Welcome to the forums. I believe that the "C" is an incomplete zero. F5076264 would make it July 1985 manufacture by Fairly of Taiwan, a known source for Diamond Back BMX models in the mid 1980s.

When you said, "There are no DT bosses, just the locator for the campagnolo clamp on DT shifters it has", I took it to mean that there were no bottle bosses, as they are typically located on the down tube. Tube and chain stay ends are rarely mitered if the BB shell has flat ended sockets. This socket style allows more contact area for brazing of non-mitred tubes and chainstays.

Sorry, I don't know the manufacturer who used this format. It could be Japanese but I'm not sure. There are probably dozens of 1980s Japanese manufacturers who aren't covered by the guide.

long time listener ! First time caller :)
 

Greetings from the antipodes !
Hope all is well your side of the world .

Bought a frame recently .
Original owner thought it may be a Shogun ?
HAs had a bit of a life . Painted over etc .
Anyhoo it has a serial number on the bottom of the seat tube ....
Also seems reasonable quality ?
has those slightly annoying Shimano lever bosses .
I have the same on my Koga Miyata Roadwinner
26.8mm seat post
126mm OLN rear
No top tube cable guides ( maybe removed ? )
Had forks with it that I dont believe are correct as they had no eyelets but rear do ?
Pics attached .
Any help with possible identity gratefully accepted .

Cheers
https://cimg0.ibsrv.net/gimg/bikefor...097fd5c402.jpg
https://cimg1.ibsrv.net/gimg/bikefor...2975af5cc7.jpg
https://cimg3.ibsrv.net/gimg/bikefor...3d8420e30f.jpg

https://cimg6.ibsrv.net/gimg/bikefor...61a44cc674.jpg
https://cimg7.ibsrv.net/gimg/bikefor...c93584157b.jpg
https://cimg8.ibsrv.net/gimg/bikefor...3f3d3a3632.jpg
https://cimg9.ibsrv.net/gimg/bikefor...887410086d.jpg
https://cimg1.ibsrv.net/gimg/bikefor...122f044f98.jpg
https://cimg3.ibsrv.net/gimg/bikefor...9563360f13.jpg
https://cimg4.ibsrv.net/gimg/bikefor...d8a87dd860.jpg

Based on the serial number's format, its location and the frame characteristics, my leading candidate would be 1985 manufacture by Pacific Cycles of Taiwan. In North America, they are known primarily as a contract manufacturer for brands such as Lotus, Mikado, Nashbar and Supergo. They also have an eponymous brand, though I don't know if it extends as far back as 1985. Unfortunately, I don't have any appreciation for what brands they may have been marketed under in New Zealand.

Thank you for that post! Very useful info!

Great work and thanks for sharing. I am amazed and dissappointed in general that Ishiwata as a tube / fork manufacturer did not publish / keep records of their out put. They supplied many builders of bikes, but the question remains : Q was it the builders who stamped the frames ? Guess so. Love to know who the builder was for Bianchi frames - Japan in the early eighties **********

Hugo - Australia

Two for the list.

Gary Fisher Wahoo
GY562042

Bridgestone CB-1
MOJ 86784

Thanks

Agree

Confusing serial number
 

Hi all masters and experts here. I just found this frame with a serial number consist of all numbers (no alphabet) and wondering what brand of bike is this? The serial number is 931xxxx50
here I also enclose the picture. I need the information about the brand so I can repaint and re-decal the bike. Some words and insight will be very much appreciated. Thank you very much
https://cimg8.ibsrv.net/gimg/bikefor...13e77ce843.jpg

Red specialized allez SE serial number N672657 made in japan decal is a 1985 correct? need a few more posts before I can post photos.

Ignore the forum rules. Photos will upload to a gallery album under your name. Currently, there's a photo of a dog and a piece of cycling artwork but no bicycle photos.

I see that you are from Jakarta. Consequently, your frame likely carried a brand name that is unfamilar to most members, who are located in the USA. The serial number could be reverse engineerred several ways. The two most likely are 1989 and 1993. If that is a pulley on the back bottom of the seat tube to redirect the front derailleur cable, then it was likely manufactured in 1989. However, if it requires a top pull front derailleur then it was likely manufactured in 1993. What is the 4th character in the serial number?

