Published on October 14th, 2016 | by Greg O'Keeffe
Ask a Mechanic | Replacing a Broken Spoke
Louis asks, “I recently broke a spoke on my rear wheel and am slightly confused about how to replace a single spoke on a wheel. Any advice?”
If you ride long enough, you will eventually break a spoke. Unfortunately there is no predicting when or how a spoke will break. It could break in the middle, at the nipple, or at the head. Although there is typically very little you can do while on the ride, replacing that broken spoke isn’t all that difficult.
The first thing you’ll want to do is remove the old, broken spoke. Unless you’re dealing with a UST rim, you’ll need to remove the tire and rim strip. And if you’re dealing with disc brakes, go ahead and remove the rotor. Should the broken spoken be in the rear wheel, you’ll also need to remove the cassette. This will make things much easier when it comes time to put the new spoke into the wheel.
Once the wheel is effectively stripped of all it’s components, you can remove the old broken spoke from the hub. Next you’ll want to measure for the length of the replacement spoke. If the spoke broken at the nipple or head and is still in decent shape you’ll be able to get an accurate measurement from the old one. If the spoke broke at the nipple and there are no threads just take the measurement to the base of the threads and add 10mm.
If the spoke broke somewhere in the middle it will be a little tougher to get an accurate measurement. The best way that I’ve found to do this is to measure a different spoke on the same side of hub using a soft measuring tape, measuring from the head of the spoke to the end of the nipple and then adding 10mm. You can measure to the edge of the rim where the nipple exits and add 2-3 mm, but I’ve always found the first way to be more accurate, especially if you don’t have a soft measuring tape.
Once you have the measurement for the spoke, you will most likely need to have a spoke cut to that length. If you don’t have a spoke available, give us a call or visit artscyclery.com and we can get one cut for you. Once you have the spoke, it’s time to put it in the hub. Be sure to pay attention to which direction the spoke enters the hub because the spokes alternate between heads up and down for lead and trailing spokes. You may have to bend the spoke a little to get it through, which is fine. Be sure to aim for a large opening in the opposite side of the wheel and not inside of a spoke crossing so you’re able to move the spoke freely once it is all the way in the hub.
Next, follow the direction of the other spokes with the same head up or down orientation, being sure to cross under or over the correct spoke. Now you can thread the nipple onto the spoke. I recommend threading the back of the nipple onto another spoke a few threads and using that spoke to put the nipple through the rim to make sure it doesn’t end up loose inside the rim. As you thread the nipple onto the spoke in the wheel it will come off the feeder spoke.
All that’s left to do is bring the spoke back up to tension and true the wheel. Check the spoke tension on the surrounding spokes and try to bring the replacement spoke up close to the tension of the others. Then begin to true. I always mark the spoke that I replaced so I know which one is the new one while truing the wheel. This way I know if I should be adding tension to that spoke before taking it away from others. Having a truing stand is beneficial, but you can always put the wheel in the bike and true it using a zip tie attached to the seat stay.
A few things to keep in mind: getting a beat up mountain wheel back to true can be a very daunting and tough task so don’t expect perfection. On lower spoke count wheels, getting the tension of the replacement spoke as close to the other spokes on that side will make truing much easier. Be sure to address any major hop in the wheel as best you can, as it is very common for one to develop when a spoke is broken. Last but not least, when purchasing a replacement spoke, it’s best to get a couple extra spokes and nipples for both the drive side and non-drive side of the wheel to save you some time should you end up breaking another spoke.
Get your spokes cut and the information you need at Art’s Cyclery. See ya next week.
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