Admit it, you want to know how it rides don’t you? Though a computer generated image, it brings some interesting thoughts on where bikes could be headed. There was a day when people shunned 29ers, and even went as far as coming out with a 69er thinking you could have your cake and eat it too. Since then bike geometry has changed as much as people’s mindset and nowadays 29er’s stand tall above all.

Check out some more pics and a close-up of that “geared steering” setup & their pretty interesting reason behind it…

39er vs 29er
photos c. of Pactrick Ng via behance.net

Billed as “Interpolate” from the Ridiculous XC Bike catalog, CG Artist & Designer Patrick Ng, the brainchild of this concept is no stranger to us at Bikerumor. He is also the one behind the infamous Roost Carbon bike with 188mm dropouts, 28 inch wheels, and a 53t cassette. However crazy Interpolate seems, the concept has some interesting bits.

Those 39er wheels are huge to say the least and wheelies would be non-existence with that bottom-bracket about two-stories below the axle height, (though with 39 inch wheels, you could probably “roll” about everything there is). It probably wouldn’t even turn on a dime… or would it?

39er steering

Though this cracks me up, I’d love to give this thing a go for a few weeks. The idea is to have the bike fit similar to that of a 29er. The Interpolate’s geared steering rig is interesting. It is designed to allow you to change out the cog for different steering ratios, so in theory you could “speed up” the steering if need be. If this had a “slider” mount for the steering, you could also have infinite stem adjustability.  It also sits the rider back enough to eliminate front wheel toe-lap. Though appearing to put the rider back too far, the contact patch of that 39inch front tire is likely more than enough for gobs of traction.

39er specs

Ridiculous XC Bike – Interpolate:

  • 39 inch wheels
  • Repositioned steering input/ouput to eliminate toe-wheel collision.
  • Pulley steering system; swap sprockets to speed up or alter steering characteristics. (Steering ratio in current build: 1.16)
  • Inbuilt steerer chain tensioner.
  • Riding position similar to contemporary 29er XC bikes.

Patrick’s Behance Page


  1. I don’t if the future can thwart simple math and geometry. Trail is trail; rake is rake; front- and rear-center can’t be “improved”; a seat tube angle can’t be “improved”; a steep head tube angle won’t suddenly be awesome for DH; unless it’s South Park in Canada, this is like saying that there must be a better shape than a circle for a wheel.

  2. Let’s get a bigger road wheel before this. 100% of all XL road frames are retarded farm gates with tiny wheels. One wheel size does not fit all. They do 650B, why bot 750c?

  3. At 6’5″, my XXL hardtail 29er STILL looks comically small for me. I will buy a 36er when they’re well supported, or perhaps as a SS/rigid version should I get some money to burn.

  4. Looks like loads of fun for off road touring adventures. I see plenty of space to tighten up the chainstay and front length, and do away with the chain driven steering. Ignore the cynics, without bikes like these we there will be no creativity or innovation in cycling.

  5. I like the idea but the geometry is all wrong. Slack seat tube angle? Really? It should be 76-78º which would allow the chainstays to be shorter (though obviously they’d still be super long). The front center of this bike is on par with the Geometron and Pole bikes though. The reach is tiny at 440mm or is this meant to be a S frame?. It should be 500mm. Would love to try it though if someone ever built one!

  6. 49er are actually awesome : http://images.google.fr/imgres?imgurl=http%3A%2F%2Fteamgurramarcus.files.wordpress.com%2F2013%2F10%2Fcropped-c2a9pierickjeannoutot-44.jpg&imgrefurl=http%3A%2F%2Fteamgurramarcus.com%2F&h=398&w=885&tbnid=kyLoRTMsml7TFM%3A&docid=ToRpcBJPphaSrM&ei=xY_FVsa3L8X5avfNsegI&tbm=isch&iact=rc&uact=3&dur=451&page=1&start=0&ndsp=27&ved=0ahUKEwiGrq7ogIHLAhXFvBoKHfdmDI0QrQMIQjAM

    By the way slack seat tube make sense to put some weight on the rear wheel in order to get grip in steep climb but the bottom bracket should be as close to the wheel as possible to keep effective seat angle in an acceptable zone and avoid the rider being ridiculously stretched. Handlebar height looks fixed which is not so good. Front chainring is ridiculously big for those wheels. Quite an exciting design but maybe 32′ would be enough for the tallest people while keeping things simple.

  7. Looks kinda cool to me and yeah, I’d want to ride it, bad.

    Seriously, line up a bunch of weird bikes, and have this one amongst that group. I guarantee most cyclists would go for that bike if they only had 30 minutes and had to choose one.

  8. Interesting steering concept with the changeable cog. I’ve long planned to have Waltworks 36r if/when I ever see the days of disposable income again. I for one support these endeavors and proofs of concept from minds that like to see what if. It’s no fun being around negative naysayers that poop on everything like so many of these commenters. I have to deal with people like you enough in my life.

  9. @PIT. Great comment. 750c for road xl and up makes some sense and road is an area that has not been legitimately explored for larger wheel size the way mountain has with 29er and plus and fat size (all of which I believe are excellent evolutions). Id love to try it.

    I guess for now we will live with the big trend f the last few years in road tire size, 25c (or even 28c) instead of 23c (or even 21c). It is nice but hardly revolutionary.

  10. Sadly, this site is available to the general public, and now I am tasked with finding all the necessary components to build this. I am having a hard time finding the 434mm spokes for the rear wheel build with King hub. Has anyone else found the Enve M39er rim as well?

  11. la taille des roues 29 et 27.5 n ont rien d extravagant , il s agit juste pour une fois d une dimension intelligente et internationale
    alors que là je n y vois aucun intérêt qu un effet de style pour l Evolution des vélos c est la transmission intégrée et light qui devrait voir le jour ! un genre de vitesse intégrée jetable à l image de nos cassettes et chaines !

  12. a piece of art,extremely intersting.For me,I see bike as a way to move.Dont forget that in poor country ,a bike is as much if not more important then a car .Imagine this bike with an electric motor?it become a super bike. Keep your 700cc to race,,27.5 or 29 to ride,but come on,you have to admit that this bike(or another nice 36er) deserve at least a recognition of potential in their intended field of interest.
    Take note that I have never ridden a 36 er…:(

    what do you think?

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