, the air is released and the coil spring returns the post to the extended position.

photo

BMC say the seatpost can do this up to one hundred times; when the pressure drops below 4 Bar (50 psi), it can no longer drop automatically, but it will still function like a regular (ass-powered) dropper post. BMC say that "During a race, BMC riders activate Autodrop up to a hundred times", suggesting they might use the full Autodrop capacity over a long race, perhaps finishing with effectively a "normal" dropper.

The seatpost offers 80 mm of travel and only has a high and a low position - it cannot be set to an intermediate height. There's no word on the weight, but it's based on BMC's RAD seatpost, which shares the same integrated design and oval cross-section. That post is claimed to weigh just 345g, but BMC admit the air tank alone adds 120 grams to the frame weight.

Paul Foulonneau 3SO L Agence
Paul Foulonneau 3SO L Agence

The top-spec Fourstroke 01 LTD's total weight is claimed to be 10.5 kg (23.1 lb). That's not the lightest by race bike standards, but the company acknowledges this. They say their dual-link APS suspension system is heavier than the flex-stay-single-pivot layout that's become nearly ubiquitous in the category. But BMC say their approach more than makes up for the weight penalty: "Extensive testing shows that the Fourstroke and APS suspension are faster than lighter bikes that feature weight-saving suspension systems, proving that superior traction and pedalling efficiency are more important than weight." Obviously, take any company's claims of "extensive [internal] testing" with due scepticism, but it's interesting to see BMC openly sacrifice lightness for overall performance in the XC category, both with the suspension design and the Autodrop feature.



Models

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The top-of-the-range Fourstroke 01 LTD

BMC's naming convention is more than a little confusing. The Fourstroke 01 is the no-compromise race bike, and is the only model to use the integrated Autodrop seatpost. It has 100 mm of travel at each end, with 32 mm stanchion forks. There are three spec levels under the Fourstroke 01 banner, all of which offer Autodrop. These are the Fourstroke 01 LTD (€ 12,999), the confusingly-named Fourstroke 01 ONE (€ 10,999), and the Fourstroke 01 TWO (€ 8,999). There's also the Fourstroke 01 FRS V1 frame, shock, fork and seatpost (€ 5,499).

Paul Foulonneau 3SO L Agence
The Fourstroke ONE. (Not to be confused with the Fourstroke 01, obviously.)

Then there's the Fourstroke (minus the "01" part). This is similar to the Fourstroke 01, except it has a regular 31.6 mm diameter (round) seat tube, and so cannot take advantage of the integrated Autodrop or RAD droppers, which both have an oval cross-section. There are four spec levels: ONE (€ 7,499), TWO (€ 6,499), THREE (€ 5,299) and FOUR (€ 4,299).

photo
The Fourstroke LT LTD

Finally, there's the Fourstroke LT, which of course stands for long travel. With a longer shock and fork, it delivers 120 mm of travel at each end but is otherwise similar to the regular Fourstroke. There are three spec levels: LTD (€ 11,499), ONE (€ 5,899) and TWO (€ 4,499).



photo

Geometry

All three versions have similar geometry. For an XC race bike, the numbers are decidedly on the progressive side, with a 66.5-degree head angle and a 76.7-degree seat angle. The frame geometry of the Fourstroke and Fourstroke 01 are identical, though the cockpit proportions of the 01 are more aggressive. The LT version is near identical too, with no change to the frame angles. Instead, a longer fork and shock create a 15 mm increase in bottom bracket height when the suspension is fully extended.



Availability

The Fourstroke 01 LTD and ONE are available from June 2023, TWO from October 2022 and FRS VAR1 from February 2023, and cost 12,999 (13,499 USD), 10,999 (11,499 USD), 8,999 (9,499 USD) and 5,499 (5,999 USD) euros respectively.

Fourstroke ONE is available from October 2022, TWO from April 2023, THREE from June 2023 and FOUR from September 2023, and cost 7,499 (7,999 USD), 6,499 (6,999 USD), 5,299 (5,799 USD), and 4,299 (4,699 USD) euros respectively.

Fourstroke LT LTD is available from April 2023, ONE from January 2023 and TWO from September 2023, and cost 11,999 (12,499 USD), 5,899 (6,399 USD), 4,499 (4,999 USD) euros respectively.

For more information, check out bmc-switzerland.com.



