I've seen instances of the 2500 "Special" having that crankset, what shifters?

[MENTION=20650]T-Mar[/MENTION] , really appreciate all that information. As soon as I get picture privileges - will share.

Tubeset sticker on frame says: "G3445 seamless high-tensile throughout".
Back of the crankarms say 48-5.

I've recently purchased serial number K9AU3795 . I'm thinking USA market 1979 ? The bike is silver with a Sugino Mighty Competition 2 chainwheel crankset. The rear is a five speed. It has aluminum 27 x 1 1/4 ARAYA wheels. A sticker on the seat tube saysG3445 seamless hi tensil steel throughout. It has Suntour bar end shifters and Suntour Cyclone deraillers front and rear. Suzue hubs. Maeda Industries Perfect freewheel?Also the front fork has a sticker that says SKV. The model sticker is gone so I'm not sure what I have here. Any help would be appreciated. Thanks

Thxs! That crank code indicates May of Showa year 48 (i.e May 1973). That corroborates that your serial number uses the Japanese Imperial Calendar and that you have a frame manufactured in August 1973. That's in the grey area where it could be a 1973 or 1974 model. Also, the hi-tensile tubeset is consistent with a 2000 Special of the era.

Suntour Ratcheting Powerthumb Barcon Shifters

Just uploaded pics of the bike - can share any pics of other components if you wanna see them!

Frameset only
 

Unknown year "2400" limited

Pretty sure it's a 2400, because of the limited decal on top tube.

This has one of the bizarre 6 digit all numeric codes. With no components, it also makes it harder to date (unless cable stops have date info?) based on the typical Sekai serial number formula.

Got this for a 6 pack, but has some seat stay damage as pictured. Maybe it's repairable? *Shrug*

Thanks in advance for any assistance.https://cimg6.ibsrv.net/gimg/bikefor...b2dfb5b8ca.jpghttps://cimg5.ibsrv.net/gimg/bikefor...57764ac5d0.jpg
https://cimg0.ibsrv.net/gimg/bikefor...8c5e45e6cd.jpg
https://cimg1.ibsrv.net/gimg/bikefor...7e76c07523.jpg
https://cimg2.ibsrv.net/gimg/bikefor...7746f8f7d3.jpg
https://cimg3.ibsrv.net/gimg/bikefor...75b22203ea.jpg

Damage on seat stay, looks like someone did a Drew and over clamped something or other 🤔
https://cimg4.ibsrv.net/gimg/bikefor...e654353433.jpg

Serial #370271
https://cimg7.ibsrv.net/gimg/bikefor...ebf379b150.jpg

Picked up this '83 2700 this past summer. Looks to be mostly original, except for the high gearing (52/47 rings mated to a 13-18 6-spd FW). Serial Number Y3Dxxxx
https://cimg7.ibsrv.net/gimg/bikefor...53521e7774.jpg
https://cimg2.ibsrv.net/gimg/bikefor...f4cd6189f9.jpg
https://cimg3.ibsrv.net/gimg/bikefor...7c84610fa4.jpg
https://cimg5.ibsrv.net/gimg/bikefor...742da0f622.jpg
https://cimg9.ibsrv.net/gimg/bikefor...fdcf1b35d6.jpg
https://cimg1.ibsrv.net/gimg/bikefor...4b3b45bef9.jpg
https://cimg2.ibsrv.net/gimg/bikefor...0cd127527c.jpg

Decal style puts it pre-1984 when Norco designed the graphics. Based on other 2400, top tube cable tunnels would place it post 1981. So that leaves 1982-1983 and it's tempting to say the latter based on the lead character of the serial number. However, given that this is an atypical source, there is a remote possibility that the frame features may not chronologically with the prime source.

Thxs for the PM. It appears that there has been a more extensive drivetrain overhaul than just the gearing. OEM spec derailleurs were SunTour BL (Blue Line) and it does appear to have the BL shift levers to support this. The chainrings on the Sugino AT crankset are OEM and the only change is the removal of the 34T granny. The OEM freewheel was SunTour New Wiiner 5 speed (14-17-20-24-30T). FYI, the frameset is Champion #2 only in the main tubes. The fork is Tange Mangaloy and the stays are hi-tensile steel.

Very Helpful

Thanks, Tom! I had assumed the ARX derailleurs were factory because this is the second '83 2700 GT Deluxe I've had with them. Derailleur date codes on the example above were both YE, while the example below had YH and YE. Serial number for the one shown here was Y2Mxxxx. Would Blue Line have enough capacity to swing the drivetrain you noted? I can't verify with Velobase offline.
https://cimg3.ibsrv.net/gimg/bikefor...b9af00e0e9.jpg

Blue Line rear derailleurs came in narrow, medium and wide range versions. The latter had a 34T large cog capability and a 36T wrap capacity, which is more than enough to handle to the spec gearing.