Hi T-Mar,

I have two Maruishi bikes to add to your list. The first is, I believe, a 1983 Maruishi Roadace RX7 with serial number CQ12430. It is cobalt blue with a baby blue head tube (see Photo below). This bike was purchase as just a frameset with the headseat and bottom bracket. I'm not sure who the manufacturer of the headset and bottom bracket are but once I remove them, I will edit this post. The tubing is Tange Cro-mo and the seat tube inner diameter is 26.4mm. The second (white and blue) is, I believe from your list, an 87 Maruishi RX7 (doesn't say "Roadace" like the older model). This one has the following serial number: GF76577. It came as a complete original build. Frame, forks, and Stays are made of Ishiwata EXO Cromo Quadruple Butted tubing. The steer tube is Ishiwata 7.E? Not sure what 7.E is but thats what is stamped on it.

Crank - Shimano Biopace 2x
Rear Mech - Shimano 105
Front Mech - Shimano 105
Downtube shifters - 105
Brake Calipers - Shimano 105
Brake Levers - Shimano SLX
Pedals - 105
Stem - Nitto
Bars - Nitto B115 420mm
Seat Post - Sakae Ringo Laprade
Wheels are Shimano 105 700c.

A third Maruishi Roadace RX7 frameset I purchased (late 70's or early 80's??) is shown below as well (gold and black Frameset). Serial number is - MCM8203. It's stamped on the bottom bracket unlike the other two.

Thnak-you for the contributions. This frame was built during weeks during weeks 33-34 of 1983 and is in the gray region of the 1983 calendar year where it could be either a 1983 or 1984 model. If the tubeset is Tange, then the decal points to the plain gauge #5 tubeset for the main tubes, with the stays and fork blades being a lower grade material, almost certainly hi-tensile steel.



Yes, this is a 1987 model, with the frame have been manufactured during weeks 11-12 of 1987 and the fork being from May 1987. The brakeset would be Shimano New 105 SLR, not SLX.



This frame is a Roadace 707. I'm not positive on how to interpret the serial number. However, based on the frame features and model name I can narrow it down to a relatively narrow time period of 1982-1983.

I really need to proof read what I type! :lol: Yes, the brake levers are Shimano SLR not SLX (SLX is mountain bike lever). For the third bike, I really have no idea why I wrote RX7 instead of 707. :o

[QUOTE=T-Mar;22429003]Thnak-you for the contributions. This frame was built during weeks during weeks 33-34 of 1983 and is in the gray region of the 1983 calendar year where it could be either a 1983 or 1984 model. If the tubeset is Tange, then the decal points to the plain gauge #5 tubeset for the main tubes, with the stays and fork blades being a lower grade material, almost certainly hi-tensile steel. [QUOTE]

You're welcome. I am curious about how you derived plain gauge #5 tubeset for the main tubes and lower grade material for the stays and fork blades? The Roadace RX7 was the top of the line for the Roadace series and my 87 model came with a much higher grade quadruple-butted chromoly tubing. The Roadace 707, from what I have researched, is the predecessor to the RX7 and the one I listed in my original post has Cromo Butted tubes. If the earlier version (Roadace 707) of the 83-84 RX7 has butted tubes and the later one (87 model) has butted tubes, wouldn't it dictate this one to has butted tubes as well and not plain gauge #5?

As for the other two frames, you are correct, the brakeset is Shimano New 105 SLR not SLX and the other is the Roadace 707 not RX7. That's what happens when you type something up after a long tiring day! :lol:

Just pulled the BB and headset apart, and you are correct. The stats are seamed tubing while the main triangle is seamless. I find it very strange that the quality of the steel in all three years of the top Roadace series 707 and RX7 have completely different steels. What confuses me is that they went from the 707 with Ishiwata CrMo 22 double butted tubes for the triangle, stays, and fork to Tange #5 plain gauge triangle and seamed stays and then back to a much nicer quality EXO CrMo Quadruple Butted tubing.