Paul Foulonneau 3SO L Agence


Author Info:
seb-stott avatar

Member since Dec 29, 2014
306 articles

261 Comments
  • 594 1
 One-One was a race horse. One-Two was one too. One-One won one race and One-Two won one too.
  • 47 3
 Why isn't your username Dr_Suess?!?! absolute gold
  • 20 0
 F yes, EXACTLY, thank you for the clarification
  • 8 100
flag rideordie35 (Oct 5, 2022 at 9:32) (Below Threshold)
 Nah don’t like it
  • 85 3
 But then One Two won one more. So One Two won one more than One One and One One must win one more to have two wins too, like One Two.
  • 22 0
 @hotpotato: I'm sure One One wants two, too.
  • 27 0
 But I STILL don't know Who's on first!
  • 8 1
 Lufthansa flight LH2222 to Toulouse is now boarding.
  • 8 0
 @ullsen: don't hurry, it's always delayed
  • 5 0
 @ratedgg13: I'm over here tripping wondering Who is The Band on stage?
  • 2 0
 @JSTootell: Animaniacs deep cut?
  • 2 0
 I believe you've just won PB
  • 5 0
 @pmhobson: Boomers got Abbott and Costello, Gen X got Slappy and Skippy
  • 5 0
 Is that some kind of binary joke?
  • 3 0
 Two boys went out in a boat, one named Pete the other named Repeat, Peat fell in; who was left?
  • 3 0
 But did One-One win one before One-Two won one? And now that each One has won one the question is which One will win one next?
  • 6 0
 @likeittacky: Steve Peat
  • 1 0
 Let's get this one up two 420.
  • 1 0
 @likeittacky: Inchme and pinchme went out in a boat. . .
  • 1 0
 Three three had to pee. He didn't make the race.
  • 3 0
 @CSharp: Binary joke? I've seen zero on PB... but this might be one.
  • 1 0
 @rrolly: The pelican the pelican his beak holds more than his belly can and i don't know how the hell he can!
  • 93 1
 I have been waiting for this!The rhythm that you lose by having to stop pedaling, sitting down, into a low position and standing back up. I hope more XC oriented droppers go in this direction.
  • 36 2
 Agreed so much as an XC racer boi. I try to explain to my endurobro friends on why this is wanted as they are like "just squat down on it"..

Stopping pedaling to use my weight to drop the dropper multiplied x's probably 25x's per lap , x'd 3 laps = I just tend to not use the dropper in races and only in casual riding.

Now the question of reliability will remain to be seen with bmc.
  • 29 2
 The best part of this is that in the last picture, the dropper post is still up. It's clearly very useful, but only if the rider actually uses it Big Grin
  • 31 1
 @mackster23: with 80 mm of drop, I’m not ruling out that the post actually is down
  • 3 1
 I mitigate this by dropping it on my way to standing up in the first place.
  • 1 0
 @LaXcarp:
thats exactly what he described with more words Razz
  • 4 5
 I find that MOST (not all) who struggle with this issue just aren't practicing enough. It really takes near zero effort when timed right.
  • 10 0
 @combfilter: "Just squat down on it" is the name of my new rap album.
  • 6 0
 @JSTootell: yes, on a trail ride with friends no problem, but in a race everything becomes that much more when your heart rate is redlining.
  • 2 0
 There’s got to be a way to air up the tank as the rear suspension cycles. Add a mini pump. Not that I really care.
  • 3 1
 @txcx166: it's a race bike so as long as there are enough cycles to cover a vast majority of your race, who cares how you refill it. IF you wanted to modify the concept to Enduro racing you would have more stroke so less cycles per air tank but shorter race time. Refill it while waiting for the next run with a shock pump as you suggested. For recreational riding, I don't want to waste time refilling the air tank so go with the "traditional" "ass powered" post.
  • 3 0
 You really need to try a Transfer SL, it's so light that you barely need to apply weight to it, it also returns VERY fast, i now find myself using it only for a few seconds, it has been a game changer on races
  • 2 4
 @mrkkbb: While on the back end of the pack, I do still carry a Pro XC license. I am pretty well versed in what it is like to be at redline.

Practice more.
  • 1 0
 Just pedal a bit harder into the section you are going to drop it for, in the end no loss of overall speed.
  • 4 0
 this will be so useful on my office chair
  • 1 0
 @marcoaml78: yea, i have one and it's amazing
  • 1 0
 @JSTootell: It has nothing to do with practise, we are not saying it's difficult to do it.

