11

I've just replaced the tube on my bike and when I pumped it the valve wasn't particularly straight as can be seen in the image below.

Valve image

What I'm wondering is do I need to remove the tube and straighten it before use? I assume it wouldn't be any harm to do so but if there is nothing wrong with the way it is I'll save myself the effort. I'm going to be cycling it in the morning so I said I better ask before I do.

| improve this question | | | | |
  • 5
    If you don't straighten it the tube will fatigue and fail near the valve. Probably not in one day's use, but after several hundred miles, perhaps. – Daniel R Hicks Aug 19 '15 at 2:17
  • This spells trouble. The valve is in danger of being sheared off resulting in a sudden blow-out. This will almost certainly happen while braking hard. – Carel Aug 19 '15 at 9:24
  • 2
    @Carel - If it were in danger of "being sheared off" while braking hard the same danger would be there for a straight valve. The danger is from fatigue to the crimped/stretched rubber (though the result can still be a sudden loss of pressure as the tube rips open). – Daniel R Hicks Aug 19 '15 at 11:29
  • 2
    By the way, your tire is dangerously cracked and should be replaced. This may be from running at too low a pressure, or maybe just age. – Daniel R Hicks Aug 19 '15 at 11:32
  • Just another reason to not use tubes. – Deleted User Aug 19 '15 at 17:40
11

It should be straight out, perpendicular to the rim. Otherwise you risk damaging the tube.

When the valve stem is at an angle the valve isn't free in the hole – it is trapped by the edges of the hole where they bind the stem. The edges of the hole may cut the stem which will be moving a little bit as the tire and tube flex over bumps and the like.

There will also be an area of the tube that isn't supported by the rim (or that is stretched more than the rest of the tube) near the valve stem. That area is likely to be a weak point in the tube.

And one more thing! As pointed out in the comments below, there are conditions – such as the tire moving on the rim – that are likely to further stress the tube as it passes through the valve hole. If the valve is initially straight any angle of the valve is an immediate sign that something is happening.

| improve this answer | | | | |
  • 1
    While I agree, can you explain how and why it would damage the tube? – andy256 Aug 19 '15 at 1:55
  • @andy256: heavy braking with low PSI can result in tube movement within the rim. If the valve is already at the extreme end, then it could develop a cut where it joins the tube. – cherouvim Aug 19 '15 at 10:10
  • @cherouvim Yes, I was just suggesting that dlu add more detail :-) – andy256 Aug 19 '15 at 10:30
3

Straighten it. All you have to do is let the air out, push the valve in straight and then re-inflate it.

You may damage the tube near the base of the valve if you leave it as is when the tire takes a hit.

| improve this answer | | | | |
  • 6
    I find that that rarely works. In practice I have to deflate, physically pull the tube+tyre around the rim a little, then reinflate. – Móż Aug 19 '15 at 2:03
  • 3
    I agree with @Mσᶎ -- the tire should be deflated (let all the air out), then yank on the tire in a tangential direction to get things aligned. It's OK if it's not perfectly straight, but the above picture is too crooked by a factor of 2 or more. – Daniel R Hicks Aug 19 '15 at 2:19
  • 2
    I've been able to adjust by deflating and moving the whole tire and tube (pinch and slip it around the rim just a bit). – dlu Aug 19 '15 at 8:04
  • deflate, move/offset the tyre on the rim, making the valve straight, and inflate. – cherouvim Aug 19 '15 at 10:13
  • Another way to adjust is to deflate the tire, then "walk" the bike forward/back (as appropriate) until the valve is straight. – Daniel R Hicks Aug 19 '15 at 11:31
1

let ALL the air out, and pinch the tire on both sides all the way around to free it from the wheel rim as it may be sticking on there - then it should usually slide when you yank it

| improve this answer | | | | |
  • Welcome to the site! Although there's nothing wrong with answering old questions, your answer doesn't really add much to what's already here. (Technically, it doesn't answer the question, either, since the question is "Do I need to fix it?" not "How do I fix it?" but I don't think that's a big deal, in this case.) Please do have a look at our brief tour for more information on the site. – David Richerby Aug 27 '17 at 10:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.