Looking at this frame, fork, headset, and bottom bracket for $100. Already committed and am now shopping for components.

1.) Can anyone tell me the year? This blog says that it is probably 1992-1998 (about 1/3 way down, or use search function):
https://diabloscott.blogspot.com/2000_05_01_archive.html
"This is the font used on Kleins from 1992 through 1998. Sometimes called the Klingon font, I call it Font 2. The letters are still close together but now the K and E are really curvy. Also, this is not a decal, but the letters were masked off before the color coat was added so you're seeing the prime coat of white - Klein called this "debossing", sort of the opposite of embossing I guess... anyway a really cool effect."

Between those years, Bikepedia tells me the Quantum was produced in 1993 and 1995.
Catalogs showing the 1993 and 1995 Kleins having different lettering:
1993: https://www.retrobike.co.uk/gallery2/...g2_itemId=2625
1995: https://www.mtb-kataloge.de/Bikekatal.../Klein1995.pdf

2.) Is it worth it to make this period correct again? Or should I just put modern parts on it?

Pics:

Thanks!

Can you post a picture of the frame you want identified?

It's up there now, don't know if you can see it.

Definitely a 90's frame. Top tube guides and DT shifter bosses. Later models had internal routing.

Looks to be in great shape. Paint does not fade to another shade or change colors in different light, correct?

I have yet to see it in person, but it's pretty safe to say that is the camera (taken on a phone).

Also, seller measured seat tube c-t-c as 52cm. Looks a little bigger than that to me, and 90s models didn't have even numbered seat tubes.

Here's a picture of a decal on the frame if that helps with the ID. Also dropouts.

I like modern parts on classic frames,

Deep rim wheels suit the Kleins because of the fat tubes.

I wouldn't spend too much though, you might think about getting a carbon fork with carbon steerer and a Chris King 1" Threadless headset to convert to threadless and loose a good chuck of weight and improve the ride.

Just wondering what this frame is "worthy" of? I was thinking 105 unless it's nice enough to warrant higher. Also, can anyone estimate the size?

This was a nice racing frame, so if you're going to make it vintage correct, I'd go with 8 speed Ultegra or Dura Ace. Since they were legal, light, and fast back then, it was not uncommon to see it rolling on a pair of Spinergy Rev-X wheels, which you can get pretty cheap on ebay now. Other options for wheels would be Hed Jet, Zipp 440 tubulars (before the 404s), or a set of lightweight handbuilt wheels with low profile hoops. If you want a carbon fork, a Profile or Time fork of that era with a threaded steerer would look appropriate.

If you're going to use undated components, use whatever you want or whatever you get the best deals on. At that point, it's a tool and not a jewel, and it's not nostalgic enough for anyone to shed a tear over.

edit: Looking at other pictures of Klein Quantums, that looks to be about a 56.

Judging by the distance between the top tube and the down tube, it looks more like a 55 cm to me.

Klein made lots of different variants of the Quantum bikes. That makes them hard to identify. As far as I know, there's no reliable serial number information available. After looking at the pictures on Diablo Scott's webpage, my guess is that frame is a 93. That's base on the shifter bosses, top tube brake cable guides, the Klein font, and the placement and font of the model name.

Note that you have a square taper spindle which is pressed into the bottom bracket. That will limit your options for a crankset. There aren't many options for replacing the bottom bracket, either. Unless you swap the fork, you'll need to find a nice 1" stem and compatible handlebars. That said, you can put modern equipment on the bike.

I have an 1983 Klein Performance and a 2006 Klein Q-Pro. PM me if I can help.

I had a 93 Quantum and a 94 Quantum II. My 94 Quantum II had the "Klingon font", like this model. I'd say yours is a 94 Quantum.

Still have fond memories of those bikes. I'd say slap on some Rival or 105 and ride it. Don't worry about the year, whatever you can get your hands on. The only thing you have to be careful of is the square taper bottom bracket length. Back in the day, different levels of Shimano had different spindle lengths. IIRC correctly, Dura Ace was 108mm and Ultegra (600) was 112? Something like that. You just need to find a mid-90's square taper crank that's compatible with the bottom bracket.