Measuring spokes without removing them from a wheel
 

Is it possible to measure the length of some spokes to ball park accuracy while they are on a wheel without having to remove one ? Can I just measure from the j hook edge to where the nipple meets the rim ?

Thanks

J

You can try it if you're in a bike shop with a bored but friendly mechanic letting you measure various length spokes. When you go to replace a spoke, it's a good idea to match them for length.

What are you trying to do here? If you're just trying to get a spare spoke, you'll do better to use one of the spoke length calculators available on-line with the rim and hub information.

The threads are usually 10mm long. If the spokes cross, that'll make the measurement harder. I agree with pdlamb.

Measure from the edge of the hole to the start if the nipple. Add 12 mm if the nipple looks short, like in most cases. Old bikes might have 14 mm.

Spoke elbow to rims ID then add up to 3mm. About 2 for the nipple head and 1 for the crossing's added distance. Andy

I have about a dozen bikes that I have been tasked with finding spoke lenghts for front and rear . I'm trying to avoid removing 24 tyres and 24 spokes if at all possible.

things that will be consistent in a mass produced spoke is how much is threaded

Tire and rim strip off, you should be able to see the end of the spoke.

the 0 for measuring is the inside of the hook spoke rulers hang that end from a hole in them..



~o)

Do what Andrew said to do. That will yield an accurate number.

This will come op short because you forgot to allow for the rim's wall thickness. Unfortunately, this can certainly a sizeable variable, ranging from 2 to 6mm depending on the rim itself and whether it has eyelets.

If you measure to the end of the nipple and add the nipple length, as mentioned earlier, you'll be spot on. Of course nipple come in a few lengths, but you can usually know which BTW sight.

On most rims, I use my X-ray vision to locate the top of the nipple, and measure to there against the side of the rim.

That's something that is commonly done in shops. No, you may not get exactly the right length, but by measuring to the rim edge and adding about 4mm you will be safe enough.

My bike shop did that, I don't know if they added the 3mm, but they came up about 2mm short... bought a whole box of the wrong size.

This is the completed tensioned wheel with a bare spoke for reference.
https://lh3.googleusercontent.com/wn...=w1024-h768-no

Liks like the correct length to me?

No, look again. Assuming the rim has a minimum wall at the hole, the end is barely reaching the far side, and has no hope of engaging the head.

Take a look at this image, and you'll see that he needs 3-4mm more.

http://4.bp.blogspot.com/_FkxX587Lsi...ple+thread.jpg

As I said earlier, measure to the inside of the rim + rim wall + 3-4mm to engage the head (including an allowance for length lost to the over/under weaving).

FWIW - I like spokes to reach very close to the top of the nipple, but if you do the same make sure there's room for overrun, lest you run out of thread if off 1mm or so.

I may not being seeing the photo correctly, but it looks to me as though the spoke is touching the rim I.D. and just ~2mm short of bottoming out at the spoke head??

No, you should never see threads on a correctly built wheel.

If I had to figure out 24 wheels, I think I'd use the spoke calculator and plug in the rims and hubs and the crossings of each wheel as built. I think that is going to get you a better number than the various measurements that are not going to account for rim thickness.

No, you're seeing it exactly right. The spoke reaches the rim, but doesn't go beyond to engage the spoke head on the opposite side.

BTW - I fixed the picture in my prior post.

here it is again.

http://4.bp.blogspot.com/_FkxX587Lsi...ple+thread.jpg

Yes, I should have included a few MMs for the rim thickness. Andy

Compost happens. You can get me next time.

I'd measure from the hub (elbow) to the nipple. Add nipple length (usually 12, or 14 mm). Then deduct the length between the top of the nipple, to the end of the spoke on the inside of the nipple. If a spoke protrudes through the nipple to the other side, or is 3, or more mm beneath the tyre end of the nipple, the original spokes were too long (or too short in case it ends too "deep").