The most recent photos of RidesaJapanese's Blue 10 speed SUBURBAN does confirm Metacortex's suspicion that it is a 1974 and that RidesaJapanese simply mistakenly listed EN 510423 as the serial when it likely actually is EK 510423. It does not have the Shimano FFS that a 1977 model would have. You can clearly see that from the latest picture.

If it were my bicycle, I would get rid of that Huret Alvit SCHWINN APPROVED REAR DERAILLEUR that came on ten speed Varsity/Continental and ten speed Suburban models. REPLACE IT WITH A SHIMANO EAGLE or SHIMANO SKYLARK or THE GT-120 from the '74-'77 Collegiate 5 speed/Suburban 5 speed, - OR- the GT-100 from the '70 -'73 Collegiate 5 speed/Sububurban 5 speed, -OR- a NOS(new old stock) SUNTOUR rear derailleur from the seventies.
Whether it is an OLD SCHWINN or an OLD RALEIGH or whatever it is, IF IT HAS A HURET or SIMPLEX or even that Italian C - word that the fools love so much, it gets replaced by superior Japanese equipment. If you have a vintage bike that is worth serious dough such that inferior originality will be better for market value, then keep it stock, but if not, you should say these words: JAPAN = great and Europe = no good.


Pernlundell4: I don't see any advancement that you will gain from Index shifting on your 1975 SUBURBAN.
The SUBURBAN five speed with the SHIMANO built GT-120 is bullet proof and shifts consistantly decent. The Schwinn Stem Shifter is one of the best stem shifters in my opinion. Like I mentioned before, if you have the TEN SPEED Suburban then it has the INFERIOR Huret Schwinn Approved Rear derailleur that I personally would REPLACE with a Shimano Eagle, Shimano Skylark, GT-120, GT-100 or a SUNTOUR rear derailleur.
The Five speed SUBURBAN also has a better FREEWHEEL than the ten speed Suburban/Varsity/continental has.
The Model J is superior in quality to the Model F freewheel, although the Model F freewheel is very good.
The Low Gearing (hill climbing ability) is Superior in the Model J freewheel.
The Model J has a 32 TEETH first gear. The Model F has a 28 TEETH first gear.
Model J has 32, 26, 21, 17, 14
Model F has 28, 24, 20, 16, 14

Nothing is wrong with Friction shifting.
It is incredibly simple to set up a Shimano Eagle, Shimano Skylark, or shimano built GT-120 Schwinn Approved rear derailleur since they all have the high and low Limit screws in the typical shimano location. The 1970 Collegiate 5 speed and 1970 Suburban 5 speed were about the first bicycles other than Japanese bicycles to feature Shimano built rear derailleurs. Shimano wiped out the Europeans by 1977 because their quality was twice as good and at half the price. Shimano Eagle was found on hundreds of thousands of inexpensive Kmart and no-name Japanese import ten speeds of the 1972 to 1977 era. Yes it was their low line derailleur but the only difference is that it is heavier and has a massive bash guard to protect it. Yes, that extra weight isn't something racers want but the durability and the operational quality cannot be beat. Go see what Mr Brown thought of the Shimano Eagle. (see sheldon brown website...).
Yep, all those kmart ten speeds came with Shimano Eagle rear derailleurs, and they put to shame every one of those Alvit rear derailleurs that were seen on all those Raleigh ten speeds before 1977, and the Varsity/Continental and Suburban ten speeds of the seventies and before.
I would not waste my time and money trying to convert a 1975 SUBURBAN to index shifting. The Schwinn stik on the stem does the job adequately.
So don't think Hooray for Huret, think wastebasket, rubbish bin for Huret rear derailleurs, and just go with Japanese superiority.
It is easy to swap to a Shimano rear derailleur or a Suntour, so why ride something that is not nearly as good. Yes, the Huret rear derailleur is functional and dependable enough but compared to the Shimano product or Maeda SUNTOUR rear derailleurs, it is 2nd rate by a country mile.
The SUBURBAN is a really decent bicycle if you are of the mindset of stay thin, ride a Schwinn.......the extra weight will do you some good.
The basic Electroforged SCHWINN bicycles with five or more gears of the SEVENTIES that are outstanding in stock configuration are the FIVE SPEED Collegiate, the FIVE SPEED SUBURBAN, and the SPORTABOUT ten speed ( circa '77-'78 essentially a SUNTOUR equipped Varsity) and the RUNABOUT (circa '77-'78 essentially a SUNTOUR equipped Tourist Style Varsity/Suburban ten speed).
IF YOU WANT A FANCIER SUBURBAN, THEN PERHAPS FIND A 1977 and later model with the FFS.
Enjoy the Suburban.
Schwinns from Chicago are not everybody's favorites but they have certain characteristics which make them among the most durable bicycles ever made. Significant weight is a byproduct of the strength and durability of all its components. Weight is not a bad thing if you aren't racing, or climbing very steep hills.