attackontitan

Hi All,

I'm frustrated right now and by no means a bicycle guru. Several years ago I bought a cheap bicycle from a company that I believe was going out of business. I didn't want anything expensive because I knew I wouldn't ride it much. It's a single-gear bike. I assembled it myself and enjoyed it. Then after someone lost my presta valve adapter, I didn't bother to buy a new one and haven't ridden in two years. Well, now I want to ride it again.

I went to fill up the tires; the rear tire is fine, but the front one wasn't holding air. I removed the tire and tube and found a puncture, which I foolishly tried to patch with superglue; didn't work. I bought a new tube, but I failed to "measure twice and cut once"; the diameter of the new tube is slightly too big, and the presta valve is 48mm but I need 60mm because of how the wheel is designed. The old tube says 700x25/32C, and the new one I bought is 700x28/32C; it also says 27".

I searched online for tubes, and while I can find 60mm valve length, the size is listed at 28". I measured the diameter of the rim and it's 25", which seems like an odd size.

What should I do? Should I just purchase a new set of standard-sized wheels so it's easier to find replacement tubes/tires?

Thanks for any help!

P.S. Sorry I can't post photos since this is my first post. If you do a Google image search for "Create bikes fixie", that will give you a good idea of my bike.

Rolla

If the old and the new tube are both 700 and anywhere within the range of 25-32c, you’re good to go. Just get the longer valve stem. Ignore your rim measurements and any other “inch” markings. If in doubt, look at the sidewall of the tire - it’ll tell you the actual tire measurement. The tube needs to correspond with this.

attackontitan

Thanks, but I compared the old tube and the new tube, and the new tube is clearly greater in circumference. Even if the valve stem was longer, I don't see how it would fit on the wheel.

Rolla

1. Look at the size markings on the tire.
2. Look at the size markings on the tube.
3. Do they match?

• Yes = good to go
• No = get a tube that matches the tire size

attackontitan

I wish it was that simple, but something seems off. For the heck of it, I inflated the new tube fully and placed it around the rim, and it's far too big for the rim. Again, the new tube is 700x28-32, and it was purchased from a local store after showing them the old tube. I wish I could share photos.

The original tube states 700x25/32C, and right below in smaller font it says 25/32-622/630.

The tire states 25-622, and right next to it in parentheses it says 700x25C.

Then inside the rim it says 700C*18.

Rolla

It IS that simple. The tire says 700 x 25. That’s the size tube you need. An inflated tube that isn’t inside a tire will look huge. That is completely irrelevant. Put it in a tire and it won’t grow that big.

700 x 25 is the tube size you need. Stop fighting this, stop measuring things, and stop inflating tubes that aren’t mounted in a tire.

dedhed

You're overthinking it. The only thing you need to know is tire size and valve length. In this case 700x25 and 60mm
The 25-622 is the ISO (or ERTO) designation for 700x25. 700 size is 622 mm
https://www.modernbike.com/iso-sizes...tires-and-rims

https://www.walmart.com/ip/Tube-Duro...tube/165445444

​​​​​​https://www.ebay.com/p/2129873134

Daniel4

You didn't mention if you had experience changing tires and inner tubes before.

Here's a video. Skip to 1:15 where he's installing the tire. Note that he says "Partially inflate the innertube."

Outrider1

If this isn't making sense, take it to the LBS and have them fix it.

attackontitan

Okay, thanks. I'll order a new tube and try again. I had several small problems I was dealing with yesterday, but looking forward to starting a new day with a clear mind and hopefully tackling this and everything else.

chaadster

This may be a bridge too far, but you don’t need a new tube with a longer valve stem because you could get valve extenders. The extender is a simple device, but it may just be easier to just get a new tube and write the one off. Anyway, just so you know, valve extenders are an option.

prj71

Wow...That's all I can say.

timdow

your LBS will put in the right size for around $20 including the tube and labor.

Iride01 

Was the tube in the tire when you inflated it on the rim?

If not constrained by the tire, then the tube as you add air will sometimes stretch in length faster than it grows in it's cross section diameter.

If you can put the tube in the tire and it doesn't kink and wrinkle, then it should be a good enough size range. The constraints of the tire and rim will let it expand to fit what needs to be fit.

My only caveat will be that you don't want so small a tube that it stretches a lot when it's inflated inside the tire. Then it may act more like a balloon when punctured giving you a very quick flat instead of a slow leaking that gives you a tad bit of time to decide where to stop..

smd4

And don't forget to feel along the inside of the tire to remove any foreign object that may have caused your puncture in the first place. We don't want to have to go through this process a second time.

noimagination

Yes, if you inflate the tube when it is outside of the tire, it will expand in all three dimensions, and it will look "too big". Both the circumference and the "width" of the tube will look too big. The tube is designed to expand. It is elastic, it cannot fulfill it's function if it is not.

If your tire circumference is 700c and the tube says it is 700c, then the circumference is correct. Period. Forget about what you think you're seeing.

The other dimension is the width. Your tire says 25C. You need a tube that falls either between or close to this width. Your original tube says 25/32C, so it will be good for any tire with a width from 25 to 32 mm.
(Actually, the tolerances are quite a bit more (ahem) elastic than that. I personally have had no trouble (over decades of riding, for 10's of thousands of miles) using tubes labeled 25/32C in a 35mm tire, or even a 38 mm tire, for example. Similarly, if you find a tube that says 700 x 18/23C, you'll have absolutely no trouble using that tube in a 25mm tire. The limit is usually at the lower end, it can be hard to get "wider" tube into a "narrower" tire and still get the bead on. In general it is better to use a tube that is nominally a little to "narrow" for your tire than to use a tube that is nominally a little too "wide".)

The tube is designed to expand to fill the space between the wheel rim and the tire casing, and then to hold air under compression (more air is forced into the tube while it remains the same size, because the tire and rim are not elastic, thus raising the tire pressure to the desired value). That's how pneumatic tires work. The butyl that the tube is made of is elastic, it is pretty hard to get it big enough to pop it. A couple of millimeters here or there make absolutely no difference.

The width listed in the rim (18) you can ignore, unless you're trying to get really wide tires. You can use a 35mm tire on an 18mm rim without issues (that's what is on my bike). I'd check with your bike shop or with the rim manufacturer before I went too much wider than that, though.

As for the valve length, you need a valve long enough so that it extends beyond the surface of the rim enough to get the pump head on. If your old tubes had a 60mm valve, I'd stick with a valve >= 60 mm. The 60 mm valve length is pretty popular, you shouldn't have any trouble finding tubes with valves at >= 60 mm

I agree with whoever above said you're over-thinking this.

ClydeClydeson

All good advice above. Tubes stretch when filled with air, so will appear too big if you inflate it outside the tire. For fun, you can inflate a tube to be much bigger than the wheel as an experiment before you put it in the tire... much MUCH bigger. If you go to far it will burst, though, and make a loud noise. For extra credit, take a damaged tube and tie a knot in it to isolate the hole from the valve and re-inflate until it bursts, then tie another knot and inflate again!

Anyhoo, you can likely fit whatever tube you have into your tire. Let all the air out and the tube will be just about a perfect fit for the inside of the tire, and will stretch to fill it when you inflate.

PS. 27" tires are very close in size to 700C tires, and since tubes can stretch a lot, 27" and 700C tubes are generally interchangeable. Not the tires, but the tubes can absolutely be used in either.

Also, 28" is another way 700C tires are labelled, primarily in Europe.

rekmeyata

The easiest way is that you could have taken the old tube down to the store and they would have matched it for you, including the right size and right length of valve stem.