7

The last couple of wheels I've built have been all from reused parts. One was to convert my unicycle from 24" to 20" largely as an experiment, and the one that I'm currently working on is for the junk bike I keep near work.

For the unicycle wheel, I found my spokes were about 1mm too long nominal, plus measuring error, and ordered a bag of (round) nipple washers. They were 0.5mm thick, and I'm not sure if the were strictly needed in the end.

For the 26" wheel, the spokes are more like 2mm too long, so I reckon I'll run out of thread before the wheel is fully tensioned. I'd like it built quickly. Ordinary M4 washers are dirt cheap and available same-day. New spokes are probably more than the bike is worth (even cheap ones) but what really puts me off is the several days delivery time. So I'm considering using 1 (or even 2 on the drive side) M4 washers (0.8mm thick) under each nipple. They seem to be a good size for both nipples and rim. The extra thickness is good but obviously adds weight - not an issue on a bike made of gas pipe.

Am I missing something? Are round nipple washers just thinner and harder to obtain than normal washers (I know there are other shapes for narrow rims). Is it just about weight?

5
  • Guessing - it might be about tolerances for the inside bore of the washer vs the outside diamerer of the spoke nipple?
    – Criggie
    Nov 28, 2022 at 10:13
  • 1
    Related (not a dupe) bicycles.stackexchange.com/questions/45638/…
    – Criggie
    Nov 28, 2022 at 10:15
  • 1
    @Criggie possibly, but the nipple washers seem like a looser fit.
    – Chris H
    Nov 28, 2022 at 10:31
  • 1
    Just a drive-by: If your wires are thick enough (usually they are), it might be worth buying the right die, which would allow you to extend the threads and then you could hecksaw/file the spoke shorter, to fit.
    – yo'
    Nov 28, 2022 at 21:57
  • 2
    Congrats for hitting the HNQ !
    – Criggie
    Nov 29, 2022 at 4:30

4 Answers 4

7

This is a really short answer:

I use brass washers in this type of scenario which deform to the rim shape and the nipple. This was the recommended type of washer in one of the books I read when learning the subject, possibly Brandt's book or another similar.

The wheels where I have had to do this have built up nicely. Using washers is good anyway as the nipple turns more easily under high tension than it would against the plain rim surface.

5

The washers need to fit the rim. If the part of your rim where the spoke holes are, i.e. where the washers will sit, is not flat, your washers will sit on two points rather than on a flat face. As a result, the forces from the spokes are entering the rim via these points. This will either deform your rim, or your washers, but my guess is you will deform the rim.
That does not sound like a good idea to me. I would expect early failure of the rim. You might want to bend the washers, ideally to the same shape as the rim inside, or bent somewhat more, which would mean the force is distributed over a line rather than over two points. Keep in mind that the topmost spoke at any given position carries most of the combined weight of bike and driver for that wheel (~70% on the back, ~30% on the front wheel) plus any impulse from bumpy roads, so the forces are by no means negligible, and if the rim breaks, it will be while you are driving, so you risk injury.
Also, depending on your rim, your nipples might protrude too far inwards, making damages to the inner tube quite likely.

You may want to shop for a cheap wheel, which might actually be cheaper than a set of new spokes, or search for cheap spokes on ebay.

6
  • In my experience washers are so soft that they easily deform to fit the rim. At least the DT Swiss PHR washers. If the rim has eyelets it will already have a flat and strong surface for the washers to sit on.
    – Michael
    Nov 28, 2022 at 10:28
  • @Michael that's another advantage of proper spoke washers then
    – Chris H
    Nov 28, 2022 at 10:37
  • In both of these cases they were flat, wide single-wall rims, so the washers will spread the load rather than concentrating it. The the rim tape also has to work pretty hard in protecting the tube from the nipples, which is partly why I don't want the spokes sticking out at all.
    – Chris H
    Nov 28, 2022 at 10:41
  • I've had a rim fail from a spoke pulling through (alloy, as all of my rims are). I'd been riding for several days like that before finding time to true the wheel and realising why it had gone out of true. That was with 32 spokes, these have 36. I reckon the injury risk is negligible (20-spoke carbon wheels would be a different matter) and I deliberately asked in a general way.
    – Chris H
    Nov 28, 2022 at 10:42
  • 3
    I think Jobst Brandt effectively blew away the argument that the weight of the bike hangs from the topmost spoke. This could be easily demonstrated with a tensiometer. Only the very bottom spokes can lose any tension, the rest of the load is shared all around the rim
    – Noise
    Nov 28, 2022 at 20:29
2

The best way is not to use washers at all, save your money for a threading tool, it's about the same price. Perhaps from an online hobby shop where they make very small bolts. It may be difficult to find a 1.7mm one, perhaps post a thread to ask where to source them.

If you spin the threading tool onto the ready-made spoke thread, it will glide on easily, and when it gets to the end you can turn another 5 times for an extra mm of thread, maybe just jam the elbow of the spoke very loosely in a vice. and then cut of 1mm at the top with a sharp pliers before unscrewing the threading tool through the new cut.

Chances are you wouldn't even need to rethread them if it's just 1mm, they may have 2mm extra thread to start with.

10
  • 5
    Am I right in assuming that by "threading tool" you mean a die? Because spoke threads aren't cut with a die, they're rolled, and a cheap rolling machine costs about enough to buy two hundred custom size spokes.
    – Chris H
    Nov 28, 2022 at 18:50
  • 3
    @ChrisH The cold work done by rolling adds significant strength. I would be a little hesitant to substitute with cut threads.
    – MaplePanda
    Nov 28, 2022 at 19:17
  • 2
    @MaplePanda yes, I wouldn't even consider cut threads here, even if I could get a die the right size. I don't want to be too critical of the answer until I know for certain what's meant (but the lack of a mention of the thread pitch also doesn't inspire confidence).
    – Chris H
    Nov 28, 2022 at 19:31
  • 1
    @Noise that's why I was thinking clarification was needed, rather than dismissing the suggestion out of hand
    – Chris H
    Nov 28, 2022 at 20:26
  • 2
    @LifeInTheTrees yep - grab any spoke, and use calipers to measure the thread OD and the shaft OD. The threads will be wider than the shaft because of displaced metal. A die cannot do that, because threads are cut by a die, leaving the OD to be no more than the original shaft's OD.
    – Criggie
    Nov 29, 2022 at 4:32
1

#1: Do not use a die on spokes. They are rolled...Spoke rollers are not cheap, but it's the only way to make spokes that last.

#2: Washers, especially varying amounts of washers between spokes is not a good idea. You'll have wheel wobble when you go past ~30 km/h.

#3: Using washers is legit in some cases. In fact, sometimes better - provided that you have washers made from softer material then the rim, and equal amounts of them across each spoke.

#4: Wheelbuilding is the most serious thing about bikes - do not do it in a rush, you'll regret it later. Take time to buy properly sized spokes. You don't need to go fancy like Sapim or DT Swiss. I used fancy spokes. I used dirt cheap, simple spokes. Not a huge difference if you have correct length, proper tension and great wheel truing.

Happy riding!

1
  • Are you thinking about wobble caused by the weight variation? One odd washer would make less difference than the valve or a reflector, and what I've got in front of me here has better symmetry than that - double washers on every drive side spoke to get the dish.
    – Chris H
    Dec 7, 2022 at 6:57

Your Answer

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

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