Do you have any idea why a manufacturer would be so drastic with the tubing types for basically the same bike over the various years?

Regarding the frame composition, it is quite easy to determine, once you know how to read a tubing decal. Marketers took advantage of the technicality of bicycle nomenclature to mislead the average consumer, without actually lying.

For instance, the decal of your earlier RX7 says "Cr. Mo. FRAMES TUBES". Technically the "frame" only refers to the main triangle and the only "tubes" on a bicycle are the top tube, down tube, seat tube and head tube. The chain stays, seat stays and fork baldes are not considered to be "tubes". Consequently, on the RX7, only the main tubes are CrMo, with the stays and fork blades being lesser grade material. Since "butted" isn't mentioned on the decal, the tubes are plain/straight gauge. You said it was Tange and the only plain gauge Tange CrMo tubeset at the time was #5.

Conversely if you look at the Roadace 707, I'd bet that the Ishiwata 022 decal states "CrMo DOUBLE BUTTED TUBES FORKS AND STAYS". Since "double butted tubes" is specifically mentioned, we know that the main triangle is double butted (though Ishiwata used a single butted seat seat tube, with the seat post supplying the reinforcement of a top butt). Since the "fork" and "stays" are mentioned, they are CrMo, though though they are not double butted. There were no butted stays and fork blades during this era.

The bottom line is that you have to look very closely at what is and is not stated on the decal.

You seem to be under the misconception that the RX7 was the direct replacement for the 707. This is incorrect. While the 707 was the top model in the line in the very early 1980s, the later RX7 was not the top model. The replacement for the 707 was the SP Professional. The RX7's position may have varied slightly from year to year, but I know that in 1985 it was 5th in the road line, if we don't consider the grand touring models.

The fact that your later RX7 has a quad butted frame, is an example of the increasing value offered through tenchnogical advancement. The EXO tubesets, were seamed, allowing Ishiwata to offer butted tubesets at a lower price than seamless butted tubesets. Initially, seamed tubesets were less reliable and therefore less desirable, but advancements in welded tubing increased reliabilty to the point where, by the 1980s, the advantage of seamless tubing was primarily theoretical.

thank you very much for your response and your insight. much appreciated. the complete serial number is 931012450

Thank-you. There is a possibility that your your serial number is format yymmxxxx, so it could befrom October 1993, which would be late enough in the calendar to make it a 1994 model.

Thanks T-Mar,

Lots of information to absorb and to learn!

For T-Mar: I picked up a 1986 Miyata 610 yesterday that needs a little bit of work. Mostly original - except tires (of course), the stem & brake levers. The serial number on the BB is NU60951 - which seem to decipher to 1985, 21st fortnight ... so between Oct 20- Nov 2 - for the 1986 model yr. Did I get that date decoding about right?

N is 1985 and U is the 21st fortnight, which covers weeks 41 to 42. However, the year rarely starts at the begining of a week and I don't know if Miyata considered the first week to be the first partial week or the first full week. I also don't know if they used Sunday as the first day of the week, or Monday, as it's the start of a work week. Regardless, taking all these permutations into account, your frame was serialized sometime during October 06 to October 27. That's late enough in the calendar year that it should be a 1986 model.

Thank you T-Mar! Once I hit the magical 10 posts, I'll put up a pic in it's current condition/configuration. It shouldn't take too many "vintage parts" to get it back to original specs ... "he says with hope in his soul".

This is a great guide. I've seen Koizumi mentioned in a Kuwahara context, but not DiamondBack. Koizumi produced frames, forks, bars and seat posts for DiamondBack from 1979 - 1984. The Diamond Back Koizumi serial numbers are in the format:

YM####⚾︎. Y = year (9 = 1970, 0 = 1980, M = month (but as letters A= Jan etc, B=Feb) the last 4 numbers are the unique identifier for the bike produced that month, so 0001 is the 1st, 0002 the second. The baseball type symbol is the Koizumi Kanji or logo. Hope that helps someone.