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Child's On-One Inbred - Now Finished!

GiraffotoGiraffoto Posts: 2,078
edited July 2015 in Your mountain bikes
This is a bike for my oldest boy, who's just turned seven. It's an ongoing project, so there will be updates, but here's the story so far:


We're building it together - I supply tools, advice, and the occasional bit of extra strength, and he does the assembling. It's going to be more of a hybrid than MTB, but I'm guessing he'll be riding it more towards the end of the year - there's a teeny bit of growing still to do. There's also a teeny bit of building still to do, too. So what is it?

The frame is a 14" On-One Inbred 26er with slot dropouts. It's small enough, it's tough enough, and depending on what he gets into, it could be the basis for a singlespeed, hybrid, jump bike or full-on MTB. The fork is On-One Cr-Mo rigid steel, because at his weight, suspension is just extra weight to carry.

The wheels are the bright red articles off my old Specialized Hardrock - tough enough and red enough for anyone - with Geax Gato 26x1.7 tyres chosen for their low weight and rolling resistance. Brake rotors are 140 rear and 160 front, the cassette is 9-speed 11-32 and the skewers are the very best Shimano Deores.

The stem is a 50mm Hussefelt from my spares drawers, the saddle a Charge Spoon which was on my previous road bike, and the seatpost had to be cut down to fit in that tiny seat tube. The handlebar is temporary, just to make it easier to move around while we're working on it.

Still to come:
    Transmission - gears, cranks and pedals
    The definitive handlebars and grips
    And of course, pumping up that front.
Specialized Roubaix Elite 2015
XM-057 rigid 29er


  • jt_intheukjt_intheuk Posts: 146
    That's going to be a neat little ride!
    Pics showing the frame would be good.
    I've got Soul.
  • GiraffotoGiraffoto Posts: 2,078
    The frame is wrapped up in the delivery foam to keep it safe during assembly. It'll be unveiled at the end!

    The next stage will be the crankset - this was a bit of a challenge because of the dearth of short (~150mm or so) cranksets of reasonable quality. Stronglight do an interesting range, but they're rather expensive. In the end, I found this online:


    The outer ring is a separate single ring, but the inner and middle are riveted together and I only wanted the middle. Fortunately, my spares box includes the full sized Suntour XCT triple set (with 175mm cranks) from the old Hardrock, and all the rings on that are separate. Even better, the middle is threaded so I didn't even need new crank bolts. So we now have a single 32T chainring on a pair of short cranks, ready to be fitted!
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • dirkpitt74dirkpitt74 Posts: 518
    Looks like a good build.

    Where did you find the cranks?

    I'm going down the THORN route for my lads build.
  • GiraffotoGiraffoto Posts: 2,078
    Where did you find the cranks?

    Amazon. Search for "152mm cranks" and you'll find a lot of options, but you have to watch out for the bolt patterns - some are riveted, some have two rivets/bolts on one arm, and only the XCT JR seems to tick all the boxes and come in at under £20. (although the P+P appears to have gone up hugely in the past few weeks)

    If all you want is a triple, the bolt pattern isn't so important - but I'd decided to go single, and it was a bit more complicated
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • GiraffotoGiraffoto Posts: 2,078
    That impressively short crankset is now fitted, and the chainline seems to be near perfect. Also brakes, the proper handlebar, and rear derailleur:


    This is with the saddle at its lowest possible height. It's still a bit big for him, but a couple of months should see to that! And there's plenty of growing room too:


    At 1.92m (6' 4") it's a little bit short in the top tube, and the saddles a little bit low - but I could ride it quite comfortably. A few more details:

    That crankset, available from Amazon and some of the German retailers:


    The handlebars had to be this height to get the steerer tube the right length - they might spend a year or two slightly lower. Note the carbon fibre spacer - there had to be some carbon on it somewhere.


    The front brake:

    . . . and the rest of the cockpit:

    Red, red and more red!

    So here's the specification:
    Frame and fork: 14" On-One Inbred with slot dropouts, rigid Cr-Mo fork
    Wheels: Off my Specialized Hardrock, bright red
    Tyres: Geax Gato 26x1.7
    Handlebar: Selcof 600mm flat bar
    Stem: Hussefelt
    Saddle: Charge Spoon
    Seatpost: On-One
    Brakes: Shimano Deore 596, 160mm front rotor and 140mm rear rotor
    Crankset: Suntour XCT Jr., 152mm cranks and 32T steel chainring
    Pedals: Wellgo
    Cassette: Shimano 11-32 9 speed
    Derailleur: Shimano SLX
    Gear lever: Shimano SLX

    When it's finished I'll take the protective foam off the frame!
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • Lewis ALewis A Posts: 767
    It'll get scratched immediately anyway!
    Cube Analog 2012 with various upgrades.
  • GiraffotoGiraffoto Posts: 2,078
    It'll get scratched immediately anyway!

    Don't forget covered in mud, chipped from bits of gravel chucked up by the tyres, worn out by sand and dust, and all other forms of abuse a child can dish out! But it will really annoy me if I scratch the paintwork while we're building it up.

    While I think about it, there's another sort of frame protection I'm thinking about - can you still get those foam pads that every BMX bike used to have wrapped around the top tube years ago? Anyone know?
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • The RookieThe Rookie Posts: 27,761
    You can get them on ebay last I looked.

    Personally I'd try and find some prettier discs than those (promax?) especially as the pads only give a partial sweep so the inner will get cruddy, Hayes come up quite light and are readily available.
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.9Kg
  • GiraffotoGiraffoto Posts: 2,078
    You can get them on ebay last I looked.

    Personally I'd try and find some prettier discs than those (promax?) especially as the pads only give a partial sweep so the inner will get cruddy, Hayes come up quite light and are readily available.

    The front disc only got a very brief outing as a rear on my current bike while I waited for a matching one to the front to come into stock - hence the very limited wear pattern. The pad should contact the disc all across the drilled area. I don't think they're Promax.
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
  • GiraffotoGiraffoto Posts: 2,078

    Well, the stem still needs to be lowered, but it's done, it's ready to ride, and it looks very red! Its final weight is about 10kg, that's just a guess from picking it up. Simplicity and a small frame keep it light!

    The cement mixer isn't part of the final spec.
    Specialized Roubaix Elite 2015
    XM-057 rigid 29er
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