Condensed answer: Bike spokes can be shortened. The first step is to cut them to length. The second is to file the ends and re-thread them.
Step 1: Cutting the Spokes
Before cutting the spokes, one first has to make a correct calculation of how long they should be for the new wheel.
The most common method is to use an online spoke calculator which requires the following data:
- The wheel type (front or rear)
- Disc or rim brake wheel
- The total length of the hub
- Hub diameter
- Gear and non-gear side length
- Rim thickness
- The inner diameter of the rim
- Number of spokes on the wheel
- Number of crossings on the non-gear side
- Number of crossings on the gear side
Once you know the needed length, subtract it from the total spoke length, mark the difference and cut it.
The recommended tool for cutting a spoke are heavy-duty pliers.
I like using pliers designed to cut gear and brake cables. They work well for cutting spokes too.
It’s advisable to wear eye protection when cutting spokes with pliers because metal pieces may fly away. If you’re strong and don’t need both hands to close the pliers, you may also hold one end of the spokes with your free hand to prevent it from jumping at you.
Another option is to cover the spoke with a rag while cutting it. The rag will stop the cut pieces from flying away.
Alternatively, you can use a hacksaw, but it will make the process a lot more difficult and longer. You will also need a vise to secure the spoke.
After cutting the spokes, file the rough edges until the end is as flat as possible.
Step 2: Re-threading the Spokes
Spokes are secured to the rim via nipples which thread onto the spokes’ ends.
To thread the spokes, one needs a special “spoke thread rolling machine“.
You cannot re-thread a spoke with any other tool because spoke threads are “rolled in” rather than “cut” in.
Or in other words, there’s no material loss. To make the thread, the machine presses the metal into the spoke.
This is done to prevent material loss and preserve the strength of the spoke. Conversely, a basic cut threading wastes material and hurts the integrity of the spokes.
Spoke threading machines tend to be fairly expensive (USD 200+), especially if you want a high-end one.
If you’re working on a single project, and you don’t plan on using the machine again, it will make more economic sense to either pay a bike shop to do the threading or buy new spokes of the correct length.
Note: Some people prefer to first make the new threads, and then cut the spokes to the desired length.
In that case, the process is as follows:
1. Make a long thread.
2. Screw a nipple onto the spoke all the way down.
3. Cut the excess with a set of cable cutting pliers
4. File the edge.
5. Unscrew the nipple to clean the threads from debris.
Z Bend Spokes For Emergencies
The main reason for cutting spokes is to make units of a custom size. However, cutting spokes is also useful when creating Z bend spokes for emergencies.
Regular spokes are J bend. Z spokes, on the other hand, have an end resembling the letter “Z”
Z spokes are no longer popular, but they can be useful when a J spoke of the right side is not available.
The main advantage of a Z-spoke is that it can be used to replace a broken spoke without having to remove even the tirе.
Instead, one just unscrews the broken spoke from the nipple, wiggles the Z spoke into the hub and then threads the nipple via a spoke wrench.
It’s possible to make a Z-spoke out of a long J spoke.
The process is as follows:
- Cut the J bend (non-threaded end) of the spoke.
- Mark how long the spoke should be and then make a 90-degree bend a few millimeters before the marked spot.
- Make another 90-degree bend a few millimeters after the initial one. Ensure that the second bend is parallel to the marked spot. This will be the part that acts as a stopper/elbow.
To do a perfect bend, it helps to have a set of good Z-bend pliers. However, if you’re not doing that procedure that often, a pair of regular or needle-nose pliers will do.
In an emergency, one can also use a multi-spoke wrench as a jig to make the bends.
Note, that you will have to do the bends more than once because each bend will get straighter after making the next one.
Nonetheless, it’s still possible to come up with an acceptable Z bend by using just a spoke wrench.
Summary: What You Need To Know
1. Bike spokes can be shortened. One can use the following tools for cutting spokes:
- Heavy-duty pliers
- Pliers for cutting bicycle brake and gear cables
- A hacksaw
- A Dremel
Pliers are the fastest, quietest and do not leave a metal residue.
The cut end of the spoke has to be filed.
2. Once cut, the spoke has to be re-threaded. The procedure requires a special machine which creates threading by pressing the material into the spoke (rolling it in) rather than cutting it. This is done to preserve the diameter of the spoke and subsequently its strength.