ISO Sekai 4000
 

I have fond memories of my Sekai 4000 frame I bought back in 1975/76 and am looking for one. Anyone seen one FS?

ideally, 54cm or 56 cm.

Can anyone help me with this? I've got an un-named frame. The serial number is M0E21307 which I think makes it a Miki frame from 1980. It has been built into a single speed so there is virtually no original equipment left on it apart from the stem and seat tube. The seat tube is an SR Laprade marked Japan 26.4. The stem is also marker SR. The brake levers are Shimano. The chromed fork suggests a slightly higher end model. The fork steerer tube is marked Tange OD and has traces of gold or tan paint, a similar colour to the 2700 GTs I've seen.

From looking at the few pictures I can find, The only model I can find with identical lugs is a 1979 Sekai 2700. I know Miki made frames for a few brands so this might not be a Sekai at all, but I can't find anything else with the same fork crown and lug arrangement. I bought it in London, so maybe it's more likely to be a European brand but I've looked at the likes of Union Sakai and they tend to have a different fork crown with a sharp point in the middle instead of a smooth scoop.

So my questions are, is there any way to identify this firmly as a Sekai?

Does the seat tube dimension give any clue as to the tubeset?

Thanks guys.
https://cimg9.ibsrv.net/gimg/bikefor...c1ca51d55d.jpg

https://cimg4.ibsrv.net/gimg/bikefor...d7b53be8e5.jpg
https://cimg2.ibsrv.net/gimg/bikefor...9b6113af48.jpg
https://cimg3.ibsrv.net/gimg/bikefor...93c7ce3089.jpg

Need for Help!!
 

The serial number is M5G00004. Maybe it;s Sekai. The frame is similiart to Bigfoot or another MTB (Full Lugged) 26" with a fork crown. Is there anyone who wants to help me to identify my bike? Unfortunately, the admin doesn't allow me to upload photos. I'm a neubie.

Thank You very much.

Need help identifying the model
 

Newbie here!

I bought a used Sekai 2005-2006 in a garage sale for $20 that has served me well for at least 8 years. I lent it to a friend that really needed it for 2 years. It has been seating in my garage for the last 3 years, and I'm seriously thinking about a frame renovation. While I'm debating if the emotional value would be worth the cost, I wanted your help to identify it's model.

It's an all-black Sekai, 61' frame. And it still has a very smooth ride.

I still can identify the following original components:
Suntour VGT Luxe Rear Derailleur
SunTour Spirt Front Derailleur
Suntour Shifters on downtube
Suntour Perfect 6-speed Freewheel
Sugino Bottom Bracket
Sugino Crankset
SR stem
SR Road Champion Handlebars
SR seat post

Serial number: Y0G7752

The paint was in terrible shape when I bought it, and there were no decals left in it besides the front badge. According to this thread, it should be 1980 model built by Yamaguchi. I would appreciate any help you can give me in finding the model.

Yes, it's 1980 manufacture by Yamaguchi of Japan. I don't have 1980 specs but the only model still using the Spirt front derailleur in 1979 was the 500 Standard, so that would be my leading candidate.

Thanks, T-Mar! I've been looking at pictures and catalogs of Sekai, and mine looks more of a 2700 model. Because of its setup, I find it harder to be a 500. But, who knows!

Does it have stamped rear dropouts with no integral derailleur hanger, or forged ones with the hanger? Provision for dropout adjuster screws?

Hi, Hudson308, it has forged dropouts with the hanger, but no provision for dropout adjuster screws.

Well that would certainly point to one of their upper-middle models, at least. What diameter is the seat post?

It has a 1" seatpost diameter.

I think that's the diameter of the seat tube of the frame. Can you give the (exact) diameter of the post that inserts into the frame?

Sure! The seat tube outer diameter is 31.75mm, while the inner measurement of the tube is 25.4mm.

Here are some pics (wish the paint wasn't so badly damaged):


https://cimg1.ibsrv.net/gimg/bikefor...528f4ada4b.jpg
https://cimg2.ibsrv.net/gimg/bikefor...fda73adbd7.jpg
https://cimg3.ibsrv.net/gimg/bikefor...1ef2a8326d.jpg
https://cimg6.ibsrv.net/gimg/bikefor...9f269c49bc.jpg
https://cimg7.ibsrv.net/gimg/bikefor...4164ab6bf0.jpg
https://cimg9.ibsrv.net/gimg/bikefor...e7d6b0dc5d.jpg