There are many ways a chain can rub. The most common is undoubtedly the friction of the chain between the chainrings and the frame. For those who confuse chainrings and sprockets, a chainring is a set of sprockets on the crankset in terms of a motorcycle. Lately, chainrings and cranksets have become somewhat synonymous. In this article, we will explain to you why a motorcycle chain rubs?
Motorcycle chains - General information
On the market, there are a whole bunch of motorcycle chains that meet specific needs. So, before you get started, we advise you to take a look at our complete guide on the subject.
A motorcycle chain that rubs because of a problem with the derailleur screw
The derailleur limit screws are vital points in any drivetrain. If they are not set correctly, many items can be damaged. Fortunately, they are not that difficult to fix.
More precisely, for a problem with a motorcycle chain which rubs between the chainrings and the frames, we must check if the “low” screw limiter of the front derailleur is correctly adjusted. Sometimes an "L" will mark it. If not, you can check the manual for that derailleur online or determine which of the two screws is the correct one by turning them and observing the movement of the derailleur.
It basically limits how far the derailleur can travel to the left, or in other words, to low (easier) gears. A rule of thumb is to adjust it so that the inner plate of the derailleur cage is 0,1 - 0,5mm from the chain when it is on the smallest sprocket. This way the derailleur will prevent the chain from falling off and getting caught between the chainrings and the frame.
If this configuration is correct, then you should look for another potential problem.
Derailleur limiting screws available on Amazon
A motorcycle chain that rubs because of a bent sprocket
This problem is a little more familiar with motorcycles that have sprockets have a greater difference in the number of teeth. The bigger difference in teeth means a bigger difference in size. As a result, the front derailleur is too far from the smaller sprocket to hold the chain in place. If the pinion is straight, everything should work fine. However, if the sprocket is not aligned properly with the larger ones, the chain may fall off during the shifting.
We do not recommend trying to fix this problem unless you have some experience in servicing motorcycles. If you decide to try, you should remove the chain from the motorcycle and try to straighten the sprocket by force. A hammer or a good pliers can help. Be careful not to bend the teeth during the process.
A stuck chain link can cause a motorcycle chain to rub
If a chain link is completely stuck, you will probably find it out some other way. However, sometimes the chain links are only slightly jammed, preventing them from straightening out.
In practice, this phenomenon is similar to chain wear or pinions. The chain links do not line up properly with the teeth and the chain occasionally falls or hangs.
How to repair the chain?
Usually you can repair the chain, but it takes a little force and can damage the paint. We will start by slackening the chain. You can achieve this by moving the derailleur forward. It is important to do this, otherwise it will pull on the chain you are trying to free.
Your best bet is to remove the smaller sprocket, which sits right next to the frame. It is held by four bolts, accessible on the inner side of the small ring. You can easily remove the bolts one by one while the crank is still on the motorcycle. This should allow enough play in the sprocket itself to pull the chain out of there. This is the first thing I usually do, but if you can't crank the crank to access enough bolts, you may have to try something else.
We therefore have option 2, remove the crank. Cranks do not remove themselves by simply removing the bolt. Removing the entire crank requires a keyless crank extractor tool. The tool is quite simple to use. Thread the larger thread into the crank arm, then thread the thinner part of the tool, which will push on the axle. With the right tool and the knowledge available, you probably would do it right away.
Remember to tighten all the bolts. This is a great opportunity to get rid of all traces of rust. You can add some fat to each of them.
If the chain keeps falling off the inner chainring, you should check it. A tooth may be bent, the chainring is worn, or the derailleur limit screw is not adjusted correctly.
Our recommended products for a motorcycle chain that rubs:
To conclude, here are some recommended products on Amazon:
