My Rowdy Rosko Hardtail 29’r with XX1

In the world of custom hardtail mountain bikes, there exist a few key factors that determine shredability. The most important, at least in my opinion, being the head tube angle. Next, is the rear chainstay length and both of which, affect wheelbase and thus how flickable the bike is. I knew I wanted Seth Rosko to build it…

Follow the key measurements, or increments with a solid build kit and you’ve got a hardtail that can behave like a trail bike, under the right rider of course…

My Rowdy Rosko Hardtail 29'r with XX1

If the rear end is too long and the head tube too steep, it’ll be good for XC racing, but suck for tech, steep trails, which is what I enjoy riding here in Austin. My key measurements were a 69 head tube angle, with a 120mm fork and a 430mm rear end. But that’s only the beginning of the build specs.

My Rowdy Rosko Hardtail 29'r with XX1

SRAM’s XX1 drivetrain is my current go-to group but my love for SRAM doesn’t stop there. I’ve been riding the hell out of their Roam 60 wheels and couldn’t be happier. For suspension, I went with a Rock Shox 120mm PIKE fork, because, why the hell not? By adding a Reverb dropper, I can suck behind my seat tube and point the bike down just about everything. This bike is rowdy!

My Rowdy Rosko Hardtail 29'r with XX1

Chris King‘s special selection to meet the somewhat strange shape of the Solid BMX tapered head tube, along with a black King BB and ENVE bar / stem round this build out, topped off with Fizik’s Tundra M1 carbon saddle.

I’ve been riding this bike, as is for some time now and honestly, I was holding off on photographing it for a few reasons…

My Rowdy Rosko Hardtail 29'r with XX1

The road to this frame is a long one. I originally wanted it to be a bike packing rig primarily, so I requested three bottle cages. I’d then swap out the suspension for a Whiskey or ENVE rigid fork. Summer came and went, as did all my plans for a MTB bikepacking trip…

My Rowdy Rosko Hardtail 29'r with XX1

As with a lot of custom bikes, sometimes the builder gets busy with both life and his queue. I’ve known Seth Rosko for a long time and the last time I visited his shop, I was so stoked on his operations (and his 650b singlespeed MTB), that I gave him a deposit.

My idea: a hardtail with a short rear end, partnered with a slacker than usual head tube angle. We’d use True Temper’s Supertherm tubing, go with a dropper post, through axles and a agave blur paintjob. Dimensions were set, increments of angles discussed and off I went about my business. A full year passed and after hearing that he had to move his shop not once, but twice, I finally saw a frame on Seth’s Instagram.

My Rowdy Rosko Hardtail 29'r with XX1

Well, the bike showed up and after the initial build specs: Maxxis High Roller 2.3″ front and rear, we found that the rear end’s spec of 430mm was shorted to 420mm somehow, resulting in the max tire size of 2.0.


Human error applies to everything, including custom frames. Seth and I talked about it and he’s making me a replacement. Until then, I’m riding this frame. Initially, I didn’t want to mention this mistake, but it’s important for people to know that yes, framebuilders too are only human.

What makes them great builders and businessmen is their ability to rectify any mishaps. So far, I couldn’t be happier with this bike – aside from the rear tire size limitations. The fit is great and aside from the rear end being shorter than I had hoped, it actually shreds like a dirt jumper. Simply lock the rear and rock, down even the steepest sections… Hopefully, its replacement will shop up and I’ll be able to go bigger on the rear.

My Rowdy Rosko Hardtail 29'r with XX1

For now, it’s got one rowdy-ass posture! In the next few weeks, I’ll be doing reviews on the SRAM Roam 60 wheels, Pike fork and Reverb dropper. For now, enjoy the photos!

  • Paully D

    Love the simple classic look of a steel hardtail. That build spec is amazing!! Hope bikepacking happens for you.

  • Maxwell Merkle

    sweet bike! Though I’ll never understand why people want to spec running hydraulic lines through closed eyelits. How much fun does that make installing/servicing/replacing your post/brakes?

  • Tyler Morin

    Did you end up running the new SRAM Guide brakes? If so, how are they holding up?

    • Nicholas Schaub

      Looks like XTR to me

      • GioFio

        Yup, XTR.

    • I have the Guide brakes, but have yet to install them.

  • What’s custom about the pike – just that it’s reduced to 120mm?

  • D0rk

    Love the color. Love the spec. I want my El Mariachi to emulate your bike. Just need to bring the fork out to 120 and get me a dropper.

    • D0rk

      Also, any plans to make a batch of your decals in white? I need some that will show up on a black frame to go with my Radavist top cap!

  • AttackCowboy

    Do you have a plan for this frame once the replacement arrives if you don’t mind me asking?

    • Jean Baptiste

      selling it to me

  • Chris Valente

    Why yes, I would like to take that frame off your hands once your replacement arrives. How kind of you to offer!

  • GioFio

    Oh come on, you can EASILY fit a larger tire in the back! There’s at least another mm before you’re hitting the seat tube!

