What are cottered cranks?
Installing cotters You might have to replace the bottom-bracket spindle too. French cottered spindles have a diameter of 15.5 mm (0.610″) and most others, 0.625″ (5/8″). The flat on a cotter is at an angle to the centerline of the cotter.
What is a cottered crank?
Many older bicycles use wedge-shaped fasteners called “cotters” to hold the cranks onto the bottom bracket axle. These cotters have a nut to hold them in place after they have been driven or pressed in. They can be difficult to remove, especially if they have been in place for a long time.
How are Cotter cranks supposed to be installed?
When installing cotters, they must face in opposite directions so that the angles of the flats will cancel out and the cranks will wind up 180 degrees apart. Some older books speak of installing the cotter so that the pedaling load is taken by the thick end of the cotter.
What kind of punch to use on a cotter crank?
My favorite punch for this purpose is an old pedal spindle with the thin end ground flat. These spindles are made from the same superior kind of steel used in good tools. They are thick at the end you hit, but they taper down nicely to a size that will fit into the cotter hole of the crank.
Which is the best tool to remove cotters?
But I’ve found that a 16- or 20-ounce claw hammer (carpenter’s hammer) is better than the ball peen or sledge in removing cotters. A claw hammer usually has a more-nearly flat striking surface, and its face is angled advantageously for removing cotters.
What’s the best way to remove a Cotter on a bike?
Fortunately, the most common tool to remove cotters is one found in just about every household: the hammer. To drive out a cotter that’s been properly installed requires one or two very hard hammer blows. This can be tricky, because unless you take careful aim, you can severely damage other parts of your bike.