Why so many December ‘80 frames?

[GTs58]

I just picked this one up. It isn't quite the bike I wanted but I bought it from a 82 year old Marine Vet that rode the beach all the time. He got sick and couldn't ride anymore, So, I am going to clean it up and make it my new beach cruiser, #MR909685, Dec 1980. I am guessing it is a Cruiser model. It does have skinnier wheels (stamped made in china). So first thing I will need to find are some S-2's.

Edit: There are no numbers on the badge. Guessing it was replaced at some point

View attachment 1755055

View attachment 1755056

You going to shoot some new paint on that poor thing? There were a couple MR 9xx,xxx's posted in this thread, just see what the head badge dates were and find one close to that time period.

 

[PD Monkey]

You going to shoot some new paint on that poor thing? There were a couple MR 9xx,xxx's posted in this thread, just see what the head badge dates were and find one close to that time period.

Yeah, I am not sure how far I am going to go with this one. Maybe powdercoat it. It looks like it was originally blue and spray painted red. @GTs58 I can't read the chain guard. How do I tell what model it is/was? Clearly nothing is original. My limited knowledge based on age, I would say Spitfire or Cruiser. What do you think?

 

[dihummer]

I just found this thread and find it very interesting.

I will give my theory on the "MR" data code later in this post.

I was doing research on early Schwinn mountain bicycles and Schwinn pre-All Terrain bicycles and I stumbled across this thread. I am trying to date the production of these bicycles and the Schwinn serial number date codes are useful. I am looking at Schwinn Chicago factory serial number date codes from 1980 to the factories closing, near the end of 1983.
As is generally well understood the second letter in the serial number is for the year:
R = 1980
S = 1981
T = 1982
U = 1983

The strike at the Chicago factory was during this period, beginning in late October 1980 and ending in early February 1981.

Many manufacturers use date codes on their products and they serve a variety of functions, including:
a. Inventory management: use your oldest inventory first,
b. production accounting: how many of an item were produced in a month.
c. quality control: Are customers returning a large number of product from a given month? Was there a quality issue that month?

I have collected a lot of serial numbers for Schwinn branded bicycles.

Here are some observations I have made about 1980s Schwinn Chicago bicycle production, based on my serial number data.

1. The six digit numbers following the date code letters are not entirely sequential.
The numbers may be sequential within discrete and widely separate ranges for a given month.

2. I have not seen LR date codes, November 1980, the first full month of the strike.

3. For the year code S, 1981, I have not seen serial numbers for months A through H, January to August.
The month code A, for January, would be a full month of the strike.
The month code B, for February, would be a partial month of the strike.
The 1981 month codes I have are J and K, September and October.

4. For the year code T, 1982, I have month codes A, C, E, F, G, J, and L. Seven months of the year.


5. For the year code U, 1983, I have month codes A, B, C, D, E, F, G, J, and K. Nine of the first ten months.


6. There are an excessive number of MR codes, December 1980. I have 42 observations with this month/year code.
From my data for serial numbers from 1970 to 1983, I have only four other months with more than 10 observations.
CH = March 1972
JH = August 1972
CJ = March 1973, (many Schwinn Super Sport observations)
GJ = July 1973, (many Schwinn Superior observations)

All of these months are at the height of the "Bike Boom" when Schwinn and other manufacturers could not keep up with demand.

7. Most of the headbadge date codes for the MR serial number frames are for the year 1981 and I have seen none for the year 1980.
The headbadge date codes that I have seen go from:
0971 to 2941, April 1981 to October 1981,
with three 1982 date codes (0112, 0182, 0912),
and one 1983 date code (1023).



So here is my theory of the "MR" date code in the Schwinn Chicago serial numbers. I will give my theory in point form as it appears to be more than one theory, more like a story. This is just my theory and you are welcome to rip the theory or individual points to shreds.


1. The MR date code does not represent December 1980 bicycle frame production from Schwinn Chicago.

2. Frame production was shutdown during the 13 or 14 weeks of the strike.
It makes no economic sense to start up expensive production facilities if there is not enough staff to maximize production. I have seen no frame serial numbers for November 1980 or January 1981, both months during the strike period.

