9volt 

Can anyone ID this frame? Dropouts are Shimano UF, fork is Tange, it had 80/81 dated 600 Arabesque parts on it. More pics available. Thanks!

SN appears to be MU06494

3speedslow

Looks interesting! Pics of the whole bike, pls.

Have you pulled the fork?

9volt 

Here's the frame and fork. Fork is stamped Tange OL

3speedslow

Nothing is coming to mind except the earlier thoughts of a well made early 80's frame. Those rear drop outs are throwing that off though. Nice details but plain in other areas.

Right now, a personal frame one off?

3speedslow

Just saw the shifter brazenings, maybe bumps it up to mid 80's.

9volt 

The HS, crank, shifters, and derailleurs were Arabesque. I figured that pointed to original pieces but it seems just as likely they were swapped in when the frame was painted.

9volt 

Bump?

T-Mar

The fork is coded for December 1980, which matches the components. My original thought was that the serial number was consistent for a 1985 Miyata manufactured in late 1984 but that's at odds with the components and fork. However, Tsunoda used a similar format and their M-codes are circa 1981, so a Lotus would be a candidate. Lotus had a few models with different degrees of 600EX in the very early 1980s. Given the repaint it is possible that some features have been added, which may complicate identification.

JohnDThompson 

My guess is a mid-level Japanese production frame from the early 1980s. It looks pretty clean, but nothing really calls out high-end custom work.

Hummer

The serial number for Tsunoda manufactured frames. The cable guides under the BB are also Tsunoda type.

The first character "M" is probably for the year 1981. The second letter "U" is for the month, but I do not know which month.

This is based in large part on the serial numbers of Lotus collected by @Snyderman.

Serial Number Project Information

T-Mar

The only Lotus models featuring cable routing under the shell in 1981-982 were the three racing models. It's obviously not the Super Pro, as it lacks the aero tubeset. Similarly the Supreme had brazed-on shift lever bosses. The Competition fits the general configuration of cable routing under the BB shell, vertical dropouts and brazed-on bottle bosses, cable tunnels and cable stops but no shift lever bosses. This model did use 600EX during this period but only for the crankset and brakeset.

Hummer

I did not state that the bicycle was branded as a Lotus. I said the frame was manufactured by Tsunoda.

Much of the available Tsunoda serial number data comes from Lotus branded bicycle.

Several brand names have Tsunoda frames, including Tsunoda.

9volt 

Thanks for all the info. There is no evidence of headbadge mount holes and from what I've seen the Lotus badges have two rivets.

Hummer

@9volt, this bicycle may be a match for your frame:

https://www.steel-vintage.com/tsunod...e-1980s-detail

T-Mar

I wasn't commenting on you post but following up on my earlier post (#8), where I noted that the serial number format was similar with Tsunoda's and that Lotus was a possible candidate.

lukepro

Hi, got tsunoda i.c. exacly the same

lukepro

The Golden Boy 

Mystery solved, Gang!

"I would have gotten away with it, if it hadn't been for those meddling kids and their dog!"