Cdubb79w

Hi all,

Recently was given some old bikes but the subject of this is a old Schwinn Varsity. The derailers are broken, I know the bike isn’t worth anything but the paint and bars are still good so I want to convert it into a single speed so I can do something with it. I know I could just remove the derailers and shorten the chain but I would rather install a purpose built single speed freewheel onto the factory wheel.

My question for the gurus is, one, is this doable? And what thread is on that factory hub?

There are plenty of cheap single speed freewheels out there I just need to know what will thread on to the hub. I know spacing and chain alignment are key, I haven’t measured that yet but I am aware of their importance.

I can’t post links yet but if you go on eBay and see a $8-11 12T freewheel that basically what I am looking for but I am open to suggestions too of course. Cheaper the better!

Geepig

Very doable, the gears are mounted on a standard thread hub and I am sure that it will not be difficult to find a single speed hub to fit. You might have to redish the wheel to get the alignment.

The other option is buy a secondhand rear wheel, they are not what you would call hard to find, and you might even find a donor bike with extra parts that might come in handy. 'Ladies' bikes are often a good, cheaper source.

Good luck.

Vintage Schwinn

Cdubb:
Assuming that you have the typical bike-boom era Varsity of the late sixties to late seventies, IT HAS A FREEWHEEL (model F) with 28-24-20-16-14 -and- 39 & 52 in front.

Perhaps, a much better, as well as much less expensive way to proceed, would be to simply find any old used Shimano LARK, SKYLARK, EAGLE or similar basic "Lark Copy"........................all of those have the old timey hanging claw that mount on to ancient late '60's and '70's bicycles like Varsities and millions of 10 speeds from the seventies.......they fit perfectly and are so simple that you can easily install and adjust EVEN IF YOU HAVE NEVER DONE SO BEFORE.
These are Super Simple and the typical location for the Shimano LOW limit and HIGH limit screws.


There are some NEW el-cheapo "lark knockoffs" that you can buy for less than $10 total including shipping, typically between about $6 and $9.98 or so. YES, THEY ARE CHINESE AND SOMEWHAT CRUDE, BUT ARE knockoffs of the 1967 to 1973 era Lark, except that these modern Chinese knockoffs do not employ the same high quality materials that the fifty year old Shimano has. Still, even with the weaker and crappy materials, these NEW el-cheapo "lark knockoffs" do function okay.
You can find such NEW "lark knockoffs" with the names ' XUNDAH ' and ' FALCON ' and a few other meaningless names along the chrome cover bashguards.
Yes, these NEW "lark knockoffs" are HEAVY like the old basic rear derailleurs were back then. EXPECT THEM TO WEIGH IN EXCESS OF 300 grams!!! Many people use them to replace malfunctioning and damaged lightweight black colored no-name and as replacements for damaged, super cheapo modern day Shimano derailleurs that come as factory equipment on $89 to $250 Wal-Mart / Target / Dick's / various web sellers' bicycles. These HEAVY new "lark knockoffs" are more durable when subjected to harsh abuse of throwing the bikes on the ground and other mistreatment than modern lightweight derailleurs are. Yes, the shifting can be klunky but if adjusted and oiled, these el-cheapo NEW "lark knockoffs" do function well enough and are reliable until wear & fatigue of certain parts becomes such that you should replace the XUNDAH or FALCON, etc with another NEW unit. Yes, the Seventies era SHIMANO and Maeda SUNTOUR rear derailleurs will far outlast one of these el-cheapo XUNDAH or FALCON lark knockoffs because of the materials, but these el-cheapo lark knockoffs will likely survive five to ten years of use with minimal care. These el-cheapo XUNDAH or FALCON lark knockoffs are Short Cage and generally work well with 28 Max COG and with FIVE SPEED Freewheels, and SIX and SEVEN speed Freewheels USING FRICTION SHIFTING.

