Japanese bike and road bike frames.

Discussion in 'Cycling Equipment' started by manuelgabriel, Jun 7, 2012.

  1. manuelgabriel

    manuelgabriel New Member

    Jun 7, 2012
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    Is it possible to switch a frame of a japanese bike and replace it with a frame of a road bike? I would like to make my japanese bike a road bike. Is it possible that I could replace the frame? This is the picture of my japanese bike And this is my desired road bike frame Please help.

  2. dabac

    dabac Well-Known Member

    Sep 16, 2003
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    With bikes, just about anything is possible.

    Whether it's sensible or not is another question.

    The bike you have appears to be internally geared, can't judge the wheel size. Rims/tires appear fairly wide. Looks like it'd be a square-taper BB.

    If wheel diameter is off, you may not be able to make the rim brakes reach, even if you're ready to replace them with other versions.

    If wheel diameter is correct, a modern road frame may still not be able to take rims/tires as wide as you have. And there's a limit to how narrow tires one can safely run on any given rim.

    Fitting an IGH to a road bike often leads to trouble with dropout spacing. Any reasonable modern road bike will have 130 mm rear dropout spacing. An IGH(internally geared hub) intended for an IGH frame is usually narrower. There are IGHs that can go in road bike frames, but they're built fro that from the start. Replacing an axle in an IGH is doable, but the added cost will quickly cast a financial shadow over the project.
    If it's a steel frame, it can usually be respaced and have the dropouts realigned. That can be a fairly scary manouver, and require some skills.

    In reality, there isn't much of your currrent bike that would be transferable to a "road bike". Wheels, bottom bracket, cranks, saddle, seat post, stem - and they're all "maybe"s.

    The frame you've posted makes me wonder too. There's a wicked difference in angle between the head tube and the seat tube. I think it's an old cruiser frame and not an old road frame.

    So, there's a bit of guesswork here, as there are plenty of details needed for a thorough answer missing:
    - your donor bike, a "townie" of unknown but probably mid-range quality, isn't a good candidate. There aren't any parts that can be said right off to fit in a random "road bike" frame. Well, maybe the saddle, but it looks kinda wide for the kind of riding I'd expect from a road bike.
    - your intended receiver frame probably isn't a road bike frame.
    - By the time you've bought the parts that are flat out missing(headset, stem, bar, brake(s) levers...) and replaced the parts that didn't fit, you'd have payed a lot more than if you simply bought a used road bike in the first place. And if my guess about the frame is right, you'd still end up with a mongrel bike.
    Unless you have endless access to bike parts or don't care about the cost, don't try.

    Oh, that your donor bike is "japanese" isn't particularly important in this case. That you want to use a "townie" as a donor bike for a road bike build is the important info.
  3. alfeng

    alfeng Well-Known Member

    Jul 23, 2005
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    Which parts are you hoping to transfer?

    By my reckoning, the angle of the chainstays suggest that the "Japanese" bike has 26" wheels ...

    While you could mount the 26" wheels in a 700c Road frame, the resultant Bottom Bracket height would be REALLY LOW to the ground & the possibility of the pedals hitting the pavement will be greater in situations when the bike is less than vertical ...

    • a BMX brake caliper might have the REACH to allow you to use 26" wheels in a 700c frame ... no guarantees!
      you COULD have 700c rims laced to the hubs ... that probably won't be cost effective unless you can DIY, and even then the cost might not be reasonable.

    As dabac has noted, few of the other components (other than the rear rack) can be readily used on another type of bike.

    In the end, unless you are living in a remote part of the World where parts & frames are few-and-far-between, then you will probably be better off outfitting any Road frame you acquire with different components.