What Do The Spokes Of A Bike Wheel Do And Its Purpose?


bike-wheel-spokes

 

You are bike commuting to work one day and notice an obnoxious clicking noise on the back wheel of your bicycle. Pulling over to a side curb you find that there’s a spoke detached from the rim, but you don’t worry much and tie the spoke around another to get to work on time. After a week of riding, you later find yourself forking out $100+ for a new bicycle rim from neglecting to get the original spoke fixed. Several spokes on the back wheel have broken which caused the bicycle rim to warp and bend.  

What some cyclist fail to realize is that all the weight of a bicycle with its rider is concentrated on the hub. The spokes hold the hub of a wheel and transfer