Mountain Bike Parts 13 - 24

13. Idler Pulley - mountain bike parts

The idler pulley is the bottom portion for the rear derailleur that provides spring tension to keep the chain tight.  If you get a flat rear tire and need to replace the inner tube, you can release the chain from the chain rings by pulling this part forward (toward the front of the bike). 

Also, you can manually release the tension of the chain to put your chain back on if it comes off while riding.  Remember, if your chain is coming off a lot, chances are it's stretched out or worn down and you'll need a new one.

14. Nipple - mountain bike parts

On mountain bikes, the nipple refers to the small threaded nut that fasten the spokes to the rim.  On some tires, the nipples are located at the hub to reduce the moment of inertia.  The reason these tiny parts are mentioned is because they are used to adjust the tension of the spokes when they get out of adjustment.  Off-road riding can loosen some of the spokes which causes the rim to warp.     

15. Pedals and Shoes

The pedals connect the rider's feet to the bike, as do the handlebar grips.  There are different kinds of pedals, some requiring special shoes.  For more information on mountain biking pedals and shoes click here.

16. Rear Suspension - mountain bike parts

The bike in the model above is a hardtail mountain bike, so it does not have rear suspension (aka. full-suspension).  Rear suspension receives the most technological attention, and therefore there are several rear suspension designs including:

• Soft tail
• Single pivot
• Unified rear triangle
• FSR system
• Virtual and  pivot point
• Monolink
• Equilink    

If you are looking into buying a new bike and can't decide if you want to buy a hardtail or full-suspension bike, click here.

17. Rim - mountain bike parts

The rim is the metal ring that supports the inside of the tube and tire, and it's also what holds the spoke tension.  Bikes that use rim brakes require smooth parallel rim-walls for an adequate braking surface.  Bikes that use disc brakes do not require this braking surface since they utilize the disc mounted on the hub of the tire.

Are you braking wrong?

18. Saddle

The correct term is 'saddle' although many people call it a 'seat'.  Technically, a seat supports 100% of a person's weight, like with a recumbent bike seat or even a car seat.  A saddle can support the weight of a rider but it often goes unused; like when you stand to peddle uphill, descent rough terrain, or when braking hard.  Although somewhat obvious, it's named after a horse saddle. 

This part is adjustable in height and in slant, so make sure you fit your bike to your riding style and preferences.    

19. Saddle Post

The saddle post attaches the saddle to the bike frame.  Adjust the height of your saddle by raising or lowering this post (aka tube).  Most mountain bikes use a quick release lever to adjust the height of the saddle so that adjustments can be made without using any tools. 

20. Skewer

A skewer is a metal rod that goes through the hub of the tire.  It attaches the tire to the frame's dropouts (pictured right).  Most mountain bikes use a quick release lever to attach and detach the tire from the bike without using any tools. 

21. Spindle - mountain bike parts

The spindle is actually a part of the bottom bracket.  It is the axle inside the bottom bracket that spins using ball bearings.  Both crank arms attach to the spindle.

22. Spokes - mountain bike parts

The spokes are those wires that attach the rim to the hub of the tire.  If the spokes get out of adjustment, they can cause the rim to warp.  A warped rim causes braking problems (with rim brakes), inefficient pedaling, and other problems that effect your balance.

23. Stem - mountain bike parts

The stem is what holds the handlebars to the steer tube.  It is also called a 'goose neck'.  Depending on the length of your arms, you may want to consider purchasing a longer or shorter stem so that you fit your bike better. 

If your stem is not the right length, you will experience back pain that is not necessary.  Threadless stems are standard on mountain bikes making them easy to replace if need be. 

24. Wheel Hub - mountain bike parts

The center of the wheel is the hub.  The frame's dropouts and spokes attach to the hub.  Also, the back tire has a sprocket or sprocket-set that is installed on the hub of the tire that makes it possible for the chain to run on. 

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