Commuting - Finally got a spare tube to carry while riding

Is my LBS shooting me BS?

My tires/tubes are 700C x 28's and the guy behind the counter throws me a 700C x 23-25 tube and says that 3mm shouldn't make a difference.
They don't carry size 28 with Presta valve, should I find some other place to pick up the right tube? or is he correct in saying that 3mm don't matter?

Your LBS is shootin' ya straight.
23/25's will be fine.

Is my LBS shooting me BS?

My tires/tubes are 700C x 28's and the guy behind the counter throws me a 700C x 23-25 tube and says that 3mm shouldn't make a difference.
They don't carry size 28 with Presta valve, should I find some other place to pick up the right tube? or is he correct in saying that 3mm don't matter?

Actually, your lbs was doing you a favor. All my 'emergency tubes' are undersized. My tires/tubes are 28mm as well. My replacement tubes are 18-25mm. Much easier to work with in a roadside situation. I save the original tube, patch it when I get home and deflate the emergency tube and swap them out. Much less opportunity to get a pinch flat w/smaller tubes while installing them. That's been MY experience, anyway. Also, I carry a patch kit for fail/safe commuting.

The inner tube never gets to expand to it's unconstricted size (e.g. outside of the tire) when in service. So long as the diameter and valve is compatible, you should be okay.


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Your LBS is correct.

A lot of times the size on the box will be different than what the factory marked on the tube, also, to make things more confusing. As long as it's in the ballpark, you're good.

My LBS never has 700x28 in stock. Always buy 700x23-25. They stretch. Its fine.

Yep, all mine are a bit undersized, too.

You can even use a 26" tube in a 29er tire.

Yep, all mine are a bit undersized, too.

You can even use a 26" tube in a 29er tire.

Right....

ThanX alot folks. :thumb:

I only wondered because the first tube I bought. He asked what size, I say 700 x 28. then he asks Schreader or Presta? and outta habit I say Scheader. :innocent:
I get home and realize I needed Presta valve. :crash: The funny thing was the scheader valve was 700 x 28.. go figure.:twitchy:

Do slightly larger tubes work fine as well?

One size up or down should be fine. :)

If you have the choice of a size too big or a size too small, take the small one. A tube that isn't stretched out as far as it's meant to be will increase your rolling resistance, and bigger tubes weigh more anyway.

Right....

You can.

To the OP:
We stock all possible sizes, but for a spare, I usually recommend that the customer carry a 700x19-23 tube (if they have a larger size) due to the lack of space in most seat bags. Also, as mentioned, much easier to install on the side of the road. Lighter, too, so you get the benefit of a laytex tube without the cost or penchant for flats. (partially tongue-in-cheek on that one).

You are going to die. Sorry.

More important the tube size is valve length. Deep section rims need longer valves. You put long valves in box-section rims but they stick out a lot and the extra leverage means they are more vulnerable to damage from aggressive pumping.
Short-valve, medium-sized tubes are very hard to find anywhere.

You can.


Do enlighten me how a 26' tube will fit in a 29er wheel... There's ~60mm diameter difference.

Do enlighten me how a 26' tube will fit in a 29er wheel... There's ~60mm diameter difference.

If you have a loose 26" tube sitting around, pump it up and take note of how large it gets. FWIW, one can even get a 20" bmx tube to fit on a 26" rim! (to make ghetto tubeless setup, for example).

Do enlighten me how a 26' tube will fit in a 29er wheel... There's ~60mm diameter difference.

Rubber stretches.

You are good to go. Many people prefer tubes one size too small because they are easier to install without pinching the tube between the rim and the time. I recently found out that the mechanic at my LBS runs tubes TWO sizes too small.

You can also use a 700c tube in a 650 wheel in a pinch. I've seen it done and it worked very well for the rest of the ride.

Good thread, I'm thinking of trying 23mm latex road tubes in my 35mm cross tires for this seasons races. It's impossible to find good, light, tubes for cross. All the cool kids run tubulars. :)

Along with the tube, I suggest a tire-change tool, simple patch kit, etc. I have all the items in a tube box, sandwiched in with the tube. Do be careful when putting all the bits into the tube box, though, as you might damage the tube if you just jam everything in.

I've had mixed luck with the peel off type of patches. Some last, some leak. But peel off patch kits are so small, easy to use, easy to carry. So I use them if I get a flat on a ride. But if a tire goes flat after a ride, I usually chuck the tube and replace with a new tube.

I've had mixed luck with the peel off type of patches. Some last, some leak. But peel off patch kits are so small, easy to use, easy to carry. So I use them if I get a flat on a ride. But if a tire goes flat after a ride, I usually chuck the tube and replace with a new tube.

They're great but they don't become part of the tube like a regular patch with glue, so it will eventually fall / wear off.

Most of time it works out fine for me; however, I had a weird flat using an undersized tube (18-23 tube in a 28 tire) where the puncture was on the side facing the rim. The tube had permanently ballooned out into into the recesses where rim tape ran over the spoke holes (like a bunch of little aneurysms) and one resulted in a puncture. I'd never seen that happen before. There were no sharp edges at the hole of interest and I put baby powder on the tube before installation to avoid sticking. Its only an N of 1 so you can't read too much into it. Maybe it was just a bad tube that also happened to be undersized.

On a related note, I wonder how well patched undersize tubes perform. Since the undersized tube needs to expand more to fill the larger tube, but the patch doesn't really expand much at all, are you putting an unsafe strain on the tube in the region of the patch?