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I recently replaced my rear wheel (hooray for figuring out how to remove the cassette). Now I am about to put the old tube in the new wheel. I noticed the new wheel doesn't have any rubber lining to protect the tube from the metal as my old, now broken, wheel did.

Is this an important barrier?

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  • This could be a good chance for experience-based learning. Try fitting your (oldest most patched) tube to a rim without rim tape and inflate it to a decent pressure. Leave it inflated over night and see what happens. Note - I wouldn't actually ride it in this state though.
    – Criggie ♦
    Commented Jan 30, 2019 at 23:08
  • @Criggie neat idea. Also, update: I replaced the wheel and rode it for 1.5 days before the derailleur was stabbed by a sidewalked christmas tree and bent up into the spokes.
    – colorlace
    Commented Jan 30, 2019 at 23:29

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Yes, you will need a rim tape to protect your inner tube from the spoke holes or the spokes in your rim. There are a few exceptions we come to later.

The rim is the outer part of your wheel. Along its or circumference run two flanges to hold the tyre in place. Between the flanges is the rim bed. A rim tape usually needs to be in this bed. Thus can be a glued cloth tape, a strong adhesive tape, a strong elastic tape, or a rubber strip.

Often the rim profile consists of a chamber. It's one end is the rim bed and the other the inner circumference of the rim. The latter has drilled holes for spokes and nipples. The former has wider holes to access the spokes.

Purpose of the rim tape is to prevent the inner tube from expanding into these holes. The rim tape has to be quite strong to prevent this under pressure.

The tape should also cover the whole width of the rim bed. This keeps it from sliding.

If the inner tube expands into the holes it may burst. Either for being over-strained or by rubbing at a burr from drilling.

Some rims have only one chamber. This was especially common in the days of steel rims. Here the inner tube may be protected by a soft strip of rubber from chafing at nipples.

If a rim has no spoke holes you do not require rim tape to cover the holes. However, it provides an insulating layer to protect the inner tube from heat coming from the brake track. There are plugs available to cover holes, where the same may apply.

Another exception are tubular tyres that are glued to the rim. But these are only found in sophisticated race bikes.

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    "liner" means an optional extra layer between tube and tyre, as compared with rimtape which is on the other side of the tube.
    – Criggie ♦
    Commented Jan 29, 2019 at 3:45
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    Some sources argue that rimtape should also be used with unholed rims, especially with rim-brakes since it insulates the hot rim from the inner tube which might cause them to explode.
    – Carel
    Commented Jan 29, 2019 at 11:23
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    Cheers Criggie & Carel i edited accordingly.
    – gschenk
    Commented Jan 29, 2019 at 11:30
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    As someone that has never had a road bike or expensive bike, the "one chamber" rims are the only thing that I've ever seen. I'm not sure if I would call those "special or very old". They are just cheap and common. I'd expect every bike sold at a department store to have those type of rims.
    – JPhi1618
    Commented Jan 29, 2019 at 20:05
  • @JPhi1618 I've not seen those except for steel rims or very wide carbon rims. Not even in so called BSOs. What is more, I thought it were not even possible for aluminium rims. I shall edit my answer to make it more neutral.
    – gschenk
    Commented Jan 30, 2019 at 13:08
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That's called rim tape and it protects the tube from sharp edges in the rim and the ends of the spokes and spoke nipples. Without it you will get endless punctures.

Most wheels come with rim tape installed, but you can buy it separately. It's not hard to install, you just have to make sure you get the right width for your rims: wide enough to cover the inside of the rim but not too wide so it interferes with the tire bead.

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    Note that there are several different varieties of rim tape. One form is a flexible rubber ring, made out of essentially the same material as an inner tube. Another is a sort of "adhesive tape" that is wrapped around the rim and lapped a few inches near the valve. One can also obtain perfectly acceptable service from fabric electrical tape or "duct tape" torn into an appropriate width and wrapped around the wheel. I personally prefer to use "hockey tape". And there are several special choices more intended to be used with tubeless tires but perfectly functional with tubes.
    – Daniel R Hicks
    Commented Jan 28, 2019 at 23:42
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    Daniel, the duck tape one surely works only for very small pressures? I've stained tensilized strapping tape close to the point of failure at just five bar. And that's the stuff Stan's Tubeless tape is made from (just heavier weight than mine). Duck tape would have hard much worse I presume.
    – gschenk
    Commented Jan 28, 2019 at 23:48
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    @gschenk - The typical rim hole is (very roughly) around one cm in diameter. At 5 bar (72 psi) that's 11 pounds of force, and the tube is absorbing most of that. The tape is present mainly to keep the tube from swelling into the hole to where it contacts the spoke end. If you've ever seen one of the thin rubber rim strips shipped on most pre-assembled bikes you'd understand that they are exceedingly flimsy in comparison to most other options, and they can last for decades.
    – Daniel R Hicks
    Commented Jan 29, 2019 at 1:51
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    @DanielRHicks and the tube is absorbing most of that Not really. The tube absorbs almost none of the force. If the tube absorbed force from the air inside it, then it wouldn't be able to keep the tire firm. Thin rim strips work because the tube isn't only pressing against the hole, it's pressing the rim strip against the rim and holding it tightly in place. Take a look at something like a Continental high-pressure rim strip that's been in place a few years. There are dents pressed into the strip where the spoke holes are - from the tube pushing against the strip.
    – Andrew Henle
    Commented Jan 29, 2019 at 13:22
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    @timwiz No need to get confused. Just think about what happens to a tube when you try to inflate it to bike riding pressure levels without a tire around it. The tube will get huge without building up any real pressure, and will burst a long time before you can inflate it to any meaningful pressure. It's really the job of the tire to withstand the pressure, the tube only acts as a seal.
    – cmaster - reinstate monica
    Commented Jan 29, 2019 at 19:50
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The rubber lining is called Rim Tape. Its designed to stop the tube being punctured by the ends of the spoke nipples that poke through the wheel rim . If the wheel is double walled then the spoke nipples are recessed and the rim tape can stop the tube expanding into the access holes to the nipple. It also hopefully stops the tube wearing on the edge of the hole that allows the inner tube valve through the wheel rim.

You could take the rim tape off the old wheel and use that or a new one would only be about £1-3. I would recommend using one.

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