What combinations on a 7x3 would be cross chaining?

You will receive a “Bike Owner's Manual” if you buy bicycles of reputable brands. If you do not have one, just google “Bike Owner's Manual” to find one.

If you take a look at page 6 of “Bike Owner's Manual” supplied by Apollo, you will see a diagram on “Recommended Chainwheel/Rear Sprocket Gear Combinations”


Chain crossing will wear out your chain and damage your drivetrain sooner than it should. So, avoid setting your gears so that your chain sits on the chainring and sprocket as marked “X” on the diagram.

Customers who buy bicycles with gears from Jom Johan will be given a chart to advise how gears should be used for efficient cycling and to prevent drivetrain from being damaged any sooner than it should.

Clattering sound when cycling?

If you hear a clattering sound when you are cycling but don't see anything stuck on your chainrings, that could cause the noise when you checked, it is likely the sound of your chain rubbing against your derailleur.

To verify if that is the cause, check where your gears are at when the noise starts.  Is your chain sitting on the larger chainring while the other end is sitting on the largest ring of your cassette?  If it is, look at your rear derailleur.  You will notice that it is stretched way forward.

If your chain is sitting on the smallest chainring while the other is sitting on the smallest ring of your cassette you will noticed that the rear derailleur is stretched way backward.  That means that you are cycling on extreme gear combinations and the grinding noise you hear is the chain rubbing against your rear derailleur.

This cross chaining process puts the chain at too much of an angle which adds tension and can cause your chain fall off the bike and wears it out faster than it should.

So now you know that you should avoid the following combinations:
Front gear is at 1 while back is at top gear
Front is at 3 while back is on lowest gears

Watch this video and you will have an idea of what I am talking about.