People, lend me your brains! (help ID a frame)

[one-eyed_jim]

Re: Re:

What get's me is '92 Explosifs where, relatively speaking, cheap frames (as are '93 Kiluea's)
A new Concept top tube, all the brazings would not be cheap in comparison to what it was worth at the time of doing it, as far as I know.
Also modifying it to use a roller for the front mech in a time when toppull mechs where readily available just seems daft.

Those are all fair points, but how else do we account for a fillet-brazed toptube on an otherwise TIG-welded frame?

I'm also not entirely convinced that the toptube is Tange Prestige Concept. To me the ovalisation looks more pronounced, and the width at the seat tube is greater than might be expected for a Tange tube.

Here's a picture from the eBay auction:

http://i.ebayimg.com/00/s/OTAwWDE2MDA=/ ... A/$_57.JPG

Top tube is ovalized horizontally at seat tube and vertically at headtube.

Downtube is ovalised vertically at headtube but feels round at the seat tube.

That suggests a difference in profile between the two tubes. Tange Prestige Concept was unusual in that the toptube and downtube were identical, and both were nearly round at the seat tube end. The toptube doesn't look fat enough to be MAX OR, but might be a standard Columbus MAX (road) tube.

"The MAX top tube is based on a 31.7mm tube and biaxially ovalized to 37.5 x 26mm with a .7/.4/.7mm butting profile. When installed on a frame, the 37.5mm axis followed the long axis of the head tube yet traverses the seat tube, meaning it is significantly wider than the seat tube."

To me, a fillet-brazed (Columbus) toptube on a TIG-welded (Tange) frame shouts frame repair.

 

[FluffyChicken]

Re:

No idea, I would say it could be anything it lacks the smooth bulge butting at the top of the seatube too, should be noticable from under the top tube junction.

I did think it look chunkier than the Concept, but sometime photo's look like that.
A MaxOR or OR tube is not only expensive, it is also something a local frame builder may have lying around as it's what custom builders like (especially back then). Just seems overly expensive for a repair job on an Explosif.

If it was MaxOR you would know as it is wider than the width of the seattube and is easy to spot, unless of course it's a longer tube cut down.

Concept Tubing would be ~30/34 front 27/30 back.

No disagreeing, just don't understand why
All good fun trying to work and identify these.

For the record Explosifs used concept form 90 to 92 then Kilauea from 93 to 95 iirc

 

[FluffyChicken]

Re:

Saying that I cannot see the bulge (a reinforcing bulge often) on these good pictures)
1992 Explosif frame
viewtopic.php?f=6&t=268698 maybe you need to be with the frame, it's hard to see on Kili frames to.

I assume Explosif comes from the two rackmounts thay may/may not have been added (why not removed?), which switched to teh side threads sometime in '92 model iirc ?

 

[one-eyed_jim]

Re: Re:

A MaxOR or OR tube is not only expensive, it is also something a local frame builder may have lying around as it's what custom builders like (especially back then). Just seems overly expensive for a repair job on an Explosif.

For a job like that, the material cost of the tube is a relatively small part of the bill. Most of the cost is labour. For the replacement of a tapered Tange tube, a bi-ovalized MAX toptube would be the best match readily available to a British framebuilder.

I assume Explosif comes from the two rackmounts thay may/may not have been added (why not removed?), which switched to the side threads sometime in '92 model iirc ?

A '91 stamped P2 fork suggests a '92 Kona frame. In '92 only the Explosif used tapered tubes. '93 frames used inset rack mounts.

The location of the cantilever bridge crammed up against the rack bosses points to either the bridge or the bosses as a later addition. There's no practical or aesthetic reason to group them so close together if fitted at the same time. There's no particular reason to fit bosses so high up on a frame that has none, and there's no particular reason to remove them from a frame on which they're already present. To me that suggests the cantilever bridge is the later addition, and that fits with the idea of a modified cable routing. If the framebuilder received no instructions concerning the rack mountings, he would have left them in place and worked around them, fitting the brake bridge as low as he could without fouling the bosses. Braze-ons were cheap - a few quid each in the mid nineties. It would have been cheaper to fit a front mech roller than to buy a new front mech.

So how do we square an expensive tube replacement with a cheapskate cable roller? Crash damage might have been covered by insurance. Other modifications might have been at the owner's expense.

 

[RickTheUncivil]

Great discussion guys, you really are thinking on this one!
Considering the kit on the frame it backs up the idea of perhaps some crash damage repair since there is not much original left!
For example, the DX v-brakes are an obvious addition, but the suspected later addition of the canti bridge suggests that the original kit was upgraded to cantis, then they were upgraded to Vs. To me that suggests that this was previously owned by a tinkerer. Riser bars and a colourful stem also say to me that the previous owner liked to change parts and upgrade - fair enough. To me this supports the approach of someone who would go to the bother of having a frame repaired, which it looks like we have here.
Other kit looks fairly original, or at least from original period (ish), noting the early-to-mid 90s XT drivetrain, mavic headset etc. I still cant explain the front mech roller tho. The front mech is a 735 so may or may not be a replacement/upgrade, but why intentionally upgrade to an inconvenient mech?

To get the final answers I will have to strip the frame to metal and look for myself. I'm not doing that right now, the paint finish is fine and most of the parts are good to go. What isnt good I can find spares in the bucket, so I will give the frame a good clean, put it all back together and put some miles on it. For now the definitive ID question will remain unanswered, but perhaps next summer (or the next) if I need a project I will strip the frame and see what I find.

Thanks all for your thoughts on this, truly enlightening!

 

[one-eyed_jim]

Great discussion guys, you really are thinking on this one!

You can always count on me for a bit of overthinking.

The front mech is a 735 so may or may not be a replacement/upgrade, but why intentionally upgrade to an inconvenient mech?

Shimano parts have two-letter date codes, so you could check the back of the cage. My guess is it's original.

http://www.classicrendezvous.com/Japan/ ... _codes.htm

For now the definitive ID question will remain unanswered, but perhaps next summer (or the next) if I need a project I will strip the frame and see what I find.

Do so. It's always nice to see an old mystery revisited. I'd be curious to know the dimensions of the ovalized toptube too. Got a Vernier caliper?

 

[RickTheUncivil]

Code on the front mech is PF, JUNE 1991 by that list, so original era at least, which still doesnt answer the queston is the roller original or an ad-on? It must be! My brain hurts.

I don't have a vernier caliper but I know a man who does. One day I will map the tubes in detail and see if that helps ID the tubes at least, maybe even the frame.

Stripping is the plan but not yet. I will try it out and see if its a keeper before i decide how to go with this one, so far I have stripped and cleaned so next week is the big rebuild (hopefully) so i can get some saddle time before winter.

Cheers

 

[FluffyChicken]

Re:

For the record I don't disagree with Jim, never have
Other than not knowing what the top tube is. Only because ive seen concept tube look like that in pictures as well
Also some 1992 Explosif frames also had the side rack mounts. I still belive it to be a reworked 1992 Explosif.
I still don't get why anyone would bother or any an insurance company wouldn't just write it off for another replacement frame given crash damage could propagate to the connecting tubes

 

[Rampage]

Any update on this?

 

[RickTheUncivil]

Nope.
Sold the frameset on a few months back as I moved my pottering around town duties into a newer explosif with bigger wheels. Not heard any update from the new owner with any more details they were able to work out.