The last thing you want to do when your legs are burning, is to do a squat.
  • 75 0
 Dear BMC, Thank you for sending the cables NOT through the headset. Seriously. Much appreciated.
  • 5 0
 Actually. I’m surprised a brand that’s known for integration and that sort of thing such as BMC didn’t go that route!
  • 68 0
 The naming convention couldn't be worse. You can get a Fourstroke 1, One, or a Fourstroke One, or a Fourstroke LT, One, or a Fourstroke Lt, LTD, or a Fourstroke 1 LTD. So Dumb.
  • 286 0
 i suffered four strokes reading that
  • 12 0
 First Blood Part II
  • 3 0
 @rockyjonny: what about the onestroke 4 ONE ?
  • 9 1
 Fourstroke One Part Two: Pneumatic Boogaloo
  • 2 0
 @chaoscacca: This is the best reply I've ever read.
  • 1 0
 Repeat fourstroke over and over and it makes less and less sense
  • 65 2
 THIS IS WHAT IVE BEEN LOOKING FOR
  • 306 0
 Mine auto drops when when I want to climb...Oh wait thats a reverb
  • 59 4
 OK COOL. WHY ARE WE SHOUTING?
  • 7 5
 @mininhi: LMAOOOOOOO
  • 6 8
 SAME. I've always felt that droppers were "backwards" with regards to what happens when you hit the remote. Though I understood the mechanical reasons.
  • 2 0
 ME TOO
  • 22 1
 LOUD NOISES!
  • 39 0
 @mab411: If they were only one direction but the opposite of how they are now how would you get your dropper back up? By clenching your saddle firmly between your cheeks and standing up?
  • 11 0
 @jmd07aa: Prehensile cheeks!
  • 7 0
 @jmd07aa: Wait this is what I've been doing the whole time. Its wrong??
  • 7 2
 Meh. I'd prefer the 120g weight savings, and have an infinitely adjustable, ass powered dropper.
  • 3 0
 @jmd07aa: yep and it is a super light and cheap system. You open the clamp and the saddle goes down by itself. You can then pull it up and close the clamp.
  • 1 0
 OOOH OOOHH AAHH AAAAH
  • 1 1
 @mininhi: as Sheldon would say: BADUM TISS!
  • 1 0
 @bigtim: kimura is EXCITED!
  • 1 0
 I'm glad you found IVE.......
  • 1 0
 OK, EVERYBODY HAPPY?
  • 2 0
 @jmd07aa: First off, I have VERY dexterous butt cheeks. Back in the day, I could tie shoes WITH a double knot, then do trigonometry on a TI-65. I had a whole show put together, helped pay for books in college. I'd be typing this with them right now if I weren't sitting in front of a classroom of 8th graders.

Second...I dunno, I'm just the idea man. But the fuzzy idea I had was something that provided pressure for it to stay up, probably with some kind of latch to keep it firm, then when you hit the lever the latch is released and whatever provides the pressure is isolated from the system, causing it to fall. (Edit: or some kind of motor.) But the smart folks at BMC have a much better plan. Wonder if they'll release an after-market version?
  • 50 1
 I'm holding out for the return of Shimano Airlines so I can integrate the air can into both my shifting and seatpost. That way if I drop my seat too often, I also won't be able to shift.
  • 22 0
 I'd only do this if the air is actuated by Bluetooth so I have to charge the sender and the receiver as well.
  • 3 0
 Then use whatever you have left at the end of the race for forward momentum in the sprint finish.
  • 5 0
 The battery on your ebike can run hydrogen generators to run a turbine to run a hydraulic pump to run a compressor to make it work.
  • 49 1
 Well, this is actual innovation... cough cough Cervelo
  • 8 11
 Naaah that's lame. It would be innovation if it had the dropper charging again and again thanks to regenerative braking.