3. During the strike, bicycle assembly may have continued using stockpiled frames. This would explain some of the head badge date codes with a date during the period of the strike.


4. The MR date code represents the frame production for several months after the 1980 strike ended in early February 1981.
This is borne out in part by observation no. 7, about the head badge date codes.

5. The six digit number range for MR date code serial numbers: MR517022 to MR912227.
Assuming that the numbers are sequential this is a range of approximately 400,000 bicycles. I think this is more than one months production from Schwinn Chicago. But the assumption of sequential numbers may be faulty.
According to the Schwinn Reporter, the two largest years of bicycle shipments by Schwinn, 1973 and 1974, the total shipments were a little more 1,550,000 bicycles. This total included bicycles from Japan.

It is difficult to see how Schwinn Chicago could manufacture much more than 200,000 bicycle frames per month.

Based on the above information, can a conclusion be made that the MR serial numbers represent more than one month?

I am not an expert on Schwinn bicycle production numbers.
I am sure that someone knows Schwinn bicycle production and can provide a better insight.


6. Why would Schwinn in Chicago have used the MR code for multiple month?

Schwinn management probably planned to close the Chicago facility as quickly as possible. Therefore it was no longer essential to strictly follow inventory management protocols.

If the facility is closing, why continue inventory management, production accounting, or quality control protocols?

7. Why did Schwinn management resume the serial number date code protocol late in 1981?

Schwinn needed to provide bicycles for all the Schwinn dealers. Maybe Schwinn management could not replace the Chicago production as quickly as they had hoped. Panasonic in Japan and Giant in Taiwan supplied Schwinn bicycles during the strike and several years after. By 1983 the Greenville, Mississippi facility was operating.

Chicago production continued into late 1983, hence the need to resume the serial number date protocol.



Conclusion

The "MR" serial numbers were used for more than one months frame production after the 1980-81 strike at the Chicago facility.

That is my theory, but more data is needed. More data in the form of serial numbers and head badge date codes.

Can anyone find serial numbers for month LR, November 1980? This is the first full month of the strike.

Can anyone find year S serial numbers, 1981? In particular months A through H, January to August 1981.

More MR serial numbers with head badge date codes?

 

[GTs58]

I just found this thread and find it very interesting.

I will give my theory on the "MR" data code later in this post.

I was doing research on early Schwinn mountain bicycles and Schwinn pre-All Terrain bicycles and I stumbled across this thread. I am trying to date the production of these bicycles and the Schwinn serial number date codes are useful. I am looking at Schwinn Chicago factory serial number date codes from 1980 to the factories closing, near the end of 1983.
As is generally well understood the second letter in the serial number is for the year:
R = 1980
S = 1981
T = 1982
U = 1983

The strike at the Chicago factory was during this period, beginning in late October 1980 and ending in early February 1981.

Many manufacturers use date codes on their products and they serve a variety of functions, including:
a. Inventory management: use your oldest inventory first,
b. production accounting: how many of an item were produced in a month.
c. quality control: Are customers returning a large number of product from a given month? Was there a quality issue that month?

I have collected a lot of serial numbers for Schwinn branded bicycles.

Here are some observations I have made about 1980s Schwinn Chicago bicycle production, based on my serial number data.

1. The six digit numbers following the date code letters are not entirely sequential.
The numbers may be sequential within discrete and widely separate ranges for a given month.

2. I have not seen LR date codes, November 1980, the first full month of the strike.

3. For the year code S, 1981, I have not seen serial numbers for months A through H, January to August.
The month code A, for January, would be a full month of the strike.
The month code B, for February, would be a partial month of the strike.
The 1981 month codes I have are J and K, September and October.

4. For the year code T, 1982, I have month codes A, C, E, F, G, J, and L. Seven months of the year.


5. For the year code U, 1983, I have month codes A, B, C, D, E, F, G, J, and K. Nine of the first ten months.


6. There are an excessive number of MR codes, December 1980. I have 42 observations with this month/year code.
From my data for serial numbers from 1970 to 1983, I have only four other months with more than 10 observations.
CH = March 1972
JH = August 1972
CJ = March 1973, (many Schwinn Super Sport observations)
GJ = July 1973, (many Schwinn Superior observations)

All of these months are at the height of the "Bike Boom" when Schwinn and other manufacturers could not keep up with demand.

