I run 25mm tires, would I be better with 20-25mm tubes or 25-32mm tubes?

thanks

A little more tube material should help resist punctures, a litle less tube material should weigh less, roll more efficiently, and be better for performance, but who knows if the marginal differences are meaningful for your riding or tastes. My suggestion would be to go with the smaller tube and let your tire take care of the foreign object intrusion issue.

The bigger tubes would be harder to install.

The posts above pretty much sums it up. Bigger will stretch the tube less and make it (minimally) less prone to punctures. Smaller will be easier to install since it won't bunch up or take up as much space before inflating. Personally, I prefer the 20-25 but have used a 25-32 without issue.

I second that. In my 25 mm Continental GP5K and GP (which measure < 1" inflated on a 17 mm internal width wheel) I install Michelin 18-25c tubes:

Amazon.com : Michelin A1 Airstop 700x18-25c Road Bike Tube Bundle 52mm Smooth Presta - 4 PACK : Sports & Outdoors

Smaller tubes every time. Less chance of popping them if you're mounting a tire with a tight bead and less chance of a pinch flat when riding. I just installed 27mm tires with a 18-23 tube. The tire is a Challenge Paris Roubaix open tubular with super tight beads. I popped an 25-28 tube three times and gave up. Got some 18-23's and they went in no problem.

A bigger tube also will lose pressure slightly more slowly.

It depends.

If the larger tube fit well in my tire without appearing to wrinkle or kink then I'd probably go with that. As terrymorse said it'll lose air more slowly when punctured generally, not every time. But on the other side of that, a smaller tube that is stretched to fill up the inside of the tire is going to behave more like a balloon being stuck with a pin when punctured.

When I had my last flat I was able to ride the bike home for five or six miles as the leak was slow so I just kept topping it off with air a couple times. Changing a flat in the comfort of AC is more desirable than changing a flat in 90°F and 90% humidity.

I Tried Both. Went with The Smaller size.

Thanks, went with the small range.

I run Continental 26" downhill tubes that are for 2.3" to 2.7" wide tires in my Schwalbe 26"X2" tires. There is very little drop in pressure over several weeks. By using the largest tube that will fit I have had no internal flats.

The lower is the tire pressure, the slower is the pressure drop, so this has probably very little to do with oversized tubes - MTB pressure is just low to start. What are "internal flats"?

I use 25-32 in my 25’s. They a little more of a pain to install, but I went that way for less stretch. I have a couple bikes with 28mm tires and so the one size fits all, (of my stuff), makes it pretty easy.

John

19-25 were the standard tube size when I ran skinny 20mm and can’t recall the tube being too big.

Maybe one day we will learn that 700x18-25 tubes are exactly the same thing as 700x23-28 tubes, just like two week contact lenses are the same as daily disposable contact lenses.

A first world problem. Back in the olden days there were 700c / 27" tubes and 26" tubes. Life was simpler back then and most people were easily pleased with either one or the other.

Today there are a plethora of choices - marginally different sizes, different thicknesses, valve stem lengths etc. Bike shop owners must hate it because there are so many different ones that they never seem to have the exact tube that I want in stock.

Personally, I've become an internet buyer because I can order the exact inner tube configuration that I want. The drawback is I have to inventory my own stock of spares.

This inspired me to run to my garage and snap a pic. You be the judge.

I prefer 6L6 tubes in my tires but the glass breaks pretty easily.

Are they both brand new and never been inflated before? And why do they have so many seams?

Never inflated, but to be fair I have no idea if they are the same brand (or at least same factory). It has been a long time since I took those out of their boxes and put them in their respective bikes' seat bags. Their stems look identical, but that's all I can tell.

those that are smaller will be easier to install

I like it. But at my age I would have walked, not run and in my case it is the basement as the detached garage is not secure enough for bike storage.

I believe he is referring to pinch flats. Stuffing the larger tube stands a chance of the tube getting pinched between the tire and rim.

That being said, I have 32 tubes inside my 25 tires but I'm always very careful to avoid pinching the tubes in the bead seat and haven't had a pinch flat since I learned to mount my own tires as a kid. And at my age, that is a long time.

Are they "tubes" or "valves"?

Those aren't seams. Those are lines in the curing mould:



inner tube curing mould

They're tubes where I'm from.