1996 Stevens 7.6.2. Comp (1991 Koga-Miyata Terraliner Carbolite)

[reindeer]

Thanks for the good news regarding cartridges @Elev12k

Some progress: The bars are described as “SR CMB 240 H 430 Tilver”. I reckon that means Sakae/Modolo Anatomic. Something Japanese would have been nice, but I’ve sourced these never used 25.4 mm Italmanubri instead
I never really liked the color of the Tricolor groupset, which is why I opted for BL-R400. Virtually the same, better looking (or less ugly) and even cheaper than used 6403

 

[Elev12k]

Will make a very nice bike. My current TerraLiner is not as high-end as yours, but at least I found one after nearly 30 years : https://www.retrobike.co.uk/threads/koga-miyata-terraliner-alloy.395405/

 

[reindeer]

That’s a lovely bike, @Elev12k. I remember me having a Koga catalogue when I was a kid in the early eighties and dreaming of having one.

Well, bad news! That strange Campa seat post...Hard to believe, but the former owner or his idiot mechanic has reamed the seat tube to fit a 26.2 post. Even worse, he did a bad job and reamed through the sidewall of the “carbolite” alu inner tube. It makes me wanna puke!

I rode it the week before and didn’t notice anything wrong. At the moment I’m undecided if I just ignore it or srap the frame.

 

[Woz]

25.8mm -> 26.2 post. 0..4mm in total. Each wall thinned by only 0.2mm.

Miyata typically overbuild, so I think it is still worth carrying on. Someone more knowledgeable may confirm that the AL
is just there for something to wrap the carbon around? I can't imagine the AL would be too structural based on those thicknesses. .

 

[john]

Nice frame, bad luck on the seat tube

 

[Elev12k]

For as far I know the inner tube is 0,7mm and is indeed for wrapping the carbon around. Pity he went through it, but if it works it works. If enough post is inside the frame and not outside and the frame is used on road it will be fine. If you're heavy and want to hammer it offroad this is not the frame for you anyway.

 

[reindeer]

I’ve tried to translate what is written about carbolite in their ‘89 dutch catalogue:

“Unique to Koga-Miyata Carbolite frames, is the usage of 0.7 mm alu tubes on the inside, that guarantee a lasting bond to the lugs, which is otherwise the weak point of carbon frames.”

Makes sense, if it was of no use, you’d just knock it out after wrapping. But it says nothing about the structural behavior.

In theory, it are only 0.2 mm on each side, yes. In fact there are 0.7 mm missing, where he reamed off-center and the tube just crumbled.

The QR also wasn’t original spec and slightly damaged the stays.

Maybe the seat post slipped with the original bolt. I've tried a Stronglight bolt which fits. Will it work in the long run? Anyway, too much botchery, I don’t want to think about any longer.
If somebody should be interested in the frame, leave me a message.

 

[Elev12k]

Marketing talk.

 

[Woz]

Have some faith in the Japanese engineering. Having had a Miyata MTB with bonded tubes, and butchering the bottom bracket to convert it to 68mm from 73mm I can honestly say they did know what they were doing with plenty of wiggle room.

To be blunt, build it, ride it like you stole it. You have nothing to loose. If it fails at that point, it will be a gentle failure (unlike say the downtube undoing from the headtube lugs) and you will be able to ride home with a safety margin. The rear stays will keep the diamond shape all in place.

As a final point. There is no way you could tighten a front mech properly if it relied on the AL wall thickness.

EDIT: You can't "knock it out" after. It's bonded with an epoxy glue layer after layer, but it needed a form to start with. Carbon fabric is floppy like a tea towel without form and epoxy glue.

 

[reindeer]

Thread resurrection: Another promising victim for a gravel conversion has reached my home

Stevens “7.6.2. Comp”. Exact year: Unknown, as they aren’t well documented. Also no numbers on the frame or forks indicating a date. But guess something around 95. It’s just a make of a german wholesaler from Hamburg, but I remember thinking of them as being cool bitd and I like the lettering


Maybe it’s a short story again: The bike was standing in the backyard (total mess), when I picked it up. Telling from the matte paint for a looong time. It even surprised me that the seatpost wasn’t stuck. The headset was baked to the forks and hardly moving even with the help of a hammer

Maybe I’ve destroyed the lower needle bearing by tapping it off, no idea where these two metal fragments belong to. Frame needs further inspection regarding rust, but after some polishing the paint looks acceptable again