jeb814

I'm rebuilding a Free Spirit. Component mix suggests a bike from the 70's. I just tried to mount 26" tires on the rims and there is no way that a 26" is going to fit this rim. 27" tires are way too big. I just measured another bike that is fit with 26" tires and found the rim diameter to be a little under 23". A rim on which a 27" tire fits has a diameter of a little over 25". The steel rims from the Free Spirit are 24" in diameter. What am I looking at here?

There is an older thread about Free Spirits. On that thread someone mentioned that Sears purchased their bikes from multiple manufacturers, and that there were some "odd" size rims. Is this what I am looking at? Or, am I missing something else.

Unfortunately the tires and tubes from this bike have long been trashed and are not available for reference. The steel rims have cleaned up nicely and I'd like to use them. What tire size? https://www.bikeforums.net/images/smilies/cry.gif

Bianchigirll 

Are you trying to mount 26x1.5 tires? (Typical MTB size tire), they most likely are 26x1 3/8. also I think there is a weird 26" schwinn size.

Happy Valley?? Like Goose Bay?

wahoonc

What type of bike is it? If it is a 3 speed (or was) chances are good it is a 26x1-3/8" aka 590mm versus the 26x1.5 which would be a 559mm. Those are two of the most common sizes. You also have Schwinn S-6 which is 597mm. Sheldon Brown has a good article on tire sizing.

Aaron

Jeff Wills

Ditto. A 70's-era Free Spirit probably has 26 x 1 3/8 (EA3) rims and tires. The only way you're going to find out (since the old tires and tubes are gone) is by trying them on. Take a wheel to a well-equipped bike store and work through the "odd 26-inch tire" stock.

jeb814

This is a ladies 10 speed with drop handlebars. I checked Sheldon Brown's site but couldn't find an answer to my particular riddle. There were two types of 26" tires that I tried to mount. One set came from a recumbent (26 X 1.75 47 - 559) and one set were new (26 X 1.95 50 - 559). I am probably showing my ignorance here, but the issue does not seem to be with the width of the tire. If the tires fit perfectly on a rim with a diameter of 23", how can they fit on a rim that is 24"? There simply is not enough "stretch" in the tire to mount them.

clubman 

Try this one. Tale a tailors tape and measure around the rim for the bead seat circumference and compare with Rim chart. It won't show you 559's but you've ruled it out anyway

BluesDaddy

A tire with a decimal in the width will not fit your rims. That is ISO size 559 which is for 26" MTBs. You want a fractional width like 26X1-3/8" which would be ISO 590.

Jeff Wills

Stop thinking that the marked tire size has anything to do with the physical measurement of the rim. That's your first error.

You've established that 26-inch "mountain bike" size tires don't fit (these have a bead seat diameter of 559mm- and the two you tried are interchangeable). The rims that were standard equipment on a '70's Free Spirit were probably 26 x 1 3/8 (EA3), with a bead seat diameter of 590mm, so it makes sense that they're roughly an inch larger in diameter.

There are about 6 different non-interchangeable "26-inch" bicycle tires. It's a long, long, story, best expressed in Sheldon's article: https://sheldonbrown.com/tire-sizing.html

jeb814

Bingo. That's what I needed to hear. Thanks for the bold print. I didn't have a clue. Time for cognitive readjustment!

Bianchigirll 

What am I like chopped liver?

To paraphrase the words of barbra Billingsly "Chump don't want my help chump ain't gonna get no help"!

https://www.funnyordie.com/videos/52051ec56f/airplane-oh-stewardess-i-speak-jive-from-dirttron

hueyhoolihan

i remember that clip from Airplane!

half way through the video i began wondering if i somehow missed Barbara.

nice to see her again. thanks.

clubman 

ROTFLMAO Timing is everything. Thanks

krome

Unfortunately, the bicycle predates the metric system. Don't trust inch sizing, always look at the metric specification on the tire, it is unambiguous. If there is no metric size listed on the tire, then you must use the inch size listed verbatim. Decimal tire sizes do not equate to fractional sizes, even if they are mathematically equivalent.

I wish the metric system was invented 100 years earlier. It would have saved us much grief.

Bianchigirll 

Clubman do you have that chart in a larger file? would you mind emailing it to me? Might be good to have around.

wahoonc

Nah you would still have some hold outs... I work heavy construction, most blue prints are still done in Imperial measurements...notable exception, government projects on military bases, most if not all of those are metric...go figure.

Aaron

clubman 

Is this big enough? Otherwise I will send.

Bianchigirll 

Sure does thanks!!

Jeff Wills

With circumference dimensions down to the hundredths of an inch. Blorp! My brain just exploded.

jeb814

Ouch. No disrespect meant by not responding to your initial post. I was too dense to understand the concept until you all repeated it a couple of times in different formats. I appreciate everyone's help.

brianinc-ville

No

Actually, it was -- the metric system was one of the more successful products of the French revolution, developed in the early 1790s and officially adopted in 1799, more than half a century before the penny-farthing was invented. But even in France, the metric system didn't help -- they still decided to measure by the outside diameter of the tire (which is pretty variable), rather than the bead seat diameter of the rim (which isn't) -- hence, the difference between 650A and 650B, 700B and 700C, etc. Why it took so long for people to figure out that it's easier to measure by the rim, I've got no idea. Does anybody know why it was?

k_as_in_knife

It depends on what problem you're trying to solve. If you're trying to fit wheels into a frame, then the outside diameter is what you need to know - and this the way the manufacturer will approach it, because they're designing the frame with a certain wheel size in mind (overall size including the tire). That, plus the tire width, determines the rim size that will work.

For those of us trying to find replacement tires for an existing rim, well, then bead-seat diameter is the critical measurement. The real problem is that until the ISO standard was established, everybody just used whatever nomenclature they liked - usually something that reflected the overall diameter, because that's how the bikes were marketed, for the most part.

seedsbelize 

When you find out what it is, please post it here. I have a set of the same rims, and threw the tires away before I realized... One of mine is stamped 26 x 1 3/something. It looks like a 1, but that, of course, can't be. Mine are from a '79 Free Spirit.

Bianchigirll 

I suspected as much but I just had to get a dig in at your expense

krome

Do'h You're right. History brain fart. Hopefully one day we'll settle down to one system of measurement. Then we'll encounter extra-terrestrials and have another system to deal with.

Jeff Wills

See above. Oh, what the hell...

"The rims that were standard equipment on a '70's Free Spirit were probably 26 x 1 3/8 (EA3), with a bead seat diameter of 590mm"

These tires are available through many bike shops and also through discount retailers- Walmart and the like. The Schwinn size (26 x 1 3/8" (S-6)) is much harder to find.