Generic Bridgestone CroMo...
 

Hi Everyone,

I recently acquired a 1989/90 non-export, Japan-only frameset with a tubing sticker stating only, "Bridgestone/ Cro-Mo frame." According to B'Stone's catalog for that year, frame & fork are indeed full Cro-Mo, but offers no further details; I'm kinda curious to know what it was.

Earlier models of this particular frame were made with Ishiwata triple & quad-butted tubesets and, while the frame is reasonably light, I can't imagine it's tri-butted. That said, the interior of the ST seems to measure 26.8 & the outside measurement is about 28.6. Any insights? :foo:

I'd of 26.8 would indicate a nice tubeset. Sorry, can't give much on the model or ride characteristics. Can you post pics?

I will post pics at some point (I'll have to snap them first), but the model itself is pretty obscure; it's a TC-545 Travzone. It's not the Travzone seen in US catalogs (which is a very unique 700c folding design), but in fact the immediate successor to the famous AC-545 Atlantis 650b touring bike (that's the 'Atlantis Mk 1' to you Rivendell fans). It was made for only a single year before Bridgestone discontinued the entire series, so it's the last of a long line (Diamond/ Eurasia/ Atlantis), and differs from the Atlantis only by having slightly wider dropouts (130mm), and (I'm assuming) by not having the Atlantis's quad-butted tubeset. Otherwise it's exactly the same frame, right down to the Alex Singer lugs & vampire-red paint.

Edit: Here are a couple of pages from Bridgestone's 1989/'90 Japanese catalog to tide you over until I post some pics of this frame; enjoy! :)

A lucky acquisition then ! Might it be the same tube set as the export Atlantis model ? Why do you think not ?

Was there an export version of the Atlantis? If so, I wasn't aware of it.

As for the tubing, the Atlantis usually had a gold & white '4130' decal at the top of the ST & shaped sorta like a squashed hexagon, specifically stating tri or quad-butted tubing (depending on the year); this one has a sorta generic later-style tubing decal, a little black rectangle, near the bottom of the ST, similar to the ones I've seen on the MB-3/4/5/6. It seems too heavy to be tri-butted & way too light to be plain-gauge, so I'm wondering if it's maybe double-butted?

26.8mm ID is consistent with a Tange double butted seat tube. They were one of the few manufacturers that did not use a single butted seat tube (except for their #4 and Prestige sets) and the top butt always had a 26.8mm inner diameter, so the manufacturer only had to stock one seat post size, regardless of whether it was Tange #1,2, 3 or something like Tange 900, 1000 or Infinity. Even Plain gauge #5 was 26.8mm for the seat tube.

Having said that, Bridgestone did have a long time relationship with Ishiwata. That ID would be consistent with the seamed, quad butted EXO-H tubeset, which was available around this time. Of course that assumes we're talking actual tube inner diameter and not the seat post. Allowing for a 0.2mm clearance fit would open on the possibility for slightly lighter gauge EXO-M, in addition to honed or reamed EXO-H.

I would be removing the fork and checking the fork steerer for the manufacturer's logo. If it's Ishiwata, the tubing is almost certainly Ishiwata. f it says Tange, it may indicate a Tange tubeset but they were a very big supplier of off the shelf forks during this period.

I own a Kuwahara Hi-Pacer that dates back probably to 1986. It has its original Tange front fork but the frame is made of Ishiwata EXO-H quad-butted tubes. The stock seatpost is 27,0 however.

Thanks @T-Mar; I actually did that earlier, and it's a Bridgestone fork. It looks A LOT like the Ishiwata fork on my Toei, but it is stamped with B'Stone's 'B' logo and below that, the alphanumeric code, "L 1 E."

Edit: Thanks for putting me on the trail, guys; assuming that it might have an Ishiwata EX/ EXO tubeset, I dug around a little, found an old Ishiwata catalog online, and took a few more measurements.
The result? The dimensions all seem to be consistent with an EX tubeset; so, maybe it is tri-butted after all. :thumb: My XO-3 is made from tri-butted EXT and I love the way it feels on the road; I'm hopeful the Travzone will ride just as well once it's finished!

Thanks again, Everyone!