7. Most of the headbadge date codes for the MR serial number frames are for the year 1981 and I have seen none for the year 1980.
The headbadge date codes that I have seen go from:
0971 to 2941, April 1981 to October 1981,
with three 1982 date codes (0112, 0182, 0912),
and one 1983 date code (1023).



So here is my theory of the "MR" date code in the Schwinn Chicago serial numbers. I will give my theory in point form as it appears to be more than one theory, more like a story. This is just my theory and you are welcome to rip the theory or individual points to shreds.


1. The MR date code does not represent December 1980 bicycle frame production from Schwinn Chicago.

2. Frame production was shutdown during the 13 or 14 weeks of the strike.
It makes no economic sense to start up expensive production facilities if there is not enough staff to maximize production. I have seen no frame serial numbers for November 1980 or January 1981, both months during the strike period.

3. During the strike, bicycle assembly may have continued using stockpiled frames. This would explain some of the head badge date codes with a date during the period of the strike.


4. The MR date code represents the frame production for several months after the 1980 strike ended in early February 1981.
This is borne out in part by observation no. 7, about the head badge date codes.

5. The six digit number range for MR date code serial numbers: MR517022 to MR912227.
Assuming that the numbers are sequential this is a range of approximately 400,000 bicycles. I think this is more than one months production from Schwinn Chicago. But the assumption of sequential numbers may be faulty.
According to the Schwinn Reporter, the two largest years of bicycle shipments by Schwinn, 1973 and 1974, the total shipments were a little more 1,550,000 bicycles. This total included bicycles from Japan.

It is difficult to see how Schwinn Chicago could manufacture much more than 200,000 bicycle frames per month.

Based on the above information, can a conclusion be made that the MR serial numbers represent more than one month?

I am not an expert on Schwinn bicycle production numbers.
I am sure that someone knows Schwinn bicycle production and can provide a better insight.


6. Why would Schwinn in Chicago have used the MR code for multiple month?

Schwinn management probably planned to close the Chicago facility as quickly as possible. Therefore it was no longer essential to strictly follow inventory management protocols.

If the facility is closing, why continue inventory management, production accounting, or quality control protocols?

7. Why did Schwinn management resume the serial number date code protocol late in 1981?

Schwinn needed to provide bicycles for all the Schwinn dealers. Maybe Schwinn management could not replace the Chicago production as quickly as they had hoped. Panasonic in Japan and Giant in Taiwan supplied Schwinn bicycles during the strike and several years after. By 1983 the Greenville, Mississippi facility was operating.

Chicago production continued into late 1983, hence the need to resume the serial number date protocol.



Conclusion

The "MR" serial numbers were used for more than one months frame production after the 1980-81 strike at the Chicago facility.

That is my theory, but more data is needed. More data in the form of serial numbers and head badge date codes.

Can anyone find serial numbers for month LR, November 1980? This is the first full month of the strike.

Can anyone find year S serial numbers, 1981? In particular months A through H, January to August 1981.

More MR serial numbers with head badge date codes?

During the strike Schwinn produced MR serial stamped head tubes and the highest number I've seen was 995XXX. So there is a good chance Schwinn produced 999,999 MR serial stamped head tubes. These head tubes were used in building frames all thru the 1981 production with some being used in the 1982 production. The numbers were stamped in sequential order, but the head tubes were not used in any sequential order. They were also used on frames that were sold as frames in their accessory catalogs for 1981 and later. Murray took over the 1983 Schwinn production starting in November 1982. Schwinn supplied Murray with parts and at the very beginning for a few months they supplied Murray with Schwinn built frames.

Sept. 1982 announcement.........

 

[Oilit]

I just found this thread and find it very interesting.

I will give my theory on the "MR" data code later in this post.