(I'm kidding, I don't really care, but that would be neat though)
  • 3 9
flag pakleni (Oct 5, 2022 at 10:42) (Below Threshold)
 I'll admit that the bike is innovative with all the right angles and I'm sure it rides great, but it's not a beautiful bike like the previous generation. This rear triangle looks like it was borrowed from some other bike.
  • 6 0
 Seriously lol. I love Cervelo's road bikes as much as the next guy, even if they are a bit... erm, yeti-ish... But that hardtail is sorta sad. I'd rather them rebrand a SC. Won't stop people from buying it lol.
  • 4 0
 I came here to post the exact same thing. Take note cervelo, this is a what a good bike looks like.
  • 3 7
flag Will-narayan (Oct 5, 2022 at 16:09) (Below Threshold)
 @pakleni: It seems like BMC fanboys are here en masse, can't say a bad thing about this bike (even joking) without being neg propped.
  • 41 0
 my bike has as self-dropping chain
  • 1 0
 My irritable bowel Demands a self-dropping trou.
  • 25 0
 I'm impressed. Innovation for the race-bike, and conventional round seatpost for others. I like the commitment to a four-bar suspension over the trend towards flex stays these days, too. And best of all, without headset routing. Kudos BMC, Cervelo can learn a lot from them.
  • 4 5
 It's not a four bar though it's a Co rotating dual link like a dw link, the rear triangle is solid.
  • 5 0
 @AddisonEverett: I'm pretty sure this still counts as a four bar: 1) bottom link, 2) rear triangle, 3) top link, 4) shock. Just a different configuration than a Horst four bar with 1) chainstay, 2) seatstay, 3) top link, 4) shock.
  • 2 0
 @AddisonEverett: the rear triangle is a link, one of four, the ground link is the frame, and the co-rotators are the input and the rocker links, the shock is not a link but obviously is what limits the motion, so think of it as a dyad aka a sliding link.
  • 3 0
 Exactly my thoughts. Headangle nice, no shitty cable routing, VPP. Only comparable frames with 100mm are Unno, Mondraker, Ibis and Stoll, any1 knows more? I mean around 67 degree headangle and VPP.
  • 2 0
 Ghost Lector FS
  • 13 1
 I dont need a Cross Country bike, but if I did I would strongly consider a BMC. They make cool bikes, and for whatever reason I think the aluminum 2 stroke a really cool bike.
  • 1 0
 @froday buy my Aluminum two stroke it’s a sick build and I’m also in the Southeast
  • 13 1
 The elephant in the room is the excessive weight that the air tank adds, it’s not just the weight of the tank it’s the weight of the compressed air ie. 200 pounds per square inch is huge.
  • 18 0
 I can't tell if this is sarcasm or if you are just a hard core WW.
  • 5 0
 @Snowytrail: Having read an argument on a 4x4 forum about airing down the spare tire to save weight, I am not sure either.
  • 4 2
 The mass of the contents of the pressure vessel at 200 psi, whether air or nitrogen, is going to be less than 10 grams...
  • 1 0
 @boozed: "pressurized Vessel" That's funny to say.
  • 3 0
 @boozed: but my CO2 can says 16g
  • 2 0
 @fewnofrwgijn: That's because it doesn't contain air or nitrogen at 200 psi.
  • 2 0
 @boozed: that’s right, where the lightweight CARBON dioxide version?
  • 2 0
 why not just use Helium... that should negate any extra weight. Maybe use in the tires as well, then this bike would be like 8 lbs total with the tires trying to lift the bike like Helium balloons. RACE WEIGHT and easy to jump stuff too.
  • 13 0
 "Ass-powered seatpost" - never thought about it this way Wink
  • 9 1
 Completely rad. Would really be a positive improvement for keeping the flow and momentum going and for XC would really save energy.
  • 10 0
 Call me a traditionalist, but I prefer ass power
  • 5 0
 You are a traditionalist!
  • 1 0
 traditionalist for sure
  • 1 0
 Or your progressive..? Work dat ass!
  • 1 0
 So you don't like the idea of a "pressurized vessel"?
  • 2 0
 POWER BOTTOM!
  • 10 2
 An “Ass Powered” seatpost that works with compressed gas… I’ll pass.
  • 4 0
 reduce reuse recycle babyyyyyyyyy
  • 1 0
 @owl-X: reduce reuse ecyce
  • 7 0
 They should rename droppers now this automatic post is out. This is technically a dropper what we have been using is a lifter Smile
  • 6 0
 I knew it. You can see this post in action at the final world cup XC round. About an hour into the race you can see the post drop automatically.
  • 10 3
 So if it goes down at the push of a button, why didn't they press the button for the last image of the bike on a descent.
  • 1 0
 thank you
  • 7 0
 He's going to push it milliseconds before landing and squashing his junk on the seat, thus saving the day!
  • 8 0
 It's only 80mm, probably is down in that pic.
  • 4 0
 @MarcusBrody: like the danger of a no-hander, maybe you can stay in the air long enough to extend and drop it before you land
  • 3 0
 @owl-X: And in a few years, people will be cycling it multiple times in the air and freeride purists at Rampage will be complaining that Brendog was robbed by "Drop to Top" judging.
  • 1 0
 @MarcusBrody: bro he's cheating on the lever like using a spoon across the nintendo buttons on track and field cmon
  • 8 2
 ahem.... i believe you mean... "By "automatic", they mean it can extend" OR "drop at the push of a button"

highly unlikely that it does both at the same time.
  • 4 0
 hopefully thay can integrate this into a seatpost where the valve is somewhere on the top. then it could work with any bike. I would get one for sure. This is the type of mechanical integration that i would like to see. No apps, no batteries, no subscriptions, just a simple mechanical solution to a problem, that's so mtb
  • 9 2
 I bet $20 the next AXS reverb has this.
  • 4 0
 You'll need more than that to afford it though...
  • 6 1
 It'll be interesting to see how you diagnose/access any air leaks on the integrated air tank.
  • 30 0
 Some stans in there should seal up any leaks
  • 1 0
 @brapaholics: at 200psi? (Genuine question, not a criticism)
  • 10 0
 switchback249 (2 hours ago)
"It'll be interesting to see how you diagnose/access any air leaks on the integrated air tank."

