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Old 06-02-2020, 12:19 AM
drgonzo drgonzo is online now
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Tubes for 28mm?

I’m about to start running 28’s on my bike for the first time and noticed all the tubes I have are spec’d for 19-25mm. Also most of the tubes I see for sale online are for 19-25mm. How important is the tube sizing? What do you guys run in your 28s? Thanks!
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Old 06-02-2020, 12:28 AM
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choke choke is offline
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The 19-25 tubes should be fine. I have been using that size in 32-35mm tires for years with no problems.
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Old 06-02-2020, 12:55 AM
drgonzo drgonzo is online now
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Quote:
Originally Posted by choke View Post
The 19-25 tubes should be fine. I have been using that size in 32-35mm tires for years with no problems.
I was thinking that was the case but figured I’d play it safe and ask first. Thanks!
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Old 06-02-2020, 01:14 AM
cyan cyan is offline
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If you plan to run latex, it may be better to run tubes closer to the tire size, at least that's what I've been told by Vittoria.
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Old 06-02-2020, 01:28 AM
dddd dddd is offline
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When you get even a tiny puncture in a tube that is highly stretched, the rate of air loss is going to be much higher than when the tube is only stretching slightly to fill the volume inside of the tire.

And near the valve stem, those skinny tubes will have only half of the circumference of the tube doing all of the stretching, since the thicker rubber pad around the base of the stem hardly stretches at all.

It gets much worse if the wide tire is mounted on a narrow rim, since the skinny tube inflates hard inside of the tire only, and pins itself inside of the tire by air pressure before narrow portion facing the rim cavity then has to stretch heavily to fill the rim cavity. Expect tube ruptures to either side of the stem reinforcement where the reinforcement will be especially resistant to falling between the tires beads (which are going to be only about 10mm apart).
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Old 06-02-2020, 07:00 AM
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oldpotatoe oldpotatoe is offline
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Quote:
Originally Posted by dddd View Post
When you get even a tiny puncture in a tube that is highly stretched, the rate of air loss is going to be much higher than when the tube is only stretching slightly to fill the volume inside of the tire.

And near the valve stem, those skinny tubes will have only half of the circumference of the tube doing all of the stretching, since the thicker rubber pad around the base of the stem hardly stretches at all.

It gets much worse if the wide tire is mounted on a narrow rim, since the skinny tube inflates hard inside of the tire only, and pins itself inside of the tire by air pressure before narrow portion facing the rim cavity then has to stretch heavily to fill the rim cavity. Expect tube ruptures to either side of the stem reinforcement where the reinforcement will be especially resistant to falling between the tires beads (which are going to be only about 10mm apart).
True but the OP is going to use a 25mm tube in a 28mm tire..not 'highly stretched'. 25mm tube will be fine..
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Old 06-02-2020, 07:06 AM
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saab2000 saab2000 is offline
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I use Michelin 21-25mm tubes in some 28mm tires and I was nervous at first as well but have experienced no issues at all.

Try inflating a tube outside a tire and you'll see how enormous they get before they burst. You should have no problems.

FWIW, if you do this, wear ear and eye protection. When they burst it's like a Howitzer being fired!
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Old 06-02-2020, 08:26 AM
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Davist Davist is offline
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yeah, I use 21-25mm in 28s up to 32s.. to be honest there's more variance, as we all know, in tire sizes than nominal would indicate. I've had Schwalbe 25s wider than continental 28s etc..
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Old 06-02-2020, 08:48 AM
GregL GregL is offline
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My "go to" presta valve tubes are Specialized in size 20-28mm. They cover a wide range of road tire sizes and have proven to be well-made and durable. https://www.specialized.com/us/en/st...Text=030-01302

Greg
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Old 06-02-2020, 08:54 AM
palincss palincss is offline
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Everyone so far has viewed this from the perspective of stretching a too-small tube too much. But consider it from the opposite perspective for a moment. A tube that is too large is hard to install, tending to get caught under the bead of the tire - a recipe for an on-the-road blowout. I'd rather use a tube that is slightly too small than one slightly too large. Stretching a tube from 25 to 28mm (not much of a stretch) is IMHO better than trying to cram a 32mm tube into 28mm.
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Old 06-02-2020, 09:34 AM
benb benb is offline
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I don't think either of these too small/too large variations are really an issue unless you're constantly getting flats for some other reason.

