Looking for an odd sized tube
#1
Twincities MN
Thread Starter
Looking for an odd sized tube
I went to my LBS in search of tubes for a 32-507 tire. This is a Kenda SB8 also marked 24 x 1.125. The guys couldn't figure it out. The closest I can find on the Schwalbe site is the SV 9. It fits the following:
47-507
28-540
37-540
28-541
37-541
24 x 1.75
24 x 1 1/8
24 x 1 3/8
Can anyone help me?
47-507
28-540
37-540
28-541
37-541
24 x 1.75
24 x 1 1/8
24 x 1 3/8
Can anyone help me?
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#2
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If it were my bike, I'd be tempted to see if an AV8/SV8 would stretch enough on the inside circumference to work. Since all of the 507 options are "big", make sure you put some air into the tube before installing the second bead.
#3
Twincities MN
Thread Starter
Is there a downside to stretching the tube? The kid is maybe 60lbs. Maybe. So lower psi.
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#4
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Not really, provided it's not too extreme. Consider that it stretches plenty in the "outward" direction.
#5
Twincities MN
Thread Starter
Ah good point.
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#6
Senior Member
Stretching a tube a bit is better than folding a tube into a space. I have pulled out tubes that were too big that had abraded on themselves and lost air.
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As a rule it's better to stretch an undersized tube, than try to stuff in a fat one. But when the wheel diameter (not width) is under it can make mounting a pain, because the tube will pull down below the unmounted part of the tire increasing the chances of pinching it.
Also consider that tube sizing is a very approximate thing, and there's little close correlation between what's written on the box, and the tube inside.
One place you might try is Terry Precision bicycles. They use (used to use?) a high performance narrow 24" wheel on some of their bikes. I believe it's something fairly close to a 25-520 (aka 24x1), and the tube could be a very good fit for you. Going slightly long on the wheel diameter, won't make it hard to stuff, and can even help because with a bit of air it'll position itself deeper into the tire and stay away from the bead, lessening the chance of pinching.
Also consider that tube sizing is a very approximate thing, and there's little close correlation between what's written on the box, and the tube inside.
One place you might try is Terry Precision bicycles. They use (used to use?) a high performance narrow 24" wheel on some of their bikes. I believe it's something fairly close to a 25-520 (aka 24x1), and the tube could be a very good fit for you. Going slightly long on the wheel diameter, won't make it hard to stuff, and can even help because with a bit of air it'll position itself deeper into the tire and stay away from the bead, lessening the chance of pinching.
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“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#8
Really Old Senior Member
https://sheldonbrown.com/harris/tires...tml#lesscommon
Your tire would be a 24X1.25. (1.125 would be 28MM, not 32MM)
24X fractional number such as 1-1/2, 13/8 etc. is WAY TOO big.
The decimal size BSD is 507MM
The fractional size BSD is 520 to 547MM
Your tire would be a 24X1.25. (1.125 would be 28MM, not 32MM)
24X fractional number such as 1-1/2, 13/8 etc. is WAY TOO big.
The decimal size BSD is 507MM
The fractional size BSD is 520 to 547MM
#9
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You might phone Kenda in Ohio. They keep a decent stock of odd size tires and tubes, and if they sold the size OEM for bikes destined for the USA, might have the exact tube available. They may sell you directly, or refer you to a source that stocks it. Another good source ofr odd (and normal size) tires and tubes is Yellow Jersey, in Madison], Wisc. They're good in that if they don't have it they're willing to try to find it, instead of just saying tough.
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“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#10
Twincities MN
Thread Starter
I'll be darned! The markings are wrong on the tire! I measured it. It's a hair under 32mm. So it's not 1.125 inches wide, it's 1.25.
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Last edited by kuan; 09-04-12 at 10:15 PM.
#11
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The SV9 is shown as fitting a range of tire sizes that includes the one you have (i.e. it's ok to use with a diameter in the range 507 - 541mm and a range of widths of 28 - 47mm, so it should fit a 507 - 32 tire) - so go ahead and use it.
As others have mentioned, tubes can stretch alot so it's not too critical to use the 'right' size. I've used a 700c (622mm) tube in tires as small as 12" (trailer tire) and it worked fine - just had to fold it up some. And when my daughter had a flat on her mountain bike at college (559mm tire) the only spare tube handy was also a 622mm. She rode on it every day for a semester without any issues before I finally changed it out with one of the correct size. With significant mismatches the main problem is making sure that none of the tube is pinched between the tire bead and the rim.
As others have mentioned, tubes can stretch alot so it's not too critical to use the 'right' size. I've used a 700c (622mm) tube in tires as small as 12" (trailer tire) and it worked fine - just had to fold it up some. And when my daughter had a flat on her mountain bike at college (559mm tire) the only spare tube handy was also a 622mm. She rode on it every day for a semester without any issues before I finally changed it out with one of the correct size. With significant mismatches the main problem is making sure that none of the tube is pinched between the tire bead and the rim.