    • Ha! But then, mud and sand!

      • ethan

        Think of it as a scoring/etching process. BTW, get Seth to route that dropper post cable internally for the next iteration. -ethan

  • Brian Cottrell-Thompson

    I have the same idea about using my 29″ wheeled mtb as a tourer. But, I’m planning on doing a full front end and tire switch for road tours. Put some drop bars, a barcon and a rigid fork with some all-terrain tires and go where the bike takes me. Some day, I hope to be able to give one of these fine craftsmen you feature some of my money. This looks like a fun bike.

  • mywynne

    It’s dirty, it’s got some bumps and bruises… Yeah that’s what we like to see!

  • Stoked that Rosko sources Solid head tubes.

  • boomforeal

    sucks that the cs came in too short, awesome that he’s building you a replacement. i’ll be curious to hear how the difference impacts the ride, all else being equal. would you be willing to post a full geometry sheet?

  • Ham Sandwich

    well howdy fuckin doo.

  • Awesome bike John! Love the fact you went with a Pike, this will make this thing go anywhere. Any reason why you didnt go for a stealth dropper post seeing that the frame was custom made?

    • They’re kind of a PITA to travel with…

  • Peter

    Curious to hear John’s, and the peanut gallery’s, thoughts on BB height on a trail (not-race) type bike like this. BB height plays such a huge roll in how road/cx bikes behave, but I don’t feel it as much with mtbs. Thoughts? Anyone ridden mtb’s with significantly different BB heights?

    • boomforeal

      as with any bike, bb height is a huge determiner of how a mtb will ride and feel

      high is good for pedalling in very chunky terrain, but raises the centre of gravity and mass substantially because its the point at which the majority of the rider’s weight lands on the bike when out of the saddle, and makes the bike feel twitchy (some call this “flickable”)

      low will result in more pedal strikes unless you’re careful, but lowers the centre of mass and gravity and makes for a more stable and planted feel, especially for fast riding and cornering

      which one is right for you is a matter of personal preference, but also perspective. having ridden and reviewed a lot of bikes in varying terrain, my unequivocal preference is for a bb as low as feasible – i’ll happily alter my pedalling technique to deal with chunk, but would never want to compromise fun and stability on descents or at speed

      • Agreed… I don’t like a super heigh BB when I find my geo sheet, I’ll post it. I can only find an older one with a few numbers off…

      • Sean Curran

        Personally, I always liked really low BB’s. When I went from 26″ to 29″ I found a frame that kept it pretty close to what I was used to. But the effect is not the same. The bike feels a little un-responsive. I mean it corners amazing, but for a hard-tail, its way more stable than it needs to be for normal trails, or atleast the ones I ride. I still like the bike, but theres more to a frame than a couple of numbers, a good builder would have picked this up pretty easily.


    The tapered head tube is a nice touch. Not sure on those stays but to each his own. Great parts spec! Any front end lift with those short chain stays when climbing?

    • It’s not too bad and I find that I can use it to my advantage in tight situations.

  • Peperbek

    You are absolutely right regarding custom builders being such good businessmen that stand by their product. Recently I had two custom frames that had clearance issues at the chainstay. Not enough room for normal cranks. The feeling of devestation is therefor familiar. But the feeling of getting great service from the people who actually make their own product is so rewarding that I don’t mind waiting a bit more for that unique frame. To err is human, even for custom frame builders ;)

  • Trevor H

    Bike looks great, very much lustworthy. Been waiting to see full pictures of the build. I have been thinking about a bike similar to this for some time. I am actually really curious why a ceramic BB was chosen. Its an area that can see lots of dirt/contamination, and as such can shorten bearing life. Also, on a bike that may hit some jumps and some impacts, I have found ceramics to be brittle and not stand up well with that sort of use..

    • That was an error. I didn’t use a ceramic BB in this bike…

  • Eirik

    I’ll gladly take it off your hands and give it a nice life in the dark woods of Norway as a 650b/29’er Frankenbike.

    • You could probably put a 27.5 wheel in the back and a long travel (150mm 27.5) fork and wheel up front and run it as a 27.5 trail bike, similar to the Bad Otis or a Cromag bike. But the BB might get a little weird.

      • Eirik

        Sooooo… are you saying It’s mine?!

  • les_thar_gy

    OMG one of your best photo spreads.. (but most are great though!) GREAT bike.

  • floody

    On the next revision, why not chuck a kink in the seat tube starting around about where the indent in the bidon is, and run both a bigger tyre AND 420mm stays? Might impede your bidon mounting options though. Anyway, rad rig! I especially love the STRAIGHT FREAKING DOWNTUBE!

  • Guest

    Interesting to see everyone alude to the Bad Otis as the archetypal all mountain 27.5 hardtail when Engin did it way before. I guess it boils down to what’s hip and what’s within reach on social media.

    • I also noted Cromag – was just giving readers a point of reference with the Bad Otis. Also, I’ve followed and documented Drew’s work a lot and never saw a 150mm travel, dropper hard tail.
      Got a link?

