Serotta CSI Frame 58cm
 

I couldn’t resist trying to capture some Serotta steel frame magic so I pulled the trigger on eBay last week. This appears to be a frame with the “1/2 lugs” joining certain tubes that I’ve read about. So I take it to be earlier production for which those 1/2 lugs took a lot of time to fit and assemble properly. Later on the company had enough capital to have lugs made to order that would accept the Colorado Concept special tube profiles without need to cut lugs to make things fit. Until then, each project was a hand-fit exercise in custom frame building! From the listing:

Measures:
Top tube 58cm center-to-center
Seat tube 58cm center-to-center
Head tube 166mm

Takes 700c wheels, 100/130mm spacing, 1" headtube. Includes Shimano Dura-Ace threaded headset.
Aluminum fork - unknown brand - painted to match.

My photos seem to show a model and serial number? C358L and 367, respectively?

So, a few questions about that 1” threaded aluminum fork. It is not original to the frame right? Seems like a lot of trouble to paint it to match if it wasn’t original to the frame? I have a Kinesis carbon 1 1/8” Threadless fork and head set on hand to sell off to fund a replacement if I want to. Should I? If so, what am I looking for - era-specific or modern - to suit this frame?

CSI 58cm More Photos
 

Here are a few more photos.

Search the catalogs section of the forum and PL member oliver1850 is very knowledgeable about Serotta models, history and serial number translation. That frame most likely came with a steel fork imho.

The ‘L’ on the 58L indicates models with a longer TT. Not sure if the fork is original but if it were me, I’d be looking for a steel fork. Provided everything is straight and in good order, that will be a great ride.

Hmm. Does the frame have any engraved lettering? Like an “S” on the brake bridge or the bottom bracket lug. Those external cable stops on the top tube should also be a big clue. The 58L is supposed to mean a 58cm top tube instead 57.5cm. I also thought csi all started with “cs” not just a “c”. Do any of the tubes appear butted? Thicker at one end than the middle. I’m guessing the head tube lug and seat tube will be the give away.

I don’t know anything about that fork. Folks really like those 1” threaded dura ace headsets so you’ve got some money to play around with if you decide to remove it and sell it.

Hanging parts!
 

I’ve started to build up this frame. SRAM Apex and Rival 11-32, 53/39 gearing (11-speed). I stopped for now at the point where I need to cut cable casings and route cables. I’ve stuck with my Ultegra brakes for awhile now. Dig those rat trap pedals I found at Loose Screws years ago! I will swap these out for another set of Dura-Ace pedals as on my other bike.

I see an engraved “S” on the rear brake stay. I wonder if when they were still using “1/2 lug” assembly they used their on-hand stock of older lugs - perhaps still stamped “C” - before they began sourcing CSI-specific “full” lugs? The filet job on these is stunning though. Yes, the seat and down tubes (at least) are much fatter at the bottom bracket than on the opposite ends.

Colorado Concept tubing, one of Serotta's original ideas in frame design, IIRC.

Good looking frame!

https://i.ebayimg.com/images/g/u0IAA...UJ/s-l1600.jpg

Around this time Serotta made some aluminum frames as well... perhaps that's where that fork came from?

I have the carbon CRL fork from 59L 90s Serotta. F1? PM if interested, I have the orig steel fork I am keeping on it. It is blue, but if you are paint the frame you can paint the fork same time.

I had a CRL which was the predecessor to the CSI. Came with a steel fork. There weren’t aluminum or carbon fork options then as I recall. The F1 came with the Legend I think.

Part of the fun of owning a Serotta is figuring it all out. Did the CSI move to external cable routing on the top tube? The CRL has internal routing. I also feel like the F1 forks were around when the CSI was since when I found my CRL, it had a Woundup, I kinda assumed the F1 wasn’t a thing until the CSI. Got to love those Serotta fades and the brazed lug look is quite unique. I’m excited to see your final build!

Take a look at this thread where various people have posted their Serotta CSi bikes and serial numbers. Lots of details on the evolution/changes over the life of the model.

Our illustrious admin Keith kicks it off with serial #272, and a quick scan makes me think you are in the 1995-6 range, since #808 (serials are sequential by model) was ordered late 1996 and delivered 1997 as noted in an early post.

https://forums.thepaceline.net/showt...serial+numbers

I think that your frame would have typically shipped with the 1" F1 carbon/steel steerer fork--with an all steel fork as an option--but there are more people with more expertise who should correct me if I'm wrong.

And I would have no hesitation in adding Robert's F1 to yours, should you wish to--it would be closer to original than what you have.

(And FWIW--my CSi is as good a steel frame as I have ever thrown a leg over, so enjoy that puppy!)

I completely forgot that some of the csi bikes had those cable stops on the headtube! Oh and location of the serial numbers switched from middle of the BB to the edge at some point too. That is a great thread linked above, thanks.

Man....I remember going in to Gregg's in Seatlle over 20 years ago and drooling over the Serrota's I saw there....I was younger and poor so all I could do was dream. I remember the Lugged steel version with a steel fork I believe....and then they went to a carbon....especailly on the Titanium they began to produce.

From my research trying to date my #268, for what it's worth:
Serial# 198 is a late 1995 model, and 272 is 1996 model, so my 268 is probably early 1996, & CSI-56-808 was Jan 1997.

Thus yours is a 1996. Oh, and from my nosy-ness, the "L" was stamped on all of the CSIs for that year (?? someone check me). Mine has the CS57L but meaures bone stock 57cm. Came with a color matched steel fork, by the way.
Here's a pic
https://i.imgur.com/5KEQ6FTl.jpg