The Back Wheel Wobbles on a Bike (Possible Causes)

Ever had the experience of the back wheel on your bike wobbling? It’s probably the case if you are
reading this article. We are going to look at the possible causes of this issue.

A couple of issues can cause the rear wheel to have that slight wobble: the manufacturing process of
hubs, an improper number of bearings, loose cup-and-cone bearings, or the wheel is slightly buckled.

The wobble can be a vertical one due to the wheel being oval than it is circular.
By taking off the wheel, holding it by the axle, and rotating it you should be able to drop some probable causes. Ideally, the wheel should have no other movement besides the rotation/spinning

Diagnosis of a Wobbly Wheel

Remove the free wheel taking care not to strip the notches on the axle. Measure how much of the axle is sticking out and try to make it even on both sides. Check the cone and axle for any warp, the bearing for wearing.

Greasing and replacing the bearings is a good start, then the axle too as you reassemble the free-wheel after that, you can check again for the wobble. Make sure to tighten your hub cones so there is no play but also so there is no binding otherwise it will make for a difficult ride.

Truing a Bike Wheel

Assuming the wheel is cylindrical; if the wobble persists,it might be that the spokes are pulling tighter to one end causing a section of the wheel to warp to one side. Use a marker right next to the brakes to determine the section with the warp. Tighten the spokes on the side you want to move the rim towards and loosen the spokes on the side you want to move them away from using the right spoke wrench. Work the spokes in pairs tightening and loosening sequential sets. Truing is harder without a truing stand but not impossible, just a little difficult and time-consuming. By plucking the spoke you can determine, from the sound whether the spoke in that are needs adjusting or not relative the spokes surrounding it. The advantage of a truing stand is it is easier to work out the part of the wheel causing the wobble. And making the adjustments to both sides of the wheel is faster and simpler even. When dealing with a radial wobble, the slight up and down wobble in your rear wheel, it is advisable you check for and fix any lateral wobbles first. Radial wobbles are about the general tension on the wheel as a whole. By spinning the wheel with a marker below it to make contact and note the elongated sections on the rim. You can then get rid of them by tightening the two spokes that are on either side of the marked area. After every turn at tightening, spin the wheel again with the mark to check for contact. Make sure that there are no internal deeps or flattening on the opposite of the area you working on.

When the wheel will not stay true and there is visible warping on the rim, if there are loose or missing spokes, the rim might be shot and it has best to get a new wheel at this point. In the less extreme circumstance though just replacing the spokes would do the trick. It is also a good practice after truing to check for and tighten any extra-loose spokes and fine-tuning adjustments.

Make sure the wheel is slotted in perfectly relative to the frame, brakes, and gear components. In the case that you have to replace the spoke, make sure the new one is of the same exact length and thickness as the one you are replacing.

Insert the head of the spoke in the hub, curving it away from it, bending the spoke a little to get it in place but do not bend it sharply. Once in place, put the nipple end through the hole in the rim, threading carefully to the end of the spoke. Use your hand to tighten the nipple, using a wrench could damage the spoke or overly tighten the spoke.

For more visual aids, Global Cycling Network offers quite a helpful catalog of tutorials and fixes to assist with issues such as these. Joining the Bicycles community on StackExchange is also helpful. A rear-wheel wobble can be a simple irritation or dangerous in heavy traffic it is best to have it sorted as quickly as possible.