      • EffOhEff
        • I don’t see even a mention of a long travel hardtail frame…

          • EffOhEff

            That’s 150mm. And Boomforeal knows what he’s talking about.

          • I never said he doesn’t or didn’t. I just don’t appreciate snarky / accusatory tones.

          • EffOhEff

            Meh, I think my matter of fact way of speaking comes across as negative. That being said, I dont think leaving negativity at the door always delivers the best message in terms of market influence and giving credit where credit is due. Failure to acknowledge negative aspects of things is misleading. Your mention of Seth Rosko’s humanity aligns with this sentiment. It’s okay for people to kinda be dicks! It propels discussion and product evolution. You’re very lucky in that your negative commenters seem to at least know what they’re talking about. Regardless, enjoy the bike, and enjoy the replacement even more. Sorry to disrupt the vibes.

          • Look, I’m not new to this kind of interaction. I just think people have an edge these days, probably from other venues / forums / sites, where being negative or as you say, matter of fact tone, gets picked up out of necessity.

            I always try to present things in a constructive light, just like I did with referring to Seth’s humanity. Look, I was pissed about the clearances, especially after waiting for a year for the frame, but if I voiced that, the comments would have gone south. Instead, I went about it in a diplomatic manner.

            The way I interact with people on the internet is the way I do in real life. If you go around balking at people, or being ‘matter of fact’, or negative, no one wants to hang around you, other than people of a similar mindset.

            All I’m trying to say is, I prefer to take that millisecond it takes to re-read comments and posts to make sure it’s encouraging discourse, not shit-talking. Not saying you’re shit-talking, but you definitely have a tone in your commentary. Perfect example: ” I guess it boils down to what’s hip and what’s within reach on social media.” <– that's your comment, not the "Guest" as Disqus says.

            I don't think it boils down to either… But that's just me. I used Breadwinner's Bad Otis as an example because I photographed it and people responded well to it. If Drew had asked me to photograph his 150mm travel bike, I would have as well.

            I'm just trying to show frame builders some love, I don't think it needs to be a competition, as you seem to be making it out to be. There are probably other builders doing "rowdy" hard tails, I simply named two off the top of my head "CroMag and Breadwinner"…

            Ya know?

          • Don’t trip on these dudes John.

          • EffOhEff

            “Guest” is what using a computer at work does, not hiding in the slightest. As for your response, I respect what you’re saying. It may seem hard to believe, but I value your site’s seperation from the likes of bikerumor, at least in terms of its commenters. I’m sorry I come off as such an asshole, really. My outspokenness stems from a particular problem I see in the industry, and it is occasionally perpetuated on your site. That being said, I should know better than to think I can solve that problem in the comments section. I appreciate you entertaining my comments despite their perceived agression. I didn’t mean to attack you by stating “what’s hip and what’s within reach on social media”. Certain builders are popular at certain times, and social media pays attention to them. You may have influence in both spectrums but I sincerely didn’t mean to attach it at all to you. It was merely an observation of a real world phenomenon.

            Look, I like what goes on here, I know it doesn’t seem like that always. I’ll keep my shit to a minimum. Once again, sorry to upset the positivity.

  • EffOhEff

    Interesting to see everyone alude to Breadwinner’s Bad Otis as the archetypal all mountain 27.5 hardtail when Engin did it way before. I guess it boils down to what’s hip and what’s within reach on social media.

    • mp

      Rowdy trail hardtails were long established prior to Breadwinner and the Bad Otis.

      • I think he’s being facetious.

        • ethan

          Needs emoticons

        • mp

          This internet stuff is hard :-) ;-) !!!?!???

  • vopop

    Garmin mount looks nice. Which one is that?

  • Neil Fenton

    Throw a 26″ on rear for fun?

  • Looks rad, Its along the lines of my own 29er that I built but with a straight seat tube.

    Looking forward to seeing how Mk2 comes out!

  • JDawk

    Look great! What are the ramifications of taking a scallop form the seat tube to allow a bit more clearance (think time trial frame), quicker than a whole new frame. I guess it would ruin the lovely cleans lines though, so screw that.

  • Milin Balsara

    i just came in here to say thanks for the good detailed photos. My Geekhouse Sconey 29’er has been getting a new lease on life since I moved to NorCal. I, too, have joined the Hardtail with a dropper ranks, but my OCD was unsure of how to mount the dropper lever or run the cabling. I wanted clean lines, and so I looked to these photographs of your setup to begin to dial the bike in. I went with Wolftooth for my setup front and rear, primarily because I needed the 42t bailout ring in order to get to my favorite sections to shred without having to go through the trails overpopulated by casual hikers and dog walkers.
    Anyway, thanks for the photos! The rear end of my bike, too, is more “XC” oriented, but it hasn’t held the rig back at all in doing what I want it to.
    Running the dropper cable from the top tube underneath the splitting of the seatstays really cleaned up the bike a lot. Looking forward to breaking in the Thomson 27.2 dropper!