I was doing research on early Schwinn mountain bicycles and Schwinn pre-All Terrain bicycles and I stumbled across this thread. I am trying to date the production of these bicycles and the Schwinn serial number date codes are useful. I am looking at Schwinn Chicago factory serial number date codes from 1980 to the factories closing, near the end of 1983.
As is generally well understood the second letter in the serial number is for the year:
R = 1980
S = 1981
T = 1982
U = 1983

The strike at the Chicago factory was during this period, beginning in late October 1980 and ending in early February 1981.

Many manufacturers use date codes on their products and they serve a variety of functions, including:
a. Inventory management: use your oldest inventory first,
b. production accounting: how many of an item were produced in a month.
c. quality control: Are customers returning a large number of product from a given month? Was there a quality issue that month?

I have collected a lot of serial numbers for Schwinn branded bicycles.

Here are some observations I have made about 1980s Schwinn Chicago bicycle production, based on my serial number data.

1. The six digit numbers following the date code letters are not entirely sequential.
The numbers may be sequential within discrete and widely separate ranges for a given month.

2. I have not seen LR date codes, November 1980, the first full month of the strike.

3. For the year code S, 1981, I have not seen serial numbers for months A through H, January to August.
The month code A, for January, would be a full month of the strike.
The month code B, for February, would be a partial month of the strike.
The 1981 month codes I have are J and K, September and October.

4. For the year code T, 1982, I have month codes A, C, E, F, G, J, and L. Seven months of the year.


5. For the year code U, 1983, I have month codes A, B, C, D, E, F, G, J, and K. Nine of the first ten months.


6. There are an excessive number of MR codes, December 1980. I have 42 observations with this month/year code.
From my data for serial numbers from 1970 to 1983, I have only four other months with more than 10 observations.
CH = March 1972
JH = August 1972
CJ = March 1973, (many Schwinn Super Sport observations)
GJ = July 1973, (many Schwinn Superior observations)

All of these months are at the height of the "Bike Boom" when Schwinn and other manufacturers could not keep up with demand.

7. Most of the headbadge date codes for the MR serial number frames are for the year 1981 and I have seen none for the year 1980.
The headbadge date codes that I have seen go from:
0971 to 2941, April 1981 to October 1981,
with three 1982 date codes (0112, 0182, 0912),
and one 1983 date code (1023).



So here is my theory of the "MR" date code in the Schwinn Chicago serial numbers. I will give my theory in point form as it appears to be more than one theory, more like a story. This is just my theory and you are welcome to rip the theory or individual points to shreds.


1. The MR date code does not represent December 1980 bicycle frame production from Schwinn Chicago.

2. Frame production was shutdown during the 13 or 14 weeks of the strike.
It makes no economic sense to start up expensive production facilities if there is not enough staff to maximize production. I have seen no frame serial numbers for November 1980 or January 1981, both months during the strike period.

3. During the strike, bicycle assembly may have continued using stockpiled frames. This would explain some of the head badge date codes with a date during the period of the strike.


4. The MR date code represents the frame production for several months after the 1980 strike ended in early February 1981.
This is borne out in part by observation no. 7, about the head badge date codes.

5. The six digit number range for MR date code serial numbers: MR517022 to MR912227.
Assuming that the numbers are sequential this is a range of approximately 400,000 bicycles. I think this is more than one months production from Schwinn Chicago. But the assumption of sequential numbers may be faulty.
According to the Schwinn Reporter, the two largest years of bicycle shipments by Schwinn, 1973 and 1974, the total shipments were a little more 1,550,000 bicycles. This total included bicycles from Japan.

It is difficult to see how Schwinn Chicago could manufacture much more than 200,000 bicycle frames per month.

Based on the above information, can a conclusion be made that the MR serial numbers represent more than one month?

I am not an expert on Schwinn bicycle production numbers.
I am sure that someone knows Schwinn bicycle production and can provide a better insight.


6. Why would Schwinn in Chicago have used the MR code for multiple month?

Schwinn management probably planned to close the Chicago facility as quickly as possible. Therefore it was no longer essential to strictly follow inventory management protocols.

If the facility is closing, why continue inventory management, production accounting, or quality control protocols?

