Why Does My Rear Derailleur Keep Hitting My Spokes?

Riding a bike is an excellent way to get fit and enjoy the outdoors with other like-minded people. Cycling can take you pretty much anywhere, provided you have the enthusiasm and drive to keep pedaling.

One thing that does come with cycling, which many of us don’t always account for, is having the odd issue with our bikes.

Bikes are amazing machines but have a very tough job to do. They must be lightweight, functional, and tough enough to take hits from the road. Like a vehicle, every so often, you might have a problem.

A common issue many cyclists have is that the derailleur keeps hitting the spokes when riding. This article will explain why this happens and how to fix it.

Why does my derailleur keep hitting my spokes?

Derailleurs must be perfectly in line, and if they are not, your bike isn’t going to work as well as it could. If you find your gears don’t work well or the chain is regularly skipping, it is more likely that this chain line isn’t correct.

The reason your derailleur will hit your spokes is that it isn’t where it should be and is leaning too far inside the wheel, so when you go into your lower gears, you start to hear a ting.

Why does my chain line move?

So we know the reason the derailleur is hitting the spokes is that the chain line isn’t correct, but why does the chain line move? There are many reasons why this might happen, but here are the most common.

Bent Derailleur Hanger

The most common issue to cause an incorrect chain line is a bent derailleur hanger. A derailleur hanger, or mech hanger as it is commonly known, is a small piece of metal that sits between the rear derailleur and the bike’s frame. Most derailleurs are unique to each bike or brand of bikes and can be challenging to get hold of.

The mech hanger is normally made of aluminum and has a very important job. It is designed to be strong enough to maintain the chain line but also has to be weak enough that when the derailleur is hit, it will bend.

It’s much cheaper to replace a derailleur hanger than to buy a new derailleur. When the mech is bent, it causes the chain line to lean inwards and hit the spokes.

Bent Derailleur

If the hanger isn’t bent, then more than likely, the derailleur will be bent. Sometimes you might find after a fall, or if something has hit your bike, it can cause the derailleur to bend.

This can have the same effect as the mech hanger being bent and cause the derailleur to lean in and hit the spokes.

Broken Derailleur

The next issue you might have is the derailleur itself is broken.

It is very common for derailleurs to break and what can happen is the derailleur loses its adjustment, and then because it is poorly adjusted, it goes too far into the spokes. This could be something as simple as a loose screw or a broken cable.

How to stop your derailleur from hitting the spokes

So now we know what causes the problem. How do we go about fixing it? Here’s our step by step guide to identifying the problem and fixing it.

Step One: Inspect the derailleur

You first need to look at the derailleur and see if it has any broken parts or looks like it has taken any damage. If it has damage, that will likely be the issue.

Step Two: Check the Chainline

The next step is to check the chain line. It would be best if you stood by the bike on the drive side to do this. Then look above the chain and inspect the chain line to see if it runs straight from the front chainrings to the rear cassette. If it looks like it is twisted, then the mech could be bent.

Step Three: Fixing the problem

If the problem is a broken derailleur, this will need replacing, and we recommend replacing the mech hanger and the cables simultaneously to ensure that you won’t face problems later down the line. Add the new derailleur and adjust the screws to suit your cassette.

If your derailleur is fine but you’re still having issues, we recommend replacing the mech hanger. Mech hangers can be repaired if bent, but once bent are much weaker and might cause more issues later down the line. Once done, you will need to adjust the derailleur again to suit your cassette.

Conclusion

If you find your rear derailleur is hitting the spokes, it needs fixing as soon as possible. If you avoid this repair, it can lead to multiple problems, such as a broken wheel or damage to your frame.

Typically, your mech hanger or rear derailleur will be causing the issue and can be fixed at home or easily sorted at a local bike shop.

Robbie Ferri

Robbie Ferri has spent years working in a bike shop, has worked with industry leading brands on product creation, has been a semi pro athlete, and is a fully qualified strength and conditioning coach. He has broken World Records, bikepacked all over the World and raced ultra distance at a top-level.