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The rubber protection cover does not pass through the hole in the rim. Something can be done or not a fit?

This valve has a rubber reinforcement that does not pass through the hole in my rim. The hole is only as wide as to pass the top part of the valve.

Is this tube just not a fit for my rim or there is some way to fix the situation?

  • Would it be reasonable to drill a wider hole (it is a rather wide MTB rim)?
  • Can I remove or soften the rubber reinforcement?
  • Or something else?

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    Would it be reasonable to drill a wider hole No! If you don't do that properly, you'll leave imperfections in the rim material, which is almost certainly aluminum. Those imperfections will be stress risers and quite likely to lead to your rim cracking. Unlike steel, aluminum is already inherently prone to cracking and has no fatigue limit, making it difficult to safely machine or drill aluminum because stress risers in aluminum lead to rapid failure. Dec 10, 2022 at 15:04
  • This can be the answer, ok
    – nightrider
    Dec 10, 2022 at 17:07
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    Would it be reasonable to drill a wider hole? Yes, drilling a valve hole to make it larger is fine. Even enlarging a 6.5 mm Presta hole to a 8.5 mm Schrader hole is generally no problem. It's done all the time in bicycle shops. Just use a sharp drill, don't be sloppy or forceful, and your rim will be fine. Dec 11, 2022 at 14:32
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    @AndrewHenle: the difference in hole diameter is about 1mm. If bike parts were that sensitive, they'd explode at the first hard bump. It's not a seriously loaded area. It'll be fine. Dec 11, 2022 at 18:56

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First a general answer: Yes, drilling a valve hole to make it larger is fine. It's done all the time in bicycle shops.1

I've seen lots of rims crack at the nipple holes, but I've rarely (if ever) seen a rim crack at the valve hole. It's not a problem.2

Of course, in order to do a good job, one should use a sharp drill, not apply too much force, clean the hole with a file afterwards, and make sure there are no shards or shavings that could damage the tube.

Presta valves need 6.5 mm holes, Schrader and Dunlop valves need 8.5 mm.3

Now to your case: Since the top part of the valve passes through the valve hole, the valve hole is obviously made for Schrader valves.4

But maybe the valve is a bit thicker because of the rubber, or maybe the valve hole is a bit too small. Either way, you only need to make the hole a little bit larger. (I'd measure the hole and the valve with a caliper to get a better idea of what's going on.)

I guess you need to make the hole at most 0.5 mm larger, probably less. You might even be able to do it with a file without too much effort. But if you want to use a drill – sure. Just make sure you get one with the correct diameter, i.e. at most 0.5 mm larger than the current hole.

(I guess you could also remove the rubber from the valve, but to make sure the valve really goes through the hole you'd probably have to remove the rubber all the way down to the tube, and then I'd worry that the whole thing isn't airtight anymore or even comes apart. And you'd have to repeat the operation with each new tube that has a similar problem. Making the hole larger seems like a cleaner solution.)

1 Maybe more so here in Europe where Dunlop valves are quite common, which have the same outer diameter as Schrader valves. A rim with a Presta valve hole needs be drilled to accomodate the larger diameter.

2 Well, with an extremely light rim, e.g. a narrow 622 rim below 450 g or so, I'd maybe think twice. But generally it's fine.

3 See e.g. Ryde's specifications here and here.

4 It's almost certainly not a Presta valve hole, as some commentators seem to think.

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    You're going to want needle files to hand to make sure the edge is smooth where it touches the rubber. I'd start by going up 0.5mm with a drill, then finish by filing. Overall I think it's an unlucky combination of a slightly tight hole and a slightly thick rubber coating. I've got a few of these, fitted one yesterday in fact, and they're usually OK with a bit of a push
    – Chris H
    Dec 12, 2022 at 6:39
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I agree with @Andrew Henle that it is of questionable wisdom to bore a wider hole to fit a Schrader valve stem into a rim designed to use the much thinner Presta valve stem. The fact you can start your Schrader valve into your rim infers that it is not a rim drilled for a Presta valve, which is a mm or more smaller and would not accommodate even starting the Schrader valve. A work around may be to use a Presta valve tube. While not as ubiquitous as Schrader valve tubes, they are not hard to find even in well-stocked hardware or department stores that have minimal bike accessories.

All that being said, boring the valve hole larger to accommodate a larger valve stem has been done successfully and without issue. Even when internal widths of MTB rims were 19mm. To mitigate possible damage from improper drilling, you might try to use a medium to fine coarseness round file like is used to sharpen the cutters of a chainsaw chain. These are very hard and using them on aluminum would be quick but require a conservative approach to not bore out the hole larger than necessary. A fine line drawn around the perimeter of the current valve hole will help guide the width and roundness of the bore. The soft aluminum can quickly fill in the gaps of the file's teeth making it less effective. A wire brush can clean these but in this instance, there is likely to be so little filing necessary that this won't be a problem. Be sure to smooth any burrs within the hole with some fine sandpaper to prevent damage to the rubber stem. This, too, is not likely to be a problem using a round file to bore the hole.

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    It is absolutely not Presta.
    – nightrider
    Dec 11, 2022 at 6:36
  • There is almost 0 percent chance the rim was designed specifically for presta, as in there is almost no chance the sm as ll difference in size is critical to the integrity of the rim. It's drilled for presta because most of the customers use presta. If bike parts were that sensitive, they'd explode when you hit the first pothole. Dec 11, 2022 at 18:54
  • Point taken. Answer edited to better reflect fact that since OP could start the Schrader valve into the stem hole, it's not going to be a Presta drilled rim.
    – Jeff
    Dec 11, 2022 at 20:00
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I've had this in the past. I ended up chamfering the square lip of the rubber reinforcement, then forcing it through the Schrader hole in the rim. I was roadside and I vaguely remember using spit as an emergency lubricant, water bottle was empty. Lots of rotational wiggling and pulling with a leatherman helped - I put the cap back on to protect the threads from the tool's jaws.

You could also cut the reinforcing rubber down to a few millimetres above the the tube - the brassy stem will go all the way through (or it should!!)

If you have a lot of these tubes, it may help to chamfer the inner edge of the hole in the rim, but that can be difficult to do nicely. A deburring tool might work nicely.

I would not drill the hole larger, though I might use a tapered bore reamer to slightly enlarge the hole. Be aware this may make future normal tubes a bit of a loose fit.

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If and when you do drill the hole, drill from the inside of the rim to the outside, then clean off the burr. This way makes it easier to file the burr down and also if you don't do a clean job any remaining material will be on the outside and not rubbing against the tube itself.

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  • What do you mean by "inside" and "outside"? I guess "inside" is the side that will be covered by the tube and tyre, but I'm not sure... Feb 19, 2023 at 4:11

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