7. Why did Schwinn management resume the serial number date code protocol late in 1981?

Schwinn needed to provide bicycles for all the Schwinn dealers. Maybe Schwinn management could not replace the Chicago production as quickly as they had hoped. Panasonic in Japan and Giant in Taiwan supplied Schwinn bicycles during the strike and several years after. By 1983 the Greenville, Mississippi facility was operating.

Chicago production continued into late 1983, hence the need to resume the serial number date protocol.



Conclusion

The "MR" serial numbers were used for more than one months frame production after the 1980-81 strike at the Chicago facility.

That is my theory, but more data is needed. More data in the form of serial numbers and head badge date codes.

Can anyone find serial numbers for month LR, November 1980? This is the first full month of the strike.

Can anyone find year S serial numbers, 1981? In particular months A through H, January to August 1981.

More MR serial numbers with head badge date codes?

Interesting theory! I haven't thought about the other months during and immediately after the strike, now I will have to keep an eye out. I have seen a few 1981 "S" serials but I never paid attention to the month. Your idea that the MR serials represent more bicycles than Schwinn could produce in a month is probably correct, but if Schwinn was only producing parts the normal constraints may not have applied. We may never know all the answers, but your guess is as good as any. I keep hoping that someone who was working there might run across this thread and fill in some of the blanks, but not so far.

 

[GTs58]

Schwinn had a total of 1,297,431 units boxed up out the door for 1979, and that includes imported non-Schwinn built bikes. How long would it take Schwinn to use up 999,999 MR stamped head tubes for just the EF'd frames? Schwinn was stamping roughly 4200 dropouts per day in 1968. There is a lot more work involved in making a head tube than there is in making a dropout. So did the daily stampings continue at a rate of 4 to 5K pieces per day? With a million MR head tubes, that stock should have lasted for quite some time so no need to keep stamping more every month in 1981.

 

[Rusty Klunker]

I just found this thread and find it very interesting.

I will give my theory on the "MR" data code later in this post.

I was doing research on early Schwinn mountain bicycles and Schwinn pre-All Terrain bicycles and I stumbled across this thread. I am trying to date the production of these bicycles and the Schwinn serial number date codes are useful. I am looking at Schwinn Chicago factory serial number date codes from 1980 to the factories closing, near the end of 1983.
As is generally well understood the second letter in the serial number is for the year:
R = 1980
S = 1981
T = 1982
U = 1983

The strike at the Chicago factory was during this period, beginning in late October 1980 and ending in early February 1981.

Many manufacturers use date codes on their products and they serve a variety of functions, including:
a. Inventory management: use your oldest inventory first,
b. production accounting: how many of an item were produced in a month.
c. quality control: Are customers returning a large number of product from a given month? Was there a quality issue that month?

I have collected a lot of serial numbers for Schwinn branded bicycles.

Here are some observations I have made about 1980s Schwinn Chicago bicycle production, based on my serial number data.

1. The six digit numbers following the date code letters are not entirely sequential.
The numbers may be sequential within discrete and widely separate ranges for a given month.

2. I have not seen LR date codes, November 1980, the first full month of the strike.

3. For the year code S, 1981, I have not seen serial numbers for months A through H, January to August.
The month code A, for January, would be a full month of the strike.
The month code B, for February, would be a partial month of the strike.
The 1981 month codes I have are J and K, September and October.

4. For the year code T, 1982, I have month codes A, C, E, F, G, J, and L. Seven months of the year.


5. For the year code U, 1983, I have month codes A, B, C, D, E, F, G, J, and K. Nine of the first ten months.


6. There are an excessive number of MR codes, December 1980. I have 42 observations with this month/year code.
From my data for serial numbers from 1970 to 1983, I have only four other months with more than 10 observations.
CH = March 1972
JH = August 1972
CJ = March 1973, (many Schwinn Super Sport observations)
GJ = July 1973, (many Schwinn Superior observations)

All of these months are at the height of the "Bike Boom" when Schwinn and other manufacturers could not keep up with demand.

7. Most of the headbadge date codes for the MR serial number frames are for the year 1981 and I have seen none for the year 1980.
The headbadge date codes that I have seen go from:
0971 to 2941, April 1981 to October 1981,
with three 1982 date codes (0112, 0182, 0912),
and one 1983 date code (1023).