********Keeping the existing VARSITY's freewheel (model F) with 28-24-20-16-14 and REPLACING the REAR DERAILLEUR, and ELIMINATING THE FRONT DERAILLEUR, essentially converting the old Varsity into a FIVE SPEED like the 5 sp Collegiate model ---OR---- like the 5 sp Suburban model.
Yes, you'd have to make a decision about what to USE for the FRONT CRANK Chainwheel !!! You do have 52 or 39 currently, that you could choose from BUT YOU WOULD PROBABLY BETTER SERVED choosing an aftermkt (42 Teeth) single replacement steel chainwheel. Beach cruiser suppliers and bmx suppliers have such various sized , from 40T, 42T, 44T, 46T etc , new chainwheels that are inexpensive, ~ approx $20 or less.
Why (42T) ? It would give a good compromise of basic hill tackling ability and top-end cruising. Here is why:
Varsity.......................14..................16.......................20.....................24 ...................28....................rear cogs.............
(42T).........GEAR.......81...................71......................57.....................47..... ..............41.....................GEAR................

The existing 52T large front cog WOULD BE USELESS unless you have ZERO HILLS in your everyday riding activity!
The existing 39T small front cog MIGHT GIVE YOU BETTER hill climbing than (42T) BUT IT MIGHT NOT GIVE YOU THE CRUISING SPEED THAT YOU'D ACCEPT.
*******************the GEAR range of 41 to 81 for (42T) is adequate for most situations, HOWEVER YOU CAN CALCULATE AND DETERMINE FOR YOURSELF AS TO WHAT MIGHT BE THE BEST Front Teeth Number to Select. There is not one size that fits all persons' needs..........DECIDE WHAT IS BEST FOR YOU!!

******* I am sure that you must be thinking, oh why not just Go With the 46T Clover or Mag style SCHWINN front crankwheel as the old five speed COLLEGIATE & 5 speed SUBURBAN has. Well here is why: THE SUBURBAN has 46T front but it has the Model J freewheel with 32-26-21-17-14.
The 1970 and later COLLEGIATE five speed has the same Model J freewheel with 32-26-21-17-14, and the same 46T front.
The 1964 thru 1969 COLLEGIATE five speed has that old Model F freewheel of Varsity with 28-24-20-16-14 and the 46T front.
THE 1964 thru 1969 COLLEGIATE five speeds ARE LESS DESIREABLE than the 1970 and later BECAUSE THE GEAR RANGE OF THE '64-'69 IS NOT NEARLY AS GOOD AS THE RANGE OF THE 1970 & Later Models. THE 1964-69 Collegiate five speed has a LOW GEAR(1st gear) of approx (45 GEAR), where the 1970 and later Collegiate five speed does have a LOW GEAR(1st gear) of approx (37 GEAR) which is massively better for climbing hills than the (45 GEAR) that the sixties era Collegiate has. BECAUSE THE COLLEGIATE has 26" (597mm) wheels Versus the 27" (630mm) wheels of the VARSITY-SUBURBAN-CONTINENTAL, you would have EVEN LESS HILL CLIMBING ABILITY THAN the Sixties Era Collegiate...................your LOW GEAR(1st gear) would we marginally worse than 45 GEAR because of the 26" vs 27" wheel difference if You Just Employed the Schwinn 46T front with the old model F freewheel with its largest being 28 cogs.
THE SUBURBAN was NEW for the 1970 model year. The 10 speed Suburban, the 5 speed Suburban, and 3 sp Sub (1970 & 1971 only then eliminated)
Well the ten speed Suburban is essentially a VARSITY Tourist replacement EXCEPT with the tubular front Fork from the Continental......as the ten speed Suburban has the exact same 14-28 model F gearing and 52/39 front as the Varsity and Continental does.
THE SUBURBAN five speed has the model J (japanese) 14-32 freewheel and shimano built for Schwinn rear derailleur.....the 1970 Collegiate and later HAS THE SAME EXACT model J (japanese) 14-32 freewheel and exact same shimano built for Schwinn rear derailleur. The 1970 Collegiate and 5 sp SUBURBAN marked the first for Schwinn and Shimano. PREVIOUSLY, THE EUROPEAN REAR DERAILLERS WERE UNABLE TO RELIABLY SHIFT ANYTHING IN THE THIRTY COG RANGE!! Shimano (GT-100 from 1970 through 1973 --and-- GT-120 from 1974 on) could easily do the 32 cog, THUS GIVING A MUCH MORE USEABLE, WIDER GEAR RANGE FOR THE five speeds THAT WAS NEARLY AS WIDE AS THAT OF THE EXISTING Schwinn Ten Speeds, and wider than many sixties era ten speeds!

