Lacing 40 spoke wheels – z1,z900/z1000
This tutorial is on how to lace a Kawasaki z1000 spoked wheel it is applicable to most if not all the Kawasaki series z1/z900/z650 wheels and the process pretty much applies to most road bikes with spoked wheels, keep in mind the hole count may vary and the cross over pattern might be different on other models.
The Kawasaki z1000A1 and z1000A2 models feature a rear disk mounted to a different hub to the earlier drum brake models. The disk hub features 40 spokes in total, like the earlier models but 20 spokes are <TODO-MEASURE)mm in length while the remaining 20 spokes are <TODO-MEASURE>mm in length. Also note that the shorter spokes are 2 distinct styles with slightly different bends in them, so the side they orient on is critical but easy to determine as they will not point in to the centre of the rim if you poke them into the wrong whole.
A 1976 z900-A4 also has 40 spokes, all the same length (<TODO-MEASURE>mm). In fact most Drum Brake hubs have equal length spokes. I have also discovered the z650B models have the same front wheel as the z900-A4 but the rear wheel has a different sized drum so the spoke set is different to the z900-A4.
On the z1000 (and most “z” series bikes), the lacing is done so that 10 spokes are laced per edge. There are 4 edges, 2 on the chain side and 2 on the disk side. Each side has an “outer” edge and an “inner” edge.
On the Rim there are ridges that match the orientation for the spoke so the nipple seats evenly in the rim, if you poke a nipple into any hole you will quickly see the direction it points, the holes are in pairs and each pair points to a side of the Hub while the next two holes point to the other side but in the opposite direction. This is typical of most Japanese motorcycles but there are always exceptions to the rule!
To lace the spokes in, separate the spokes into 3 groups, each group has the same size spokes, so 2 short groups and 1 long group in the case of the z1000. On a drum brake model there would be 4 groups and all the spokes would be the same size but will have different bends for the “inner” and “outer” spoke.
Mounting the hub
You might find it easier to mount the hub on a shaft and secure the shaft into a vice so the hub is horizontal. This gives you easy access to the hub for putting spokes in. If you can’t manage this, then a flat bench will be required and best to put a towel down so the rim is not scratched or damaged on the bench. If mounting on a vice, put the chain side towards the vice. If using a bench then just start with the chain side up and flip it over when all the spokes are installed.
Lacing the Outer Edge (Chain Side First)
Find a hole in the rim where the valve stem pokes through, use the first spoke nipple hole to the Right of it that is pointing to the chain side inner edge. We will make this spoke the first and it is called the “Key” spoke.
When installing the spokes, work in a Clockwise direction from now on. Once you have installed the first “inner” spoke, count the next hole in the RIM as 2, then 3, 4 and finally 5. Place a nipple in 5 and feed a spoke from the hub to it (remember every second hole on the HUB). Screw the spoke in till the last thread can be seen. Rotate the hub as needed so the spoke extends its full length.
Now looking at the RIM where we just screwed in the, count Holes 2, 3, 4, and stop at 5. Hole 5 is the next spoke hole for the edge we are doing, this hole will become our #1 hole when we count out the next spoke. That means we should have 3 empty holes between each spoke so far.
On the hub there are 20 holes, 10 for the outer edge spokes and 10 for the innner edge spokes. Install the remaining inner edge spokes, then start on the outer edge spokes. Once that’s done, flip the wheel over.
Trial fit the first long spokes, You should be able to see the spoke reach the rim and meet a nipple pointing in the same direction. You can either do them in a clockwise direction first and then do the remaining spokes or do them in pairs.
The photo below shows the counting sequence in case you are stuck. As there are 4 spokes in a group, we count 1 to 4, but when you go to install a spoke of the same edge and type, count 2, 3, 4, then 5 The 5th is the start of the next group so 1 and 5 are used but mean the same spoke. Using our new #1 hole, count 2,3,4, and then 5 and repeat from here till all 10 spokes are in. Just remember that each time we count to 5, #5 becomes our first new hole for the next group.
If the hub is loose then every spoke will need to be tighten an equal amount so the Hub is tight.
Truing and adjusting the tension
Truing the wheel allows it to rotate evenly for its entire rotation. Tension means it will support the weight of the bike during its full rotation without buckling.
To achieve this we need to mount the wheel in a stand so we can spin it freely and check it is laced true and correct for both side to side movement while rotating and has equal distance from the centre axle up and down.
You will need to either buy or build a stand to mount the wheel so it can be spun as if it was spinning on the bike. Professionals use cones that push into the holes where the axle spins to support the wheel. A dial gauge is required to get the alignment exact but if you don’t have a dial gauge you can use a rod mounted at rim height to visual spot the rim’s side to side movement.
Assuming you have the wheel mounted, spin the wheel and note the side to side movement. Locate the edge that comes closest to the rod and visually note the edge that is furthermost. Somewhere in the middle is where we want to centre the wheel on. If you use a dial gauge you can re-zero the gauge on this point and then adjust as per below till you are as close to the zero point as possible. As a rule of thumb, within 2mm is considered acceptable for a lot of rims, best to check the service manual for your exact model.
Where the where rolls closest to the rod, tighten the spoke on the opposite side for approximately 4 spokes, that’s 2 before the low point and 2 after the low point, try 1/8th to 1/4 turns only and spin and repeat. You may need to loosen 2 to 4 of the spokes 180 degrees around from the low point if you have reached the tension point of the nipple.
If the widest point has not altered, stop the wheel at that point and tighten the spokes on the side of the rod, again 2 before the wide point and 2 after. Roll the wheel additional times and adjust till the wheel’s side to side movement is reduced to nearly zero.
Now move the rod under the rim so that the gap from the wheels low to high point can be measured.
To tension the spokes, tap each spoke and listen to its note, under tension the spokes should “ring” otherwise they will make a thud noise. You can use a torque wrench and torque all of them to the correct torque but tensioning by ear is a well used method.
When tensioning with a torque wrench, check the service manual to make sure you set the tension to the right setting. Tighten ever 4th spoke so you don’t change the side to side run out.