Just a guess but BMC dealers will be supplied with a lap pool placed in the back alley. Toss the complete bike in and yell, "Okay Fourstroke, let's see you do the breaststroke!". Reminiscent of witch dunking in the 1700's, if it sinks you know it was fine.
  • 5 1
 Yes BMC! Now make that air bladder be able to re inflate tires when needed. On board compressor. Mabey even have the fork be able to pressurize the chamber too.
  • 1 0
 i like that. Any pressure buildup in the fork lowers re-routed to downtube tank...which powers your Airlines too
  • 1 0
 We could just have one big air tank and some kind of AI-controlled system that pumps air around to the different components as you need them.
  • 6 0
 Automatic for the people?
  • 3 0
 It'd be perfect for my Santa Cruz Driver 8.
  • 4 0
 @ReformedRoadie: this post right here is the one I love.
  • 2 0
 @tommyrod74: crazy how some people are acting like this is the end of the world as we know it.
  • 2 0
 @feldybikes: And I feel fine...
  • 6 0
 I don't need this, but it is pretty darn cool.
  • 6 2
 The seatpost idea is cool, but what I'm really excited about is the geometry. It's great to see XC bikes getting less sketchy.
  • 3 3
 Welcome to 2019?
  • 5 0
 @LeDuke: How many XC race bikes had a 66.5° HTA in 2019? Most trail bikes had steeper HTAs than that in 2019.

It's not like other companies aren't slacking out their XC bikes, but most seem scared to even go below 68°. There are still a few bikes being sold with HTAs of 69° or greater.
  • 1 0
 Xc Courses have become legit vs dirt crits.
  • 2 0
 @DaneL: my 2011 bmc four-stroke had a 68deg HA. On 26er wheels. They've never been shy of trying things.
  • 6 0
 Alongside my Rolex collection, this bike is gonna be perfect
  • 2 0
 What's wrong with Omega and Spark?
  • 2 0
 @pakleni: Living in the Geneva area, I am more a Rolex and BMC dude than Oméga and Bold cycle
  • 5 1
 I just want a seat post, that when its all the way up...it firms up my shock damper (configurable perhaps?). When its all the way down, everything is wide open.
  • 6 0
 I hope you are being ironic as BMC literally had this with their Trailsync technology on their trail bikes. It does not look like their current bikes use it now though.
  • 3 0
 @GTChE: I'm being both.

I don't care about the XC side of things but for these new school 150-160 bikes, its perfect. Suspension gets much better simply because no longer do companies have to really focus on climb capabilities (as much at least) because this simple dropper post/damper system firms it up automatically. We'd get sprite climbing 160 bikes that go Full-DH with the dropper simply down. In the day where everyone is stupidly using sensors and Ai, the simply human controlled system using a damn lever I'm already pressing is a no-brainer.
  • 2 5
 @Svinyard: I've never used the lockout on my 165mm travel enduro bike. Well designed bikes just don't need it.
  • 2 0
 I can't wait for this to come in longer options. I'm always checking tire pressure before each ride, so I don't mind at all checking my post pressure too. Plus, if it runs out of air it still works like like today's posts. I'll buy one to support this development.
  • 2 0
 They should design it so you can recharge your canister by sitting on it from full extension. Although you'd probably have to pull it up and/or do multiple cycles of that as if you were pumping it up with a floor pump...and the seals would be tricky...hmm
  • 2 0
 I think the way this works is to bleed off the pressure inside the post when you lower the post automatically.

Basically, it’s a normal post until you auto drop it, then it uses the compressed air to act like your body weight. When the post hits bottom, it releases the Autodrop air (small volume, high pressure) to atmosphere. I imagine the action or resistance of the drop is very light, and very fast return, and it locks at both top and bottom position.

Then the normal posts pressure pushes it back up.

If the post could act like a pump it would have a lot more resistance during Autodrop and likely require significantly more volume in the tank.
  • 1 0
 I like it. I mean, I don't race so not really needed for me right away, but I could see it becoming more universal. If the tank was larger (so low enough psi for a tire floor pump), it'd be only slightly more work to pressurize before a ride. I already have to check and usually top off tires, this is just another 30-60 seconds of pumping.
  • 4 0
 Maybe fill the canister with compressed helium to make the bike lighter too!
  • 1 0
 What He said
  • 3 0
 Finally after pointing this out to people for 3 years straight saying “it already exists for BMC’s racers”, it’s actually a real thing
  • 2 0
 I'm really amazed the AXS post didn't include an electric version of this. It just seems so obvious that it's exclusion is baffling. It also would have made the price tag a little more palatable.
  • 3 0
 There's no reason why this would be easier to implement on an AXS post vs. a cable-released post.
  • 2 0
 @FloImSchnee: I don't think it would be that hard actually. Sure, maybe if you retain the current architecture of a gas or coil spring it's not really any easier. But there are other ways to make a drive a tube up and down within another tube. Just off the top of my head I'm envisioning a high rpm motor driving a worm gear hooked up to a rack gear all stuffed inside the tubes. And that's just the first thing that comes to mind so there could definitely be a better solution. If they're going to have battery power, they should use it!
  • 1 0
 @freetors: It's definitely possible, the trick is always getting it into a package that's competitive on both price and weight. I'm pretty sure you would need a motor that's a decent bit more powerful than e.g. an electronic derailleur motor, which means you also need a bigger battery, and then you end up with a product that's a few hundred grams heavier AND a few hundred euro/dollars more than a normal ass-powered dropper. Would you be willing to pay €1k for a 1kg dropper with this functionality? There might be some people who would but i think it would be a very niche product.
  • 4 3
 Mixed feelings about this bike. Huge respect to BMC for genuine innovation on the dropper post. This follows the trend extreme cleverness and out-of-the-box thinking that started with the URS.

