Inner tube for 700c beater

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MrQuackers

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I have an old 90s Giant Farrago and it has 700c Schrader rims. Finding that tube is like hunting for hen's teeth. Is a 27x1.25 tube compatible? Tires are 700c x 35
 
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700 & 27 tubes are interchangeable but not the tires. 1.25 would be about right, worse case, stretches a little bit more inside the tire.I

You can buy inserts to convert Schraeder to Presta essentially they are O rings.
 
Check out this Wiki article on bicycle wheel sizing:

https://en.wikipedia.org/wiki/Bicycle_wheel#700C_road_bicycle_wheels_/_ISO_622_mm

700C and 29"ers use the same rim diameter - 622 mm. Typically you can go from a smaller nominal tube size to a larger nominal tire size, but not vice versa. E.g. Your 35 mm tire is about 1-3/8". You could use a smaller (for example, 1-1/4", tube in a 35 mm tire), but I would not use a 2" tube in a 35 mm tire.)

I'm not sure about 27" - it seems that the nominal sizes (700 mm, 26", and 29") pertain to the approximate O.D. of the wheel and tire assembly when a typical tire is fit to the rim. It seems to me that a 27" rim/tire combination is part of the 622 mm rim family, running a fairly skinny tire.

Examples:

A 26" mountain bike tire is typically around 2" in cross-section. A 26" rim is 559 mm (22") in diameter. 22" + 2(2") = 26". But if you went with a 1.5" tire, the O.D. would drop to 25". If you went with a 2.375" tire, the O.D. would be 26.75". So, the nominal 26" is an approximation.

A 29" mountain bike tire is typically around 2.2" in cross-section. A 29" rim is 622 mm (close to 24.5") in diameter. 24.5" + 2(2.2") = 28.9". If you ran a 1.5" tire instead, you'd be down around 27.5" O.D. If you went with a 2.7" tire, you'd be up at 29.9". So again, 29" is an approximation.

So in every case, the nominal wheel/tire combination's O.D. will vary in real life depending on tire size.

A "700 mm wheel" (the nominal size of a 622 mm wheel with a 39 mm tire installed) will be more or less depending on which tire is installed. 622 mm (actual rim diameter) + 2(35 mm) = 692 mm = 27.2". I would be that's what you've got.

For what it's worth, the Schwalbe Marathon tires on my Kona Dew Deluxe say "622 x 32/28" x 1-1/4"/700C x 32". I'd think that you'd be fine with any Schrader-valve equipped tube identified for use with 622 mm/700C/28" wheels for a nominal tire size of no less than 32 mm/1.25".

Bike experts, please jump in! I may have this wrong.
 
Originally Posted by MrQuackers
I have an old 90s Giant Farrago and it has 700c Schrader rims. Finding that tube is like hunting for hen's teeth. Is a 27x1.25 tube compatible? Tires are 700c x 35


They are readily available on Amazon all day long:

700c Inner Tubes
 
Don't get the 'lite' which have thin walls and as lite as possible, they are pretty fragile.
 
Originally Posted by AZjeff
Convert them to Presta and be done with it. 700C/Schrader is just kinda wrong.



That's funny and true. I built my mom a bike a few years back and I did Schraeder/700c only because I knew it would be easier for her. It pained me to drill those rims.
 
Thank you for the replies
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GiantFarrago.jpg
 
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IMHO, any beater in the USA should use Schrader valves so you can just fill up wherever and find spare tubes in Walmart. To me a "beater" is a bike that gets next to no maintenance and can be parked anywhere in any weather, and when it does need work parts are available at any bargain store. YMMV.
 
A 700c schrader tube is hardly a unicorn. Check any bike shop, Amazon, Nashbar, Jenson, etc. And yes, 700c/27in tubes are interchangable (unlike tires!).
 
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