TugaDude

Found this when looking over Columbus tubesets. Interesting, if accurate, it explains a lot.

"This tubeset, Chromor/Thron has a long history that includes Touring frames for Schwinn in the 80's and 90's with Prelude and Tempo models. Schwinn manufactured approximately 25,000 of these frames during this time using the name Tenax. We sold Chromor and later Thron as Columbus entry level pro tubes just below SL/SP. The Thron was also sold by Nova as a successful MTB tubeset with MTB chainstays as an entry level pro set."

Scooper

Nova misspelled Cromor (there's no "h")...

oddjob2

You could add to that entry in Wiki fashion and say:

"It is believed that Bikeforum.net members collectively own 1/2 of the still surviving Schwinn Tenax road bikes in the free world."

The Golden Boy 

Truth.

RobbieTunes

I always wondered about Thron. I've seen it on classic bikes, but a fairly modern Univega I had, with Thron, was definitely OS and definitely heavier than any of my C&V frames.

TugaDude

Now THAT is funny! And undoubtedly true. Sold an '85 Letour Luxe I still wish I hadn't.

zazenzach

Rez'ing a zombie thread....

Scooper, I measured my TT, ST and DT with a caliper and they fit those Cromor dimensions precisely.

when researching tenax there is an abundance of contradictory information, so I'd like to put the final nail in the coffin on this once and for all. The only issue preventing me from declaring tenax as early cromor, is that Schwinn's own catalogues claim tenax to be double butted seamless tubesets- which contradicts it with being Cromor (as it is seamed).

Do you know how SL/SP measurements would differ, as some have suggested tenax is just a rebranded mixture of both?

Edit- i suppose I could pull out the BB and look for seams from the inside, but id rather save myself the hassle.

zazenzach

well looks like i commented too soon. i ended up tracking down your comment here: https://www.bikeforums.net/showthread...-of-1987/page2

it seems like we may never really know what exactly tenax was.

Scooper

We do now.

Between the description of Tenax as Cromor on the Nova website and this definitive reply from Columbus, it's pretty clear "Tenax" is 25 CrMo 4 seamed, double-butted chromoly similar to Cromor for the three main frame tubes. Because of the 26.6mm seatposts used on Tenax frames, it's also a pretty good guess that the seat tube is straight gauge with 0.9mm walls.

RaleighSport

This should be a fun one to follow.. but how does the Columbus answer about it being seamed jive with the Schwinn claim of it not being seamed? Even more interesting is the measurements Zaz resulted with. Another thing I've heard in passing is Tenax actually improved over the years, I can't verify the veracity of that of course.. but it would be most interesting to get tubing measurements from the first Tenax bikes and then all the way up to the 89's which is where I believe it stopped?

Scooper

By the mid-eighties, welded seams were so homogeneous after cold drawing and butting that the tubes were, for all intents and purposes, identical to seamless. I think Schwinn took a little poetic license.

From the catalog specs, it does appear that Tenax was last used on the 1989 models.

RaleighSport

I just want to see a little more confirmation before I move my personal opinion to Tenax being Cromor SL/SP is just so much classier...

Scooper

As far as I can tell, all of the assertions that Tenax was really SL/SP originated with the Bicycling article on the then-new '87 Prelude.

I even bought into it for a while.

RaleighSport

LoL did you know you and I have discussed Tenax way more than once now? I was doing some digging since this one always fascinates me, and in my Premis thread I found a post of yours mentioning:

The 88 catalog refers to Tenax as seamless, For 88 Tempo, Premis and Prelude are all listed as seamless and double butted.

Now I took the liberty of course of checking 87, double butted chrome-moly no mention of seamless.

So I decided it might be worth hunting through the trfindley scans database a bit more:

86: We have the Tempo, Madison, Super Sport, Prelude. Double butted, no seamless mention. 26.6 seatposts.

For 85: Tenax models were Super Sport, Competition, Voyageur, Le Tour Luxe,Super Le Tour, Voyageur, Passage. Double butted, no mention of seamless and the universal 26.6 seatpost.

No sign of Tenax in the 84 lightweights catalog scans.

So now going the other direction things stay interesting..

89: Tenax models: Tempo, Prelude, Voyageur. Double butted and seamless again. Also very interesting, the seat posts evolved to 27.2 for this year.

Now if I had been smart I would have also been noting the bike weights.. but it does seem that Tenax did evolve.. perhaps it began life as Cromor twin and slowly became similar to SL/SP?

It'd be really fun to get some bare frame weights on same sized same geometry tenax bikes from 85-89 and do some comparisons there.

Scooper

Well, actually, while the specs list the 1989 Tempo as having "Columbus Tenax SL Seamless Chrome-Moly Double-Butted Main Tubes" and an "SR CRE-100 27.2mm Alloy Micro-Adjusting" seatpost, both the Prelude and the Voyageur have Tenax tubing (without mentioning "SL") and 26.6mm seatposts. The "SL" in the Tempo frame tubing description would infer it is different somehow, possibly in having a butted seat tube.

RaleighSport

That's even more interesting. Especially since the Prelude lists as seamless but the Voyageur does not. I'm in midterm prep mode so I'm glossing over a lot of things apparently.

The Golden Boy 

I could swear I've seen people say they've had 26.8 seatposts.

Scooper

Dave, the catalog specs show the '85 Le Tour and '85 Super Le Tour as having Tenax frames and 26.4mm seatposts, but all of the '86 Tenax frame models show 26.6mm seatposts, all of the '87 Tenax frame models show 26.6mm, all of the '88 Tenax frame models show 26.6mm, and all of the '89 Tenax frame models show 26.6mm seatposts except for the Tempo (27.2mm).

Schwinn specs have had errors before, so the published numbers could be wrong.

Another possibility is that since the I.D. of a 28.6mm O.D. seat tube with 0.9mm walls is 26.8mm with zero tolerance between the I.D. of the seat tube and the O.D. of a 26.8mm seatpost, individual owners could easily ream out the seat tube in order to get a 26.8mm seatpost to fit.

I'm just guessing here...

zazenzach

that's hilarious. I got the exact same answer from columbus. they must have flat out copy pasted to me what they sent the other guy. as the preceeding thread shows, i also tracked down a friend of a friend, someone who used to make these frames in greenville, and he recalled them being basically Cromor as well.

https://www.bikeforums.net/showthread...s-Tenax-Tubing

Scooper

It is pretty funny; for years there's been this question out there with all kinds of speculation, and finally we have the definitive answer as far as I'm concerned.

There will probably be some even more obsessed than we who are still not satisfied and who will keep digging.

cycle_maven

All I know is that my '85 Tenax Tempo has a seam in the seat-tube. I can see it. I don't care what the catalogs say.

himespau 

I'm sort of surprised that Columbus would e-mail that back to you. I would have thought it was some sort of trade secret or something Schwinn would have wanted them not to say for some reason. I guess Schwinn isn't Schwinn anymore though, so it may not matter.

RaleighSport

Only some models 88+ were noted as seamless, it looks indeed like tenax is cromor with possibly some tube swaps...

cycle_maven

Right- I didn't read your whole post carefully-
I guess no mention of "seamless" means it has a seam...

RaleighSport

All good, just wanted to clarify especially since my post was fairly inaccurate.