Sunday, 9 May 2010

36-spoke bicycle wheel build

KorganIconThis is a how-to on building a 36-spoke wheel. I had a hard time finding simple explanations online and, now that I understand it, I can explain it.

This tutorial assumes you already have the correctly-sized parts and are ready to start building.

Equipment: Rim, Spokes, Nipples, Hub.
Tools: flat-headed screwdriver, Spoke wrench.

The process of threading the spokes can be broken down into simple parts:

  • There are 36 spokes. The wheel has 2 sides. And so, each side will have 18 spokes.
  • On each side of the wheel, half the spokes go clockwise and half go anti-clockwise. And so, there are 9 spokes in each direction. We deal with only 9 spokes at a time.
  • There are 36 holes in the rim and there are 18 holes in each side of the hub. And so, when we thread a group of 9 spokes, we use half the holes on one side of the hub and a quarter of the holes on the rim.

Here are the directions (images below):

  1. Put 9 spokes into every 2nd hole on one side of the hub. The spokes enter the holes downwards, so that they point to the opposite side of the hub (pic. 1).
  2. Connect these spokes to every 4th hole in the rim (pic. 3). When screwing the nipples on, only do it for 4-5 turns. They need to be kept loose. If you tighten them, it will make things very difficult later.
  3. Flip the wheel over (pic. 4).
  4. Put a spoke in every 2nd hole again, downward. But note this first:
    The holes on either side of the hub are not aligned. This means that when you put a spoke in one hole on one side of the hub, it will hit between two holes on the other side. It's like there is a hole on the second side that is slightly ahead of each hole on the first side.
    So, choose a spoke to connect. This spoke will be in a hole in the hub that is slightly ahead of a hole on the opposite side of the hub. Find that spoke on the opposite side. Find the hole in the rim it is connected to. Choose the empty hole ahead of that spoke, and connect your chosen spoke to it. Easy! (pic. 5 is how to do it. Pic. 6 is how not to do it.)
  5. The remaining 8 spokes will continue as normal, connected every 2nd spoke to every 4th hole in the rim. (pic. 7)
    That's the trickiest part of threading the wheel over with.
  6. On the side of the hub you’re working with, put 9 spokes upwards into the remaining 9 holes.
  7. Twist the hub anti-clockwise, so that all the spokes now connect to the rim at an angle pointing clockwise.(pic. 8)
  8. The next 9 spokes will connect to the rim in the opposite direction to the twist.
    Choose one of these spokes. Heading anti-clockwise, this spoke will go over the 1st spoke to its left, over the 2nd spoke to its left and under the 3rd spoke to its left. See the diagram. You skip the first hole in the rim you come to and connect to the next hole. This is the 2nd tricky part to threading a wheel. So make sure you understand it correctly. Just remember: over, over, under, skip a hole, connect. (pic. 9)
  9. Repeat for the remaining 8 spokes. (pic. 10 & 11)
  10. Flip the wheel over and do exactly the same thing. (except you don't have to skip a hole this time, there's only one left for each spoke to go into, and you thread clockwise.) (pic. 12)
  11. You have now connected all 36 spokes. Well done!
    All that’s left to do is tighten all the nipples and true your wheel.

Notes on truing:
Truing your wheel means making your wheel as straight as possible. You will need a truing stand for this or, for crude truing, you can use your brake pads as a guide.

Simply, you spin your wheel and watch as the rim jostles from side to side as if it were buckled. Watching the rim move between the brake pads as it turns, or the pins on a truing stand, makes this easy. You find the part of the rim with the worst buckling and you tighten or loosen the spokes at that point accordingly: if the rim leans to the left, you tighten the spokes on the right, and vice versa. If the tire is on, you use a spoke tool to do the tightening or loosening. If the tire is off, you might get away with using a screwdriver only.

Only tighten the spokes with a half turn or a quarter turn at a time. If the spokes are already tight on one side, you would instead loosen the spokes on the opposite side. You then repeat with the next worst buckle in the wheel until the wheel is straight enough for you.

Other notes:

You'll notice that the rim holes aren't exactly in the centre of the rim. One will be closer to one side, the next will be closer to the other side and so on. Obviously, you will thread the spokes on one side of the rim to the holes nearest the same side.

Lastly, if you're threading your wheel and it seems your spokes are too long, then try this: with longer spokes, the solution may be a small change in step #8. Instead of skipping three spokes before threading, try skipping four. In other words, try over, over, over, under, skip a hole, connect. I did this the other day with an older wheel and it worked perfectly.

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