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Yeah, dumb tube size question

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Yeah, dumb tube size question

Old 07-15-19, 03:22 PM
  #1  
nesdog
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Yeah, dumb tube size question

I've run Conti 25's for a long time and have always purchased 700 x 20-28 tubes.

On the new bike, I'm now sporting some Bontrager 28's...nice ride! Meantime, do I need to use a 700 x 28-32 tube with these or can I continue to mount the 20-28's like always?

Thanks...
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Old 07-15-19, 03:25 PM
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Either will work. Rubber isn't terribly precise.
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Old 07-15-19, 07:28 PM
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Originally Posted by nesdog View Post
I've run Conti 25's for a long time and have always purchased 700 x 20-28 tubes.

On the new bike, I'm now sporting some Bontrager 28's...nice ride! Meantime, do I need to use a 700 x 28-32 tube with these or can I continue to mount the 20-28's like always?

Thanks...
I use 18-25 conti tubes in a 28mm tire stretched out to 31-32mm. No issues - but I also run a fairly low pressure, 60 or below.
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Old 07-15-19, 07:56 PM
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What prompts this is that I grabbed some 28-32's for spares when I got the new wheels. I had assumed, incorrectly I guess, that I couldn't use my existing tubes on the 28 mm tires.

When I swapped out a damaged tube yesterday, the replacement was so large that it really wrinkled under the tire because there was extra material. Drove me nuts trying to smooth it out.

Interestingly, I just noticed that each vendor offers a slightly different layup; 18-23, 18-25, 20-28, 28-32. I didn't realize that these are not extremely specific, but cover a range of tire sizes.

So if I just stick with a 20-28, I shouldn't have the extra rubber in there and as mentioned earlier, will stretch to fit. Duh...
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Old 07-16-19, 01:06 PM
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nice reminder tho, that if we have an option, a little smaller might make tube changing, roadside, easier/faster
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Old 07-16-19, 01:35 PM
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I just used a 700x25-28c tube to repair my 650Bx48c tire to get home the other day, I've used 700x19-21c tubes on 32c tires. Tubes are pretty flexible(ha) in terms of acceptable range
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Old 07-16-19, 02:13 PM
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Originally Posted by nesdog View Post
What prompts this is that I grabbed some 28-32's for spares when I got the new wheels. I had assumed, incorrectly I guess, that I couldn't use my existing tubes on the 28 mm tires.

When I swapped out a damaged tube yesterday, the replacement was so large that it really wrinkled under the tire because there was extra material. Drove me nuts trying to smooth it out.

Interestingly, I just noticed that each vendor offers a slightly different layup; 18-23, 18-25, 20-28, 28-32. I didn't realize that these are not extremely specific, but cover a range of tire sizes.

So if I just stick with a 20-28, I shouldn't have the extra rubber in there and as mentioned earlier, will stretch to fit. Duh...
Yup. I learned this lesson myself and now err on the side of smaller.
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Old 07-16-19, 07:00 PM
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Originally Posted by nesdog View Post
I've run Conti 25's for a long time and have always purchased 700 x 20-28 tubes.

On the new bike, I'm now sporting some Bontrager 28's...nice ride! Meantime, do I need to use a 700 x 28-32 tube with these or can I continue to mount the 20-28's like always?

Thanks...
700x20-28 means it will fit 20 to 28. Yes your current tubes will fit.
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Old 07-16-19, 07:25 PM
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Originally Posted by rumrunn6 View Post
nice reminder tho, that if we have an option, a little smaller might make tube changing, roadside, easier/faster
Other benefits include them being lighter and you get to refine your puncture repair technique more often.
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Old 07-17-19, 07:03 AM
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Originally Posted by znomit View Post
Other benefits include ... you get to refine your puncture repair technique more often
cuz they are more stretched & more likely to puncture?
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Old 07-17-19, 07:49 AM
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Originally Posted by rumrunn6 View Post
cuz they are more stretched & more likely to puncture?
Exactly.
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