Nathanh777

First thing is I don't know much about bikes. I have a inner tube that needs to be replaced as I want to start riding it to work and back. I've looked on youtube and other websites on how to find out which inner tube I need to replace the current one but I still am confused. I see these dimensions on the tire. 27 x 1.25. I also see 700 x 28/32c on the inner tube that is going in the trash.

fietsbob

Inner tubes are like balloons .. they will expand to fill the tire casing ,
and 27" 630*, is damned close to 622/700c..

you cannot use the tires interchangeably, but the inner tubes are interchangeable.

* Metric diameter of tire bead and rim bead seat.


to convert inches to MM . 1 inch is 25.4mm. 1.25" is like 32mm,




.....

HTupolev

27" usually refers to a tire where the bead seats at a diameter of 630mm on the rim. 27" tires aren't used on new bikes anymore, but the size is very close to 700c (bead seat diameter of 622mm). Inner tubes are pretty stretchy, and 700c inner tubes can be used just fine on 27" wheels.
1.25" is your tire width, which is roughly 32mm.

Your old inner tube is a 700c inner tube intended to 28-32mm tires, so it was probably a reasonable fit for your tires. It's also okay to get a slightly narrower tube (such a one rated for up to a 28mm tire), since again, they're stretchy.

Check whether your setup uses a presta valve or a schrader valve. Most road rims are drilled for a presta valve, but a few are schrader, which would be especially unsurprising if this is an older wheel.

Nathanh777

Can you just tell me what size to purchase? I clearly stated in my first sentence that I don't know anything about bikes. I gave all the dimensions needed.

Berg417448

If a 700 X 28/32c tube was working before then a new one of that size will still work. Just make sure you get the same valve type that the old tube had (presta vs. schrader) .

CliffordK

1.25" tire width is about 32mm width.

So, any tube that is designed for about a 32mm width tire is ok. You'll see size ranges such as the tube you had of 28mm to 32mm which is fine. Or, you could go say 32mm to 35mm.

Just get something close, you'll be ok.

As mentioned above, there are two valve types that are common (in the USA) for bicycle tubes.



Presta on the left has a little screw top. It is handy for many cyclists to put pressure in, let air out, etc. Schrader on the right is more like you'll see on cars and everything else.

Unless you chose a pump that did presta and schrader, then your pump probably supports schrader.

However, for simplicity, get whatever you have on your bike.

Many cyclists and avid commuters like to buy a couple of spare tubes, so if one should go flat, one has a spare.

expatbrit

Lazyass

One of my vintage bikes has 27 inch wheels with 1 1/4 tires. I use a 700c 28/32 tube. Bell brand from Walmart. Tubes stretch.

Retro Grouch 

I'll bet your tire really says 27 X 1 1/4. When it comes to bike tires fractions and decimals don't mean the same thing.

Find an inner tube that says either 27 X 1 1/4 or 700 X 28/32c. Chances are you'll see both numbers on the box that it comes in. The next thing to look for is the valve type. There's fat (Schrader) valves and there's skinny (Presta) valves. Pick whichever matches what you had before. That's a common size so you shouldn't have trouble finding inner tubes in either valve type.

Incidentally, my advice is to always carry a spare inner tube with you even if you don't know how to do your own replacements. If you puncture and have the proper replacement, another rider passing by may be able to help you.

rumrunn6

Walmart

Amazon

Skipjacks

Welcome to the forum. "Please" and "Thank you" go a long way.

You'll find they work better than "Hey random strangers, I demand help NOW"

cyccommute 

In terms of tubes, 700 and 27" fit the same wheel diameter. The tires on a 700C bike really aren't 700mm in diameter. They are around 650mm in diameter which is about the same 27".

Width is a bit different. That's just the diameter of the rubber part of the tire itself. 32mm width is pretty close to actually 32mm. For the metrically challenged, 1 inch is 25.4mm. So 32mm is close enough to the same as 1.25". A 27x1 1/4" tube will fit just fine in a 700x32 tire.

One note on tubes, go with a tube smaller than the tire width if you can. While a 700x25mm tube will fit in a 25mm and up tire, a 32mm tube may not fit in a 25mm tire. The tube will expand to fill the space and a smaller tube is lighter.

caloso

Take the inner tube out of the trash and take it to your local bike shop. Say "I need a new tube to replace this one." Buy several.

bobwysiwyg

Simple, direct approach.