Okay, I am not going to do all the math and chart everything here but I will let you know that the SUBURBAN five speed has a LOW GEAR (1st Gear) of 39 GEAR while the 1970 onward COLLEGIATE five speed has a LOW GEAR (1st Gear) of 37 GEAR.....................the difference is due to the 597mm versus 630mm wheels as both have the same Model J freewheel and the same 46T front crankChainwheel.
The SUBURBAN five speed has a HIGH GEAR (5th Gear) of 89 GEAR, while the 1970 onward COLLEGIATE has a HIGH GEAR (5th Gear) of 85 GEAR.....again the difference is due to the 597mm Twenty-Six VERSUS 630mm Twenty-Seven inch wheels.

I JUST SAYING THAT YOU SHOULD CONSIDER CONVERTING your Varsity TO A 5 speed, using the existing Model F 14-28 freewheel and perhaps an aftmkt (42T) front chainwheel to give you an adequate compromise of overall gearing. IT IS INCREDIBLY SIMPLE TO CHANGE Front Chainwheel ON ANY One Piece Ashtabula Crank type bicycle!!!
If you want to go with the 46T Schwinn front, THEN YOU SHOULD CHANGE TO THE 14-32 model J FREEWHEEL from the 1970 - 1976 SUBURBAN five speed --OR-- from the 1970 - 1977 COLLEGIATE five speed. ***** IF YOU DO GO WITH THE model J 14-32 freewheel, YOU WILL NEED TO SELECT A REAR DERAILLEUR WHICH CAN SHIFT The 32 Cog. The Huret Allvit of the VARSITY and 10 sp SUBURBANS & Continental WILL NOT DO THE JOB!!
The Ancient GT-100 schwinn approved made by SHIMANO will --and-- the GT-120 schwinn approved made by SHIMANO will !!

The Math that You Might Need To Do:
front SPROCKET teeth number is YOUR NUMERATOR
rear SPROCKET teeth number is YOUR DENOMINATOR

You TAKE that "result" and MULTIPLY it by the INCHES DIAMETER OF THE BICYCLE WHEEL = GEAR number

USE (27) for the INCHES DIAMETER OF THE BICYCLE WHEEL for any 27 inch(630mm) or 700C (622mm) wheel.

USE (26) for the INCHES DIAMETER OF THE BICYCLE WHEEL for any 26 inch (597mm) , (590mm)......650, 650a, 650b, 650c, or any 559mm cruiser/mtb



If you want, you can take your GEAR number and multiply that GEAR NUMBER by Pi to get Inches Travelled for Each Pedal Revolution.
GEAR number X 3.14 = Inches Travelled for Each Pedal Revolution (you do remember from 4th grade math class decades ago that Pi is 3.14)
Convert to FEET by dividing by TWELVE so that you get something more meaningful




Before you do swap gears or change things significantly, YOU SHOULD DO THE SIMPLE MATH TO SEE IF YOUR PROPOSED CHANGE WILL BE USEFUL OR DETRIMENTAL TO YOU, BECAUSE MANY FOLKS LIKE TO FLY BY THE SEAT OF THEIR PANTS, LIKE JETHRO BODINE, WITHOUT A CLUE UNTIL THEY REALIZE FROM TRIAL & ERROR.