But, although this looks like a great dedicated World Cup race bike, I would be hesitant to buy, even as someone who almost exclusively rides race-y XC, because:

-80 mm drop is not enough for most users outside of a race situation, and many other XC bikes can now run 125 mm+ ultralight posts (e.g. the KS Lev Ci) that allow them to become virtual short-travel trail bikes that are very versatile.

-Despite moving the shock to the top tube, there's no second bottle cage in the triangle, which is a huge advantage of most XC bikes with this design (e.g. the Epic). One of my favorite things about the Epic is that I can leave my hydration pack at home for any ride under 3 hours.
  • 2 0
 The fourstroke with round seat post gets you covered for the dropper travel and all of them have two bottle cage possibility Wink
  • 1 0
 @mariano69id: yeah, but getting rid of the integrated dropper moots the most interesting feature of the bike.

As far as bottle cages - No mounts on the seat tube. Looks like I guess you could run two on the downtube? I've never seen that before and seems like it wouldn't work on small sizes.
  • 1 0
 Praise where praise is due: The geometry looks spot on. I love that the trend of progressive geometry FINALLY seems to have arrived in the XC world. With this BMC, the Scott Spark RC and a couple others there's now a really decent choice of new-school XC race bikes available.


Onto the negatives: Although I've got lots of respect for BMCs engineering efforts, I personally (as an avid hobby XC racer) don't really see any tangible advantage over a regular dropper post. And besides not really seing how this would benefit me, I would definitley not want to be locked into their fully proprietary integrated dropper post system. Especially since it can't be swapped with a regular dropper. Same reason why I would never buy a Specialized Epic or Trek Supercaliber.
  • 1 0
 Progressive geometry has definitely been increasingly the norm in XC bikes and it's awesome. But 66.5°, that's wild! That's slacker than a World Cup DH bike from when I started riding in the early 2000s.

I gotta wonder if they're overshooting the optimum at this point. My Epic has a 67.5° head tube and it doesn't feel like much of a liability in the twisties, but it definitely feels more ponderous than the 69.5° on my '18 Epic or the 71.75° on the '14 (that bike was TWITCHY). How far does it go?
  • 3 0
 I had no idea XC bikes were getting so expensive. I've been looking at the Spark, but those top out around $10k, this thing is $13,500??
  • 2 1
 I'm half-inclined to support the UCI passing a rule saying "no stored energy is allowed on race bikes". Of course, that would eliminate electronic shifting as well. But, it is a bit weird to have batteries and pressure vessels to store energy for shifter actuation, dropper actuation, and dropper movement. On the other hand, as a guy who has never had electronic shifting, it sure seems like the reduced maintenance might be worth a lot to me. So, a rule against electronic shifting may be bad for participation by weekend warriors in races.
  • 3 0
 No stored energy would be a really good rule and would do a lot to get costs under control and bring back the simple charm of the bicycle.

A lot of people love their electronic shifting, but IMO as an AXS owner, it's a quality-of-life net negative. The benefits are usually bullshit. Less maintenance? What? I spend 10x the thought and effort charging than I ever did on running a cable every 1-2 years. And then there's "faster shifts" which is nonsense, since shift speed is all about cassette rotational speed, not actuation.

Mechanical MTB groups were so, so good before electronic, and the fact XTR continues to compete on equal footing with the SRAM robo-groups absolutely proves this. I would trade my AXS group straight up for the mech equivalent if it wasn't for resale and logistics.
  • 1 0
 Shit, downvoted, meant to upvote. I agree...no stored energy on race bikes.
  • 1 0
 Its powered by pressurised air and runs out as you use it. >>>>> It won't be adopted into mainstream use. Simple as that. @BMC you have wasted your money on this one.