So here is my theory of the "MR" date code in the Schwinn Chicago serial numbers. I will give my theory in point form as it appears to be more than one theory, more like a story. This is just my theory and you are welcome to rip the theory or individual points to shreds.


1. The MR date code does not represent December 1980 bicycle frame production from Schwinn Chicago.

2. Frame production was shutdown during the 13 or 14 weeks of the strike.
It makes no economic sense to start up expensive production facilities if there is not enough staff to maximize production. I have seen no frame serial numbers for November 1980 or January 1981, both months during the strike period.

3. During the strike, bicycle assembly may have continued using stockpiled frames. This would explain some of the head badge date codes with a date during the period of the strike.


4. The MR date code represents the frame production for several months after the 1980 strike ended in early February 1981.
This is borne out in part by observation no. 7, about the head badge date codes.

5. The six digit number range for MR date code serial numbers: MR517022 to MR912227.
Assuming that the numbers are sequential this is a range of approximately 400,000 bicycles. I think this is more than one months production from Schwinn Chicago. But the assumption of sequential numbers may be faulty.
According to the Schwinn Reporter, the two largest years of bicycle shipments by Schwinn, 1973 and 1974, the total shipments were a little more 1,550,000 bicycles. This total included bicycles from Japan.

It is difficult to see how Schwinn Chicago could manufacture much more than 200,000 bicycle frames per month.

Based on the above information, can a conclusion be made that the MR serial numbers represent more than one month?

I am not an expert on Schwinn bicycle production numbers.
I am sure that someone knows Schwinn bicycle production and can provide a better insight.


6. Why would Schwinn in Chicago have used the MR code for multiple month?

Schwinn management probably planned to close the Chicago facility as quickly as possible. Therefore it was no longer essential to strictly follow inventory management protocols.

If the facility is closing, why continue inventory management, production accounting, or quality control protocols?

7. Why did Schwinn management resume the serial number date code protocol late in 1981?

Schwinn needed to provide bicycles for all the Schwinn dealers. Maybe Schwinn management could not replace the Chicago production as quickly as they had hoped. Panasonic in Japan and Giant in Taiwan supplied Schwinn bicycles during the strike and several years after. By 1983 the Greenville, Mississippi facility was operating.

Chicago production continued into late 1983, hence the need to resume the serial number date protocol.



Conclusion

The "MR" serial numbers were used for more than one months frame production after the 1980-81 strike at the Chicago facility.

That is my theory, but more data is needed. More data in the form of serial numbers and head badge date codes.

Can anyone find serial numbers for month LR, November 1980? This is the first full month of the strike.

Can anyone find year S serial numbers, 1981? In particular months A through H, January to August 1981.

More MR serial numbers with head badge date codes?

As I'm sure you've read the SNs were stamped while the head tube was a flat piece of metal. I have no idea how long it was till it was shaped into the head tube and then later an assembled frame.
So it was probably just a flat piece of metal stacked up.
Seems like during normal production SN stamp was about two months prior to build date stamp.

I was no where near Chicago, and knew no one that worked at Schwinn in 1980 but in prior years to the strike Schwinn shut down for 2+ weeks for the Christmas holiday. Were they still stamping numbers during that time in 1980 idk.

Schwinn also closed for 2 weeks fir the 4th of July.

 

[GTs58]

The making and serial stamping. The serial stamping and badge holes were the last things done.

 

[Rusty Klunker]

The making and serial stamping. The serial stamping and badge holes were the last things done.

View attachment 2027532

Thats funny, I could have sworn you were the one saying they were stamped when they were flat.
So they were stamped on the head tube before the head was installed on the bike. Safe to say frames weren't stacking up but rather head tubes.

 

[GTs58]

Thats funny, I could have sworn you were the one saying they were stamped when they were flat.
So they were stamped on the head tube before the head was installed on the bike. Safe to say frames weren't stacking up but rather head tubes.

Yeah I always thought the serials were stamped when it was still a flat piece of metal until that reporter straighten me out. It makes more sense stamping it when it’s flat but the number would probably get damaged when they’re cleaning up the welding slag at the center of the tubes.