In any case I have run lots of tires in this range and I've never had any issue or had to do any work to find tubes that are optimal fit.

Bontrager, Specialized, Giant, IIRC they all have tubes that cover this range and nearly every LBS has one of those brands & every time I need a tube any LBS I walk in has one that fits right. Usually it's a 700x28-32c size.

No need to overthink and try to get a boutique tube, just go get a tube from the LBS and be done with it.
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Old 06-02-2020, 09:43 AM
arimajol arimajol is offline
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Quote:
Originally Posted by palincss View Post
Everyone so far has viewed this from the perspective of stretching a too-small tube too much. But consider it from the opposite perspective for a moment. A tube that is too large is hard to install, tending to get caught under the bead of the tire - a recipe for an on-the-road blowout. I'd rather use a tube that is slightly too small than one slightly too large. Stretching a tube from 25 to 28mm (not much of a stretch) is IMHO better than trying to cram a 32mm tube into 28mm.
+1. I use the smaller tubes. I have tried the larger ones, but i couldn't get tires to seat properly.
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  #13  
Old 06-02-2020, 12:15 PM
drgonzo drgonzo is online now
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Quote:
Originally Posted by benb View Post
I don't think either of these too small/too large variations are really an issue unless you're constantly getting flats for some other reason.

In any case I have run lots of tires in this range and I've never had any issue or had to do any work to find tubes that are optimal fit.

Bontrager, Specialized, Giant, IIRC they all have tubes that cover this range and nearly every LBS has one of those brands & every time I need a tube any LBS I walk in has one that fits right. Usually it's a 700x28-32c size.

No need to overthink and try to get a boutique tube, just go get a tube from the LBS and be done with it.
Pretty much my mode of operation for nearly all things bike related. thanks!
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  #14  
Old 06-02-2020, 12:35 PM
OldCrank OldCrank is offline
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I put some Conti 25-32s in my Michelin 28s (yeah they run big). No more probs than the usual Contis.

$7 at mybikeshop.com, $5.50 at ProBikeKit, even cheaper on eBay.
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  #15  
Old 06-02-2020, 02:10 PM
picstloup picstloup is offline
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Quote:
Originally Posted by oldpotatoe View Post
True but the OP is going to use a 25mm tube in a 28mm tire..not 'highly stretched'. 25mm tube will be fine..
i'd agree with this cause of personal experience...

years ago I used vittoria tires, 23mm corsa opens or something with latex tubes, i think they were michelin and maybe 19-23...when I'd used up the tire and tried to use the tube again they were always too big, stretched out, near impossible to fit back into a 23mm tire...

just bought some conti grand prix 5000s, 25mm, and ordered michelin 22-23 size air comp latex...actually, they look crazy wide in the box compared to butyl tubes of the same size...i don't think i'd hesitate to put them in 28mm tires...just my opinion...i'm no expert, no mechanic...i think i'm gonna start em out very low pressure, and work up a bit...i usually ride at 6.5 to 7 bars up front...just start at 6.5, maybe 7 in the rear...see how it feels...

the butyl conti's have 25-32 stamped on the tubes themselves...
the latex michelin's are what is marked on the box...i wouldn't hesitate to use 'em in my 28mm tires...




200602.tubes-0004418
by Morris, on Flickr



200602.tubeboxes-0004419
by Morris, on Flickr

Last edited by picstloup; 06-02-2020 at 03:43 PM.
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