Niche bikes and wheel sizes are all the talk these days and UK’s On-One is joining the conversation with a bit of a back pedal: 24″ wheels and a 12″ frame.  The Baby Fatty shares a lot with its big brother, the On-One Fatty, such as a 6061 T6 hand welded frame, Sram X5 components, and the same CNC hubs.  Otherwise, the Baby Fatty is uniquely designed with shortened geometry to match the 12″ frame size and 24″ wheels, a new unicrown fork, and 4.0″ wide tires.   The Baby Fatty is slated to appear in November and will retail for £800.


  1. If I had a Gringo Jr. running around I would buy this for him over a front or full sus model with double or triple cranks anyday.

    This could actually be a great starter MTB

  2. It’s about time someone did this. I’ve been calling for this for shorter riders (even though I’m not one) ever since I started considering a fatbike in 2009.

  3. slyfink….
    It’s for kids to have fun on.
    Give one to a kid and see how many milliseconds it takes them to work out what its for !!!!

  4. Seems like a good idea to me for everyone not just kids. A 4″ wide 24″ wheel will actually be closer to 28.5″ OD which is still a perfectly respectable OD but will be lighter and cheaper and give more options for geometry.


  5. This is getting ridiculous.

    The bicycle industry is always whining about the multitude of incompatible standards, yet they keep flinging crap like this at consumers, whose bike-shopping task is further complicated by the mumbling bicycle showroom teenager salesmen who think ISIS is a metal band from LA.

    Ironically, it’s these small startups that are to blame, since they need to differentiate to get noticed at Sea Otter and Interbike.

    “Let’s make a triangular wheel that turns into a clock when it’s pedaled past 5.3MPH,” or some other crap no one cares about.

    Some bored engineer in a garage thinks, “What’s between 26 and 29? Hmmm, I’m bored, so me add the two numbers together, divide by two–VOILA!–27.5! Let’s do it!”

    And down the rabbit hole we keep going…

  6. The multitude of industry standards really doesn’t bug me like it used to. For one thing, I’ve worked around it with motorcycles and automobiles for years. Do you know how many bolt patterns there are for auto wheels, before you even start talking about diameter, width, and offset?

    If you’ve got a bike part with standard X, you simply have to buy parts that are compatible with standard X. It’s actually pretty rare that your choices are limited. And even if they are limited, I personally find that while in theory I want tons of choice, in reality the two or 3 available parts are completely sufficient. (like the tires for this bike)

    Sure if you’re an economical (cheapskate) guy like me who does most of my shopping at the recycled bike parts store, then stuff can be hard to find that’s exactly what you want. But hop online and it’s no issue at all.

    It’s actually pretty awesome how interchangeable bicycle parts are, especially when you consider aftermarket companies that offer solutions to normally-incompatible parts. (jtek, speen, problem solvers, etc.)

  7. Yeah, wow Patrick…

    The “good ‘ol days” (for the myopic at least) when all that existed were 26″ tires, 68MM English threaded BB’s w/ tapered spindles and 1″ threaded headsets.

  8. I know 12″ frames are generally for kids but what size of a small adult would this fit ? I’m asking inseam and height.

  9. Has something changed in tire manufacturing that makes it easier to create new tire sizes? Are tire molds easier to make these days? I wonder about this because I remember hearing so many excuses at the beginning of the 29er era as to why there were so few tire choices. Now Surly has the Knard and even Walt of Waltworks (a one man company) was able to get his own 36er tire made.

  10. @ steven – this frame is probably a good fit for someone 5 ft tall or less and 26″ or less inseam. Many women, people in Asia and teenagers in this demographic.

  11. Angry much Patrik? Leave it up to somebody to get sad about a really cool, unique idea. The fun part of the bike industry is how much stuff is out there. These are the things that give engineers, marketing guys, sales people, and mechanics jobs (and some headaches) and create competition within the market to grow the pie. Standards exist for a reason of course, but that’s clearly not the point here. Have fun!

  12. Don’t understand why people are getting all upset. These pages are usually full of ultra complex carbon full sussers costing £4, 5, 6 grand and above. Then along come Fatbikes, Krampus, monster cross, baby fattys and all kinds of bikes that cannot even be made to cost more than an entry level full sussers even with oodles of carbon thrown at them. They also don’t need a team of F1 mechanics to maintain them and they are FUN.
    I’ll say it again FUN FUN FUN FUN FUN.
    My Pugsley is a hoot, rides all the lines I’ve never been able to ride in 20 years, never goes wrong even when I ride it in the SEA and cost me £1700.
    My cross bike is also a hoot to ride offroad (in a terrifying way mind you) and also doubles as a touring bike and commuter. £1500.
    I am currently selling my full sus cos I’ve not ridden it in over a year.

    The industry wants to sell us car priced bikes and the small guys like Surly, Salsa and on-one are shouting **gg** off at them.

    Come on all you grouches, sell your quiver, and instead buy a fat bike for youself, wife and kids.

  13. Hey Bike Rumor, you may want to edit your article to show the correct price. On-One website shows ~£800, not £999. 🙂 Great idea for a bike though!

  14. @ James S.

    Good question. I would figure that molds are indeed easier to manufacture, what with advances in cad/cam manufacturing.

    But maybe the biggest reason might be the ability to be more sure of selling enough tires to be worht it? I’m not sure if its’ the internet or advancements in forecasting or ?

    I could be totally wrong of course, but my understanding with previous efforts was the basic “not enough guaranteed demand to justify the risk of buying molds”.

  15. Man, if my folks had given me a bike like that for Christmas… wow. Parents don’t let your kids see this! That’s a bike that say fun like nothing I’ve sen for quite a while.

  16. I’ve said what I’ve needed to say. And that being said, I’d like to see how many of my naysayers buy this bike. All talk, no walk–post back on here with receipts.

    Yea, didn’t think so.

  17. I for one am glad to see stuff like this coming to market, kids will have great fun with the baby fat bike.
    As a kid I had a Raliegh chopper was heavy as hell quite slow to ride looked like nothing else around and I loved it to bits.
    To people like Patrik who prob thinks bicycle evolution stopped with bikes like the Dawes galaxy go look around the bike shops we have now.So much choice something for all tastes and growing bring it on if it puts
    bums on saddles and gets people riding it’s ok by me.

  18. These Fatties based on 24” wheels rims may be a good thing. They will probably end up with wheels O.D. ~ 28” compared to ~ 30” O.D. for those based on 26” wheels. The 26” wheel based ones (even XSmall) may be a bit hard to ride and handle for small poeple and these 24 inchers may be an option for them. Of cours it may affect the market development of the 26 inchers. Also, these 24 inchers will probably be lighter and shorter which will make them easier to handle in hard cornering situations. Let see how the market will respond to such an offer.

  19. The 24″ rim size w/ 4″ tires is about the same size as a 26″ mtb wheel/tire diameter. In my eyes, they’re are not as overpowering and gives a better symmetry to the bikes outline – but that’s just aesthetics. Overall, likely more nimble w/ less weight.

    On-one tech says stand-over height is 27.5″. So it offers more clearance when your feet sinks in sand or snow.

What do you think?