https://www.bikeforums.net/classic-v...-derailer.html

https://www.disraeligears.co.uk/Site/...erailleur.html

(Disraeli gears site is WRONG as the GT-120 and the GT-100 both are 32 COG and not just 28 cog max as Disraeli says....those seventies Collegiates & 5 speed Suburbans Schwinns have 32 cogs and came equipped with the GT-100 (1970 thru 1973) and with the GT-120(from early 1974 onward to 1977..)

https://www.disraeligears.co.uk/Site/...erailleur.html
The Schwinn Approved GT-100 derailleur

https://www.disraeligears.co.uk/Site/...leur_D160.html

https://www.disraeligears.co.uk/Site/...2nd_style.html
https://www.bikeforums.net/classic-v...erailleur.html
https://www.bikeradar.com/us/gear/art...o-eagle-46697/

https://www.disraeligears.co.uk/Site/...leur_RS12.html

THE ABOVE ARE EXAMPLES OF OLD BASIC REAR DERAILLEURS THAT YOU CAN FIND FOR FREE OR NEXT TO NOTHING. They are HEAVY but RELIABLE AND DURABLE and function well on gas-pipe , electroforged basic 10 speeds, IF YOU'RE A CHEAPSKATE DOING IT FOR THE LOWEST CASH OUTLAY.
That Shimano RS rear derailleur is a very low end, heavy model from the early eighties that came on such the most inexpensive Sears Free Spirits circa 1983-1984 but it works well enough if in decent shape and is durable enough for for a numbskull riding an old 32+ pound bicycle.....
Most any basic NEW or used SHIMANO short cage rear derailleur will work well enough with your 14-28 cog freewheel and friction shifting. The Maeda SUNTOUR rear derailleurs of the seventies are nice choices. SUPER-LIGHTWEIGHT IS NOT YOUR FRIEND AS IT APPLIES TO REAR DERAILLEURS AND BASIC BICYCLES LIKE THE VARSITY & OTHER HEAVY GAS PIPE SLOW CRUISER 10 SPEEDS, super-light has no benefit, you want durability because lets face it, the person piloting such a heavy gas pipe Kmart 10 speed isn't going to know much about Care & Use of higher line, lightweight equipment which might not accept the same level of misuse & abuse as the more durable and heavy low line, base model derailleur. At the end of the day, someone with such an old heavy bicycle, just wants something rugged and reliable that changes the gears reliably as needed and could withstand being tossed into a cage at the zoo with the Gorilla that did all those American Tourister luggage commercials on tv back in the early seventies. For the benefit of those of you under sixty years old, that aren't familiar, the Gorilla attempted to throw and destroy the luggage. Now, maybe a Gorilla with an Ashtabula crank Schwinn bicycle, and that same Gorilla destroying something high-line and state of the art sub 20 pound bicycle would be fun to watch. We all know that the Gorillas out there should probably stick with durable and heavy equipment that can withstand a bomb blast, rather than something they would just mistreat and destroy since they have no desire to properly care for and use such quality, state of the art, high-line, equipment. CERTAINLY, THIS IS NOT SAYING THAT AN OLD SCHWINN IS BETTER THAN MODERN STATE OF THE ART BICYCLES. They are not. Not everyone needs something that you could race with in a triathlon. Some folks may be better served with cave-man simplicity and bomb blast durabilty based on both, how they ride and how they care for their bicycle. You can always have both the newest high tech ride and something ancient, and everything in between. Some simpletons probably shouldn't go too high tech, as it might be something like Mr. Magoo or Aunt Bee trying to drive a Ferrari or Maserati in a coast-to-coast Cannonball Run competition.

shelbyfv

Or you could still go with the single speed. You might ask here as to specifics https://www.bikeforums.net/singlespeed-fixed-gear/