Each Shimano part has a unique code that helps to find the right replacement. If the part number doesn’t match then the components won’t be compatible. We will endeavour to have shimano parts numbers explained to you in the following article.
Items to help you with the job.
Cloth.
Some model numbers might be covered with dirt and grease so wiping with a cloth might help to make it more visible.
Torch.
Model numbers are small and etched in hard to reach places, so a bright light will make them more visible.
Shimano parts – brake lever
This model number starts with BL which stands for brake lever.
On flat bars it is usually on the underside of the lever body. 
Hydraulic levers have the model number either etched under the lever body or printed near the reservoir.
On drop bar levers the code is etched on the side of the lever blade hidden inside the lever body. To find it pull the lever.
Shimano parts – Gear shifters
The code starts SL which stand for shift lever.
On flat bars it is etched near the handlebar clamp bolt or under the body.
Revoshift shifters have the code on the underside of the lever near the clamp. 
Drop bar shifters have their code etched on the side of the body.
Integrated brake and gear levers.
These are called STI levers. This stand for Shimano Total Integration and the code starts ST.
On flat bars they are found either under the lever body or near the barrel adjuster. 
On drop bars the part number is usually marked under the hood on the lever body. Lift the hood from the bottom and if necessary, check under the handlebar tape near the lever body.
Some hydraulic STI levers have their model number etched inside the plastic gear lever blade. 
Brake Calipers
The model number starts with BR. This stands for brake.
V brake calipers will have the model number on one of the arms at the back of the caliper body behind the springs. If you can’t read it then you will need to release the spring. First release the v brake. This will loosen the tension on the spring. If your not sure how to do this our video here will help you with this task. Now unhook the spring. If you still can’t see it you might need to remove the brake pad.
If you need help with brake pad removal and replacement then our article here will help you with this task.
You can also watch our video tutorial here:
The model number doesn’t indicate the colour so when buying a replacement using this model number you will need to chose the right option.
Dual pivot calipers have the model number etched either at the back of the caliper or printed near the barrel adjuster. 
The model number doesn’t indicate the colour. When buying a replacement using this model number you will need to chose the right option.
Disc brake calipers have the model number etched near the caliper fixing screw or printed in the centre of the calliper.
Roller brakes are coded on the inside of the arm.
Rotors
The model numbers starts RT for disc brake rotors. In some cases the part number will start SM for other parts.
The part number on disc rotors is etched either on the lockring or the silver part of the rotor.
The variations within the model number are the rotor sizes which are usually between 140mm and 203mm.
Hubs
The model number is written on the middle of the body.
The front hub starts with HB which stand for hub.
The rear starts FH which stands for freehub body hub.
Some wheel hubs will have a number starts with WH (for wheel) this means that the hub is a part of a Shimano built wheel.
If it is a dynamo hub the model number will start DH for dynamo hub.
The model number for a hub gear hub will start with SG ( internal gear hub).
Be aware, that within the model number, there will be alternatives. The model of your hub might have options for the number of spoke holes, e.g. 32 or 36 hole, different colours, e.g. black or silver, for hub gears a choice of brake mounts, e.g. disc brake or roller brake, and for thru axle hubs different axle lengths, standard or boost.
Shimano parts – Chainset
The model number starts FC for front chainwheel.
The most common place to find it is near the pedal hole but sometimes it is stickered along the centre on the inside of the arm. 
Be aware that there will be variations within the part, such as colour, e.g. black or silver, crank arm length (written in millimeters and varying between 160mm and 175mm. ) and the number of teeth on the chainrings.
The left crank may have more than one model number. This indicates that it is interchangeable between these parts.
The model number number doesn’t indicate variations such as colour and crank arm length.
Shimano parts – bottom brackets
Shimano bottom brackets will have a model number starting BB for bottom bracket.
It is printed on the outside bearing shell for Hollowtech II.
Cartridge bottom brackets have the model number written on the shell inside.
Press fit bottom brackets have the model number etched on the face of the outside bearing shell.
For the Hollotech 11 mountain bike model there are two shell widths 68/73mm and 83mm within the model number.
Cartridge model number doesn’t indicate the shell width (68mm and 73mm) and the axle length (107mm-127.5mm). There are no variations on the press fit.
Chain
The chain model number starts CN for chain and is written generally on every other link. For 10 speed and above, the writing will only be on one side.
Freewheels and cassettes
The model number for a freewheel starts MF (multiple freewheel) and is stamped on the biggest cog.
On the 7 speed freewheel the model number doesn’t indicate whether it is 14-28 teeth or 14-34 teeth option.
The model number for a single speed freewheel starts with SF which stands for Single Freewheel. It doesn’t indicate the number of teeth on the sprocket.
For cassettes, the model number starts CS . It is either written on the largest cog or on the lockring.
There are variations on most models concerning the number of teeth on the smallest and largest cogs.
Rear derailleur
The model number starts RD. This stands for rear derailleur. It is etched on the back of the derailleur body.
The model number doesn’t differentiate between the cage lengths (SS(short), GS (medium), and SGS(long) and colour (silver or black) and the colour (black or grey).
Front derailleur
The model number starts FD for front derailleur. It is usually etched behind the back plate of the cage. Sometimes the model number will be etched at the bottom of the derailleur body near the clamp.
The model of your front mech may have options for how it is attached to the frame (band on, braze on, direct mount, E-type, Mid Clamp Mount Boost or Mid Clamp Band Mount), the size of the clamp band (S/M – 28.6mm/31.8mm and L – 34.9mm)
the position of the cage in relation to the clamp (swing) (top swing, bottom swing or side swing), the angle of the derailleur in relation to the chainset (either 63-66 degrees used on hybrid bikes or 66-69 degrees for mountain bikes) and if it can shift 2 or 3 gears.
You can also watch our video tutorial here:
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