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(This post was substanically edited/updated on 5/8/14.)

I have a bike frame of unknown lineage.

What is known:

  • The serial number under the bottom bracket is IS513786. This fits with the serial numbers for Japanese made Bianchis.
  • The frame has Shimano EF rear dropouts that are stamped with 'IJ'. That means they were made in October 1984.
  • Although I can't be sure that the fork is original, the steering tube has "Tange.5.I" and a 'J' and 'S' in a circle stamped on it. Also, the crown race was originally JIS sized.
  • I got the bare frame, not the complete bike, and the paint is not original.

The dropouts were made in late '84 and we now know that the last two digits of the serial number do not represent the year. (E.g., this '89 Japanese Bianchi has a serial number ending in 86.) So the frame is likely from a '84 or '85 Bianchi (since the dropouts were made late in '84).

FWIW, I've posted pictures below; I've made sure to point out things that could help identify the frame (braze-ons, lug style, etc.). I've tried to arrange the pictures with the most identifying characteristics first.

FWIW, Here is a similar looking, but not identical, 1986 Bianchi Brava. (That Bianchi has the chainstay cable stop on the underside, while my bike has the cable stop on top.)

(I posted this information on a couple bike forums a few years ago. If you want to see what people said, here are the links to the two threads on bikeforums.net and roadbikereview.com.)

The bottom of the bottom bracket, including the serial number. Also note that there is a chainstay bridge. Headtube

The front of the headtube front. Note that the lugs have points in the middle (unlike some other Japanese lugs from that era). Headtube front

The Shimano EF rear, drive-side dropout. Note that there are no eyelets. The date stamp is on the back side, so it is not shown. Drive side dropout

The top of the seat stay cap has a flat surface and has nothing written on it. (Some bikes, like high end Miyatas, have curved caps and/or the company name cast into the caps.) Seat cluster

The head tube has a pump peg. Back of headtube

EDIT: The whole frame: enter image description here

The side of the bottom bracket: bottom bracket side

The frame's downtube shifter mounts: Downtube shifter mounts

The seat stays have a chain hanger. Edit: it's hard to see, but the chainstay cable stop is on top of the chainstay -- not below it. Seat stays

The fork: Fork

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  • Most serial number conventions I've seen have the first numeric denoting age, so likely an 85. Don't know the make but at least you can narrow to companies that were working with Shimano at the time in Japan.
    – DWGKNZ
    Commented Mar 22, 2014 at 20:15
  • Can we also have a full frame picture?
    – Batman
    Commented Mar 22, 2014 at 20:24
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    This is an excellent "identify my bike" question IMO. Photos, and you've typed in the text you have to make the question more searchable. Thank you.
    – Móż
    Commented Mar 25, 2014 at 1:34
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    First, respect! For trying to identify this bike for at least four years forums.roadbikereview.com/retro-classic/name-frame-212595.html. I spent a while looking and, while the serial number points towards Bianchi, the pointy head tube lugs do not -- Bianchi, then and now, almost always had a clean head tube for the big Eduardo Bianchi logo. This site forums.roadbikereview.com/retro-classic/… lists Limited; Brava; and the Sport SX as the three Ishiwata (Japanese steel) frames of the 80s. Pictures of all three show no-point head tube lugs.
    – joseph_morris
    Commented May 1, 2014 at 22:26
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    Here's a 1989 Brava with an "IS" serial number (also ending in "86", interestingly). The photo is hard to see but I think might have pointy head lugs. Fork is uni instead of lugged though. bikeforums.net/classic-vintage/…
    – joseph_morris
    Commented May 9, 2014 at 2:59

3 Answers 3

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I have a KATAKURA SILK bike with serial number IS514477. Your serial number is very similar. Maybe your bike is a KATAKURA bike.

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    Nice find, welcome to the site! Do you have photos of your bike to edit into the answer? Could be useful as a comparison.
    – Criggie ♦
    Commented Feb 27, 2022 at 1:35
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I think i may have the answer to your question. I believe your bicycle is a Takara. This is currently my girlfriends bike, and i have attached some photos. The only things that do not match up are: 1) The front of the head-tube does does not have pointed lugs.

Bottom Bracket

Head Tube

Drive Side Dropout

Head Tube with Pump Peg

Bottom Bracket

Left Side shifter mount

Chain Hanger, and chain stay cable stop on top of chain stay

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  • Thanks for the pointer. However, it isn't conclusive since I believe that Takara is a brand, not a manufacturer. For example, some of Takara's bikes were made by Kawamura (according to wikipedia), and Kawamura may also have made bikes for Bianchi.
    – lnmaurer
    Commented Oct 6, 2014 at 15:31
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    Please tell me that rear wheel was out for the photos? The axle positioning looks particularly bad, I hope its not ridden like that.
    – Criggie ♦
    Commented Jan 2, 2017 at 20:27
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The format of the serial number is the same as certain models of Katakura Silk.

The Katakura Silk serial numbers tend to be stamped on the lower seat tube, non-drive side.

The lugs, seat stay caps, fork crown and dropouts match the Katakura Silk.

Some of the Katakuras were chrome finished, some were white, and possibly other colours.

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