raggiare una ruota

Ecco un’altro bell’articolo  che insegna passo passo come raggiare una ruota. L’articolo é in lingua inglese che volutamente non ho tradotto . L’articolo é tratto da: www.sheldonbrown.com

The “key” spoke

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The first spoke to be installed is the “key spoke” .

This spoke must be in the right place or the valve hole will be in the wrong place, and the drilling of the rim may not match the angles of the spokes. The key spoke will be a trailing spoke, freewheel side. It is easiest to start with the trailing spokes, because they are the ones that run along the inside flanges of the hub. If you start with the leading spokes, it will be more awkward to install the trailing spokes because the leading spokes will be in the way.

Since the key spoke is a trailing spoke, it should run along the inside of the flange. The head of the spoke will be on the outside of the flange. (see the section “Which side of the flange?”)

It is customary to orient the rim so that the label is readable from the bicycle’s right side. If the hub has a label running along the barrel, it should be located so that it can be read through the valve hole. These things will not affect the performance of the wheel, but good wheelbuilders pay attention to these things as a matter of pride and esthetics.

Rims are drilled either “right handed” or “left handed”. This has to do with the relationship between the valve hole and the spoke holes. The spoke holes do not run down the middle of the rim, but are offset alternately from side to side. The holes on the left side of the rim are for spokes that run to the left flange of the hub. With some rims, the spoke hole just forward of the valve hole is offset to the left, with others it is offset to the right (as illustrated). Which type is “right handed” and which “left handed”? I have never met anyone who was willing to even make a guess!

The key spoke will be next to the valve hole in the rim, or one hole away.

As viewed from the right (sprocket) side of the hub, the key spoke will run counterclockwise, and it will go to either the hole just to the right of the valve hole (as illustrated) or the second hole to the right, depending on how the rim is drilled. The aim is to make the four spokes closest to the valve hole all angle away from the valve, giving easier access to the valve for inflation.

Screw a nipple a couple of turns onto the key spoke to hold it in place. Next, put another spoke through the hub two holes away from the key spoke, so that there is one empty hole between them on the hub flange. This spoke goes through the rim 4 holes away from the key spoke, with 3 empty holes in between, not counting the valve hole.

Continue around the wheel until all 9 of the first group of spokes are in place. Double check that the spacing is even both on the hub (every other hole should be empty) and the rim (you should have a spoke, 3 empty holes, a spoke, etc. all the way around. Make sure that the spokes are going through the holes on the same side of the rim as the flange of the hub. It should look like this:

 

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The second group

Now turn the wheel over and examine the hub. The holes on the left flange do not line up with the holes on the right flange, but halfway between them. If you have trouble seeing this, slide a spoke in from the left flange parallel to the axle, and you will see how it winds up bumping against the right flange between two spoke holes. Turn the wheel so that the valve hole is at the top of the wheel. Since you are now looking at the wheel from the non-freewheel side, the key spoke will be to the left of the valve hole.

If the key spoke is next to the valve hole, insert a spoke into the left flange so that it lines up just to the left of where the key spoke comes out of the hub, and run it to the hole in the rim that is just to the left of the key spoke.

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The illustration shows it viewed from the right side:

In the illustration, the key spoke is right next to the valve hole. Some rims are drilled with the opposite “handedness”, so this may not be the case for your wheel.

If the key spoke is separated from the valve hole by an empty spoke hole, insert a spoke into the left flange so that it lines up to the right of where the key spoke comes out of the hub, (looking at the wheel from the left!) and run this tenth spoke to the hole between the key spoke and the valve hole

If you have done this correctly, the spoke you have just installed will not cross the key spoke. When you flip the wheel back around so you’re looking from the right side, if the tenth spoke is to the left of the key spoke at the hub, it will also be to the left of it at the rim. Like the first group of spokes, it will be a trailing spoke, it will run along the inside of the flange, and the head will face out from the outside of the flange. Install the other 8 spokes in this group following the same pattern.

At the end of this stage, the wheel will have all 18 of the trailing spokes in place. In the rim, there will be two spokes, two empty holes, two spokes, two empty holes…etc. as shown below:

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The leading spokes

 

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Turn the wheel back around so that the freewheel side is toward you. Insert a spoke into any hole, but this time from the inside of the flange. Twist the hub clockwise as far as it will conveniently go. Since we are building a cross 3 wheel, this new spoke will cross 3 trailing spokes that go to the same flange of the hub.

The first two crosses, this spoke will pass outside of the trailing spokes, but for the outermost cross it should be “laced” so that it goes on the inside of the last trailing spoke. You will have to bend this leading spoke to get it around the last trailing spoke on the correct side.

After this leading spoke has crossed 3 trailing spokes, there will be two possible rim holes to connect it to. Use the rim hole that is on the same side as the flange you are working from. It should not be right next to one of the trailing spokes that runs from the same flange of the hub.

Install the other 17 leading spokes following the same pattern. If you can’t get some of the spokes to reach their nipples, make sure that the nipples on the trailing spokes are seated into their holes. When you are done, double check around the rim to make sure that every other spoke goes to the opposite flange of the hub.

Different cross numbers: The instructions above are based on a normal cross 3 pattern. If you are using a different cross pattern, substitute the appropriate numbers in the instructions above. With any cross number, only the outermost crossing is “laced” so the spokes go behind one another.

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Which Side of the Flange?

Derailer rear wheels should be laced with the trailing spokes running up along the inside of the flange. There are three reasons for this:

  1. The spokes are bent around each other at the outermost crossing. Under drive torque, especially in low gear, the trailing spokes straighten out and the leading spokes bend even more. If the wheel is laced with the trailing spokes on the outside of the flange, the crossing gets pulled outward toward the derailer cage, and in some cases will actually hit against the derailer under load.
  2. If the chain should overshoot the inner sprocket due to the derailer being mis-adjusted or bent, it is likely to get more seriously jammed between the spokes and the freewheel if the spokes slant so as to wedge the chain inward under load.*
  3. If the chain should overshoot the inner sprocket, it may damage and weaken the spokes it rubs against. Since the trailing spokes are more highly stressed than the leading spokes, it is better to protect them from this type of damage by keeping them inboard.

It really doesn’t matter which way you go on the left side, but if you have all the trailing spokes face inward it makes lacing the wheel a bit easier.* In the case of fixed-gear or coaster-brake wheels, it is better to lace the opposite way, because a derailed chain is more likely to get jammed by backpedaling in these cases.

Note: This is not an important issue! There is a sizable minority of good wheelbuilders who prefer to go the other way around, and good wheels can be built either way.

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