LewTwo
1 MW
According to the Elephant Bike site referenced earlier the Royal Mail Bike has 26x1-3/4 inch rear tie and an a 24x1-3/4 inch front tire. They also make reference to 3 speed hub gears with a trigger shifter. Considering the age and provenance of this design that surely has to mean a British made Sturney Archer internally geared rear hub (IGH). I am also going to go out on a limb here and predict it has British threaded bottom bracket.
Brakes:
There are two predominate schools of thought on brakes. Some people prefer disk brakes and maintain that they are superior to rim brakes. The other side prefers rim brakes and feel that they are superior to disk brakes. Personally I prefer to think of rim brakes as disk brakes with a really big rotors.
Caliper rim brakes (single or dual pivot) can be installed on most bicycles because they only require a single mounting bolt for each wheel that just happens to be where the fenders mount as well. Most bicycle frames have these two mounting holes incorporated into their frames.
Other forms of rim brakes ("V" brakes, "U" brakes, cantilever brakes, roller brakes) require two pivot pins that are typically welded to rear seat stays and the fork blades.
Disk brakes use a rotor that is attached to the hub. A caliper "squeezes" the rotor to stop the wheel. The caliper in this case is attached to the fork or the rear triangle via a special mount that is most often part of the frame design design. Aftermarket caliper mounts may be welded or bolted to the frame or fork.
There are also a some other brake types such as drum brakes, band brakes, spoon brakes. People have been riding bicycles for more than a century and during that period they have tried nearly every method of stopping a bicycle that can be imagined. Running into a masonry wall is probably still the most effective though painful method.
Brakes:
There are two predominate schools of thought on brakes. Some people prefer disk brakes and maintain that they are superior to rim brakes. The other side prefers rim brakes and feel that they are superior to disk brakes. Personally I prefer to think of rim brakes as disk brakes with a really big rotors.
Caliper rim brakes (single or dual pivot) can be installed on most bicycles because they only require a single mounting bolt for each wheel that just happens to be where the fenders mount as well. Most bicycle frames have these two mounting holes incorporated into their frames.
Other forms of rim brakes ("V" brakes, "U" brakes, cantilever brakes, roller brakes) require two pivot pins that are typically welded to rear seat stays and the fork blades.
Disk brakes use a rotor that is attached to the hub. A caliper "squeezes" the rotor to stop the wheel. The caliper in this case is attached to the fork or the rear triangle via a special mount that is most often part of the frame design design. Aftermarket caliper mounts may be welded or bolted to the frame or fork.
There are also a some other brake types such as drum brakes, band brakes, spoon brakes. People have been riding bicycles for more than a century and during that period they have tried nearly every method of stopping a bicycle that can be imagined. Running into a masonry wall is probably still the most effective though painful method.
