Murrays

I was putting new, longer stemmed tubes on our tandem and noticed they were sized for 700 x 20-25mm tires. We are running Conti 28mm wide tires.

Any thoughts on the mismatch? Are we stretching our luck here (pun intended)?

-murray

masiman

You can run them but they may not last as long. I had something similar in mine but did not know it until I flatted. I put in the appropriate sized tubes and rode on.

cornucopia72

Not by choice, but we have done the same thing with no noticeable difference that we could tell.

zonatandem

Should not be an issue, except when changing tubes it'll be a bit easier to stuff tube in tire due to smaller circumference of tube.

zonatandem

Should not be an issue, except when changing tubes it'll be a bit easier to stuff tube in tire due to smaller circumference of tube.

aggie_grad

I have had to do the same thing on my tandem due to the deep aero wheels (race-lites). It is difficult to find long valve stem tubes that go above 25 mm. I have not had any trouble running them for a couple of years.

Aggie_grad

rmac

The only problem that we have had with narrower tubes in 28 tires is with ultra-lite tubes. Even though they were marked to go up to 26, within a very short time they would develop a leak around the valve hole. I guess they just became too thin with the extra stretching.

Old Hammer Boy

I've been using a bit smaller tubes for some time without problems (19 X 26c tubes on 28c tires). Some tires are smaller than specified anyway, especially older Panaracers. It seems I have fewer pinch flats this way, and haven't had the valve cut problem mentioned above either. Works for me.

zonatandem

Recently had a Presta valve break loose from the actual inner tube on single bike. Checked for burr by valve hole in rim, but found nothing. Resorted to old trick: cut small piece off old tube ('bout 1" square), cut a hole dead center of that; then slip it over the valve stem, thereby giving that area a bit thicker
protection. Seems to work . . . or maybe it was just a faulty inndertube.
The x-tra lite tubes that are sizes too small will stretch a bit too far and can create problems. Tubeless tires could be the answer.

Old Hammer Boy

Great suggestion Rudy. Nothing like experience, is there?

steveh2

Maybe someone can answer this for me.

I just bought new tires, sized 700x23C or 23-622. Vittoria Rubino something-or-others, for a standard road bike. I asked for some new tubes to go with, and the guy at the LBS gave me Bontrager tubes sized 700/31-38. (I previously was using 700/18-25 tubes with 700x25c tires.)

When I inserted the new tube, it was too long for the circumference of the tire, so that there was some bunching or overlap when it was all pushed in. But I was able to inflate the tire (very slowly) up to 110 psi, it held pressure for two days, and I rode it this morning just fine.

Am I okay with this tube size, or would I be better off going with the 700/18-25?

(FWIW, I read Sheldon Brown's oft-cited article on tires and tubes at length. It has a lot of information regarding tire sizes, but almost nothing on tube sizes.)

masiman

I have run tires that way before but they ended up failing shortly. If I remember, one ended up unseating the tire at the point where the inner tube was bunched.

Inner tubes are quite forgiving but if too small you will increase the chance of pinching during installation, too large and you can get bumps in the tire surface, tire blowout or inner tube blowout. Not gauranteed these will happen but increased risk.

If you continue on it, make sure you take at least a spare inner tube. I'd also take a folding tire just in case.

I think that tire was way too big for what you have. He did not look carefully, did not have the right size in stock or did not care.

cornucopia72

I would take the tubes back to LBS and get the right size tube or my money back. Why would someone recommend a tube that is too large? It is heavier, harder to install, and risky too.

cornucopia72

I would take the tubes back to LBS and get the right size tube or my money back. Why would someone recommend a tube that is too large? It is heavier, harder to install, and risky too.

zzzwillzzz

probably not, as i have mich pro2 700x25 on the tandem and we've been getting a lot of pinch flats recently. i thought i'd take off the michelins and put on the conti 2000s that are 700x28 but those were smaller than the mich 700x25. i also had a said of old avocet 700x28s, those were smaller than the michelins also. i think you will be fine with those tubes, unless your 28 are much larger, which i doubt since one of my sets of 28s is by continental

CBBaron

I've run one size smaller and one size bigger tubes in my tires without much problems, just make sure you get the bigger tubes installed without pinches or folds. The extra large tube may work but if you have a fold it will wear out quick at that point. You maybe able to get it installed correctly but I don't think its worth the effort.
Using the correct sized tube ensures you have a good amount of rubber without being too difficult to install.

Craig

2372ighost

I just bought two new Specialized tubes, box marked "Long stem presta valve 700x20/28c

Mister W

A friend blew out a rear tyre on their tandem because he was using too large an inner tube. Fortunately he was able to control and stop the bike without the tyre coming off the rim completely. If it had been a front tyre I doubt they'd have stayed upright.

Stick with correct sized tubes!

TandemGeek

Did the tire blow because the tube was larger than specified or because during the tire mounting process a portion of the tube became pinched between the tire and rim, then subsequently blew?

I don't necessarily disagree that you should try to use the correct diameter range of tubes for a given tire as it eliminates mounting issues. However, there is a lot of margin for error in freely vulcanised or vulcanised in-mould butyl tubes so long as you take care in mounting them. Please note that inner tubes should not be inflated beyond a few lbs of air outside of a tire casing as it will deform the tube, even more so with latex tubes (which probably shouldn't be used on tandems anyway).

In short: If you can get a tube that will hold air to fit in a tire casing without folding (partial inflation usually takes care of that) and fit it to a rim without getting it pinched between the tire's bead and the rim, it will work just fine.

mrfish

Having too small a tube in your tyre isn't a problem at all for road biking. Tubes will easily stretch to far larger than their original size. The only change will be that the tube wall will be proportionally thinner. This is only a bad thing if you're riding offroad and get snakebite flats.

Many road riders (myself included) pay extra to get lightweight inner tubes such as Conti Supersonics as road bikes don't get pinch flats if the tyre is correctly inflated for the weight it's carrying. On a tandem in my opinion this can often mean inflating the tyre more than the manufacturer's recommended psi. See previous discussions on this as this has been covered many times.

Echoing Mark, Using a tube that's so big you need to fold it to get it all in though is probably a bad idea, not least because part of the tyre probably won't inflate. However I'm pretty sure you could ride a 700c tube inside an wide MTB tyre in emergency. Not something I plan to try though!

Andrew

pujark

Hi Everyone,
I have bought a new road bike. It's tube size is 700*28C. I got it ordered online and the rare tube came punctured. So I had to buy new tube. New tube size is 700*28-32C. I think it's minimum 28 and max is 32. Now when I m filling up the air, my tire doesn't go tight.
I have never used such flexible size tube - I am not sure what to do. no matter how much air I fill in - the tire just doesnt get tight and I can not ride the bike I have observed other bikes on the road but they all have tight tires. I know it's silly question but I am very confused now.
Could anyone please tell me - is there something wrong with my tube? or as the tube is bigger the tire will never get tight? or should I buy the new tube with exact size?
Thanks for your time
Kiran

WheresWaldo

Wow, resurrecting a three year old thread to ask a question. Anyway, as long as you have adequate tire pressure it won't really matter that the tube is a hair on the big side. Get a pressure gauge as "tight" is too subjective to use as an indicator of proper inflation, neither is using a calibrated thumb and forefinger.

pujark

Thanks for your swift reply. Currently I don't have meter to check the pressure but I will buy one.