panzerwagon 

Does anyone know where to get some lengths of Ishiwata 022E Croston "Quatro CRMO" butted tubes used on some old Bridgestone bikes? Is there a modern equivalent that''s still being manufactured?

unterhausen

My recommendation is to settle for any modern tube that fits. Ishiwata is gone, but kaisei is a direct descendant. You probably can't get a direct replacement for a tube like that, but the likelihood that you can tell the difference between those tubes and a modern tube in a completed bike is small.

panzerwagon 

Thanks for your reply.
Within the Kaisei line, which tubing would you think comes closest to the quality of the quad-butted tubes?
And do you have any recommendations for sourcing these tubes?

unterhausen

022 was .9/.6/.9, so just about any 4130 tube in those dimensions would be very similar. I don't know what the quadro refers to, some marketing silliness, I suppose. I don't know if Kaisei tubes in those dimensions are easily available, but the Nova road tube set is probably very similar ROAD TUBESET 9/6/9 TT AND 9/6/9 DT :: ROAD TUBESETS :: NOVA :: STEEL TUBESETS :: TUBE SETS :: Nova Cycles Supply Inc.

Andrew R Stewart 

Compass Bikes lists Kaisei tubes, here's a link.https://www.compasscycle.com/product...framebuilding/ Like Eric I suspect "Quadro" is a marketing term. Back in the late 1970s and early 1980s Fuji used a quad butted tube set (or claimed at least one tube was butted 4 times). The lack of market demand was the likely reason that this quad butted tube(s) was moved on from. Columbus has produced tubes with differing butts along the lengths and around the circumference for a while. Again the lack of customer demand likely was small so...

Eric makes good points about the "quality" of tubes of the same material (4130) being about the same. While there have been tube material mistakes the usual booboos are dimension control ones. The butt isn't where it is meant to be, the tube is out of round or is bowed more then usual. Or something got caught in the drawing dies/on the interior mandrel resulting in a local "scar". All of these common issues are visible and/or measurable.

I have no concerns subbing one brand for another when the tube material and dimensions are the same. The few Nova tubes I've used cut, file, braze up the same as other "name brand" ones. Andy

unterhausen

We don't know what this is for, so it's hard to comment on the suitability. Since the heyday of Ishiwata, 9/6/9 has become tubing dimensions for a bike that's going to see heavy loads or for large bikes. I only rode a 022 Trek for less than 50 miles, but I wasn't impressed, I thought it felt dead. 019 is where it's at. I am pretty sure my current road bike is 8/5/8 Reynolds 531 and I like that a lot.

The magic of a particular bike is generally related to the geometry. So the same geometry as the Bridgestone in something superior like modern Columbus SL or the Kaisei standard diameter tubes will probably make a more responsive bike.

panzerwagon 

unterhausen

since you can't get the original tube, I wouldn't overthink it. If you are going with an established builder, just ask them to use their best judgement.

duanedr 

A couple other approaches might be:
1 - Call Grant at Rivendell and see what he says. He designed the bike as I understand.
2 - Cut out the original tube as close to the lugs as practical. Once you have the tube out, cut in half along the length to see what the butting profile of the original tube is and match as best you can from there.

There are many nice lightweight tubes on the market now including the Kaisei line as well as others. My guess is that a suitable replacement is readily available.

unterhausen

I saw this interesting link today. They have 2 Ishiwata catalogs The Bicycle Info Project: Technical manuals home page

pwyg

I have NOS Ishiwata tubes and tube sets. My personal view on quad butted tubs is the manufacturer was counting the transitions as butts. There is no real gain stepping a tube that much especially with the over all length of a tube. The weight savings of a double butted tube is minimal compared to straight one but the drive for light frames makes every gram count. Thinner in the middle simply correlates to the tube twisting more and a bit of compliance. And some of can still vary depending on the condition or heat treatment of the tube. To my knowledge Ishiwata tube were raw un treated 4130 but I would have to put a file to one to determine that.