2

Got an old bike that I restored some time ago, and the original tubes literately burst on me today (I knew I should have replaced them long ago, they are probably 10 years old) and now I have some questions on replacing them.

Looking at the available tubes, I see most of them have presta valves. The originals and my current replacements are Schrader. I don't have much preference on valve, I just want to know if I should limit my selection.

The real question is, I really never paid any attention to the holes drilled in the rims. Do they have different diameters for each type? Would a larger Schrader hole damage a presta valve tube? Or are the rims pretty much universal?

If this is useful, the rims i'm buying new tubes for are: an old MTB Araya RM-20 and an unmarked original from a cheap fuji-4.0 700 bike

Improve this question
2
  • 1
    You can install a presta valve tube in a schrader valve drilled rim (though sheldon brown advises using a grommet like Moz's answer below). If you have a presta valve drilled rim, a schrader valve won't fit. However, provided the rim is sufficiently strong and wide (i.e. do this at your own risk), you can enlarge the valve hole with a 21/64 inch drill bit and fit schrader valves. FWIW, its pretty easy and same price to get schrader valve tubes (just go on amazon or your local sporting goods store and look around).
    – Batman
    Jan 5, 2014 at 6:18
  • You should make an effort to get Schrader tubes if you have rims drilled for them. A Presta stem installed in a Schrader rims, without a grommet adapter, will tend to force its way through the hole and is apt to fail around the stem. Tubes of the proper type should be available from a well-equipped shop. (What size are they -- what are the numbers on the side of the tires?)
    – Daniel R Hicks
    Jan 5, 2014 at 13:32

1 Answer 1

Reset to default
5

Yes, the holes are different sizes. 6mm and 8mm, from memory. The hole size matters if you have skinny rims as 8mm out of a 20mm rim is a lot compared to 8mm out of a 40mm rim. But you already have valve holes.

In theory putting a presta valve in a Schrader-size hole matters, in practice it doesn't.

The base of the valve is where you'll see any effect from having a presta valve in an oversize hole, and in theory the base of the valve will get cut up by the edge of the rim. You might also get dust or water inside the rim if you have a V or box rim.

In practice it doesn't seem to matter. I do this fairly often because almost all my rims are drilled for schrader but I'll fit presta tubes rather than ride on flat tyres). I've seen marking around the base of the valve when I've pulled the tube out, and occasionally it's bulged up 2-3mm.

If you look at the locking ring/nut that comes with Schwalbe presta valves it's got a smooth face under the knurled section that's exactly the right size for a schrader hole, suggesting that they expect people to use them that way.

presta valve enter image description here

The ring I'm talking about has an arrow in this pic, and @jimrings found the pic on the right.

There are a couple of other types of adapters. You can see the most common ones in the pic below.

Presta-Schrader rim hole adapters

The ones to the right and left push through the rim from the inside and hold the valve centered in the rim. The rubber one on the right actually attaches to the rim. The metal one on the left is fitted over the valve before inserting it into the rim.

Improve this answer
4
  • 2
    Is this Panaracer one similar to the Schwalbe ones you mention?
    – jimchristie ♦
    Jan 5, 2014 at 5:34
  • @jimirings yes, exactly. Image copied, thanks!
    – Móż
    Jan 5, 2014 at 5:35
  • If you are running presta valves in a schraeder rim you should be using something like [stem savers][1] to prevent the valve stem from being sawn off. [1]: wheelsmfg.com/presta-stem-savers.html
    – DWGKNZ
    Jan 5, 2014 at 10:15
  • Awesome info. thanks everyone! I just took the tube out of the tire (1st flat since i got that vintage bike), and it turned out to have a rip exactly where the valve meets the rim... so i will pay close attention to this! I like the rubber gasket idea better (right on last pic), but i will probably use the metal (center on last pic) for a while since it came with the cheap kendra tube i had lying around.
    – gcb
    Jan 5, 2014 at 20:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

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