Which is a shame as a self dropping dropper is a great idea if done right. But this isn't the way. I haven't come up with any better alternatives, but BMC are gonna lose money with this one. Soz
  • 1 1
 This is also the same reason tubeless tires never became popular
  • 1 0
 Who remembers shimano airlines?
  • 1 0
 I came here wanting to hate on an "automatic" seat post that, I assumed, used electronics to decide when to drop and left impressed at what is a very elegant solution to a problem I didn't know I had. Now I want, no, _need_ an automatic seat post on all my bikes! I'm not even being sarcastic here.
Pneumatics are cooler than electronics in a steampunk kind of way. #shimanoairlines Who wants *beep* *zzzzzzzzzzzt* when you can have cool *pshhhhht* noises. Also you can recharge your pneumatics on a ride with the pump you carry in your pack.
  • 3 0
 How do you control a partial drop, say if I only need to lower the post about halfway?
  • 11 0
 its an 80mm drop seatpost, thats probably most trail/enduroist's definition of "halfway"
  • 3 0
 Should be like the Transfer SL type of posts, only two positions, no partial.
  • 3 0
 For a trail or enduro version it'd have to be possible to stop partway down. This version seems like it'd need a hyd carriage to hold rider weight in the up position. so theoretically it'd be possible to stop half way down, but it looks like this version is up or down only, which seems the norm for xc race posts.
  • 1 0
 The travel on this is short enough that I don't think that's necessary.
  • 3 0
 Just wait until Scott announces it's new "Quadloc" lever system and you'll be all set
  • 2 0
 Needs a tiny peristaltic pump at the non-drive bb/crank meet. The preload ring could be used as the 'fingers' to drive air through a tube wrapped around it.
  • 1 1
 It would suck to discover only after you're trying to lean your bike into a corner that the post was running on empty and the seat didn't go down when you thought it would. I was renting a Scott e-bike (long story) and because of their asinine linkage, the bike has a tendency to yank down on the dropper post cable and thus pull the release when you don't expect it. So I'd dropped my seat before a flat turn, started leaning the bike over, and then instantly washed out when the seat hit my leg. That sort of thing (your seat should be down but surprises you with being still up) could well happen if you have a long ride, you're a bit tired and focused on other things, and you don't notice that the seat is apparently no longer charged up enough to make it down on its own.
  • 4 0
 So wait, I have to pump up my frame now too?!
  • 3 0
 This would be nice on my ebike I sometimes get exhausted trying to move the manual seatpost
  • 1 0
 I wonder if things like these will get banned from races because it's employing external power ( admittedly small amounts).
In HPV races for example ice vests were banned for that reason...
  • 3 0
 Version 2.0: air canister is filled by rider's farts.
Wait, it would be still ass-powered
  • 1 1
 Genuinely curious - is the way this is implemented (weight aside) the way that XC racers want, with no intermediate position?

Seems that ideally you'd just want a post that alleviated your legs from the work of squatting but still gave you infinitely adjustable saddle position.
  • 3 0
 My favorite part of this story is the final image where dude is sending it over some roots. With the seat up.
  • 3 0
 Some people just like to use the A/C with the windows open
  • 2 0
 Ha total fail of photo placement.
  • 1 0
 Nice bike and nice geometry in the lt ,and the price of the frame with a fork and dropper bot a bad thing ,considering other brands that cost almost the same but only for the frame ,very nice BMC
  • 5 2
 no two bottles? in Socal with one bottle you survive 30 minutes!
  • 1 2
 Everyone around here is using a Camelbak anyway.
  • 1 0
 Correction! You can take two bottles in the down tube
  • 1 0
 @JSTootell: Not me. One bottle cage on an XC bike is a dealbreaker. I don't want to wear a backpack in 95° weather.
  • 1 0
 @nattyd: I do a lot of racing around here, and that's what I see. I don't wear a pack, I carry two bottles. But most everyone else is wearing a pack.

I will be curious to see if that is still true when I race around here tomorrow.
  • 1 0
 @JSTootell: Yeah, not surprising, since many/most XC bikes can’t carry two. But for me it’s a dealbreaker. A large reason why I’ve stuck with the Epic vs. the Spark (still only one on Small frames), Fourstroke, F-Podium, etc.
  • 1 0
 @nattyd: Intense Sniper can carry a second bottle on the downtube. I didn't like the Epic myself, but love the Sniper. I'm in between sizes and went small since it was on sale and overall like it.

Best guestimate, about ¼ of the top 20 riders this morning had a pack.
  • 9 10
 you gotta love how they use a photo of a dude descending awkwardly, all his weight behind the fully extended dropper, in an advertisement for an 'automatic' dropper, that's not actually automatic but doesn't require you to weight the seat because weighting the seating is somehow going to rob you of .0003 seconds. XC racing is oh-so-silly.
  • 2 1
 It's called XC simping. You pay thousand of dollars and massive amounts of effort to get a few less seconds (equivalent to a bottle of bath water). Really to only difference is that you're simping after something that isn't a person.
  • 7 1
 That dropper is dropped. It only has 80mm of extension. Also, that dude descending “awkwardly” is faster than anyone you’ve ever met.
  • 1 0
 Can I get one that will drop and raise automatically so I don't have to think about it? Like with a terrain sensor and AI or whatever
  • 2 0
 Better yet, pressurize to 400PSI and then free ride the bike to see how long it takes the frame to detonate, you go first.
  • 1 0
 I’m not going to buy this bike or a 170/170 enduro sled, but I’m glad they exist and are innovating
  • 1 0
 Wait. Can we use the air tank as a way to link the fork and shock together in some sort of anti-dive anti- squat suspension system?!!
  • 1 0
 If f1 teams were tasked...
  • 2 0
 I had been wishing to use frames as gas tanks for hybrid propulsion before in-frame storage became a thing.
  • 3 0
 The price of ONE and TWO just gave me four strokes
  • 3 0
 Ass, gas, or grass. No one rides for free.
  • 1 0
 With the extra drop and auto down functionality, 23lbs isn't that bad. Throw a custom set of wheels and some Extralight on there and get to 22 lbs.
  • 2 0
 So, this is like my RockShox Reverb except the BMC drops when you want it to and then comes back up.
  • 1 0
 Curious- say you use 100x, and now the pressure is 50psi, requiring ass-power to drop. How many more cycles will the dropper work? What happens at some critically low psi?
  • 2 1
 Would it really be so hard to post the weight of the bike with the air tank full vs empty?? I mean come on...
  • 1 0
 Shouldn't be that hard to make a version of this that's refinflated by pumping the saddle up and down.
  • 1 0
 Coming up, an app eith preset positions and memory in case someone else rides your bike...
  • 1 0
 AXS
  • 2 0
 my favorite mountain bike word, "integrated"
  • 2 0
 I'll get excited when it drops twice as far
  • 2 0
 BMC Fourstroke 01 LT LTD One Four Loko SuperStroke BMX Background Edition
  • 1 0
 Wait, no integrated in-frame in-air tank storage, nothing to see here... Can it double with a hose to fill a tire?
  • 2 0
 Why is the guy in last photo Not utilizing the dropper post?
  • 1 0
 I am picturing the music from dropper video- in a @brianpark timelapse 3D print video Wink
  • 1 0
 why not apply a solar panel on the saddle powering a battery -> small motor -> seatpost in both directions! ? /s
  • 1 0
 This could still be "ass powered", it just needs a port in the saddle to allow you to recharge the tank...
  • 1 0
 YOU MEAN FROM FARTING!
  • 1 0
 Their model lineup reads like the lyrics of In Cold Blood by alt-J.
youtu.be/rP0uuI80wuY
  • 1 0
 I hate to say it, but that tiny change might lead to faster time over the course of a long XC race.
  • 1 0
 Can I practice my double back flips into a lake with this bike and it won't sink?
  • 10 9
 Funny…my post goes up and down with the push of a button, too!
  • 1 0
 YOU MEAN YOUR WIENER!
  • 2 1
 If it's not able to read my mind, I'm not interested...
  • 1 0
 New name should be Drop It.
  • 1 0
 Some 'optimistic' weights there I reckon
  • 1 0
 Can it really be manual if you have to use your ass?
  • 1 0
 Sorry I can't come riding, I haven't pumped up my seat post : /
  • 1 0
 Power steering would also be a great improvement for my heavy ebike
  • 1 0
 I hope they trademark “ass-powered” haha. Awesome.
  • 1 0
 LOL. He said, “ass-powered”
  • 2 0
 Great innovation.
  • 1 0
 Disappointed you can't pump it back up using your arse
  • 1 0
 If they use helium it would make your bike lighter, plus improve stability
  • 1 0
 Ass powered...like me after chili dinner.
  • 1 0
 Like this seat post, I am also ass-powered.
  • 1 0
 Did Dick Pound create this seatpost?
  • 1 0
 Does it even has a sag like a reverb?
  • 1 0
 the last pic makes no sense at all ??
  • 1 0
 Ok, that’s pretty cool.would be super useful for panic drop situations.
  • 1 0
 Extra seconds for Tom ‘unofficial BMC athlete’ Pidcock.
  • 1 0
 Self dropper would be great across the board, not just for XC.
  • 1 0
 Man... that dropper is the shiz!
  • 1 1
 This should have been done years ago.
  • 3 0
 Trek filed a patent for an automatically dropping seatpost, using compressed air, in 2011 p.vitalmtb.com/uploads/1607/US20150151804A1.pdf
  • 1 0
 This is cool
  • 1 0
 Arse Power...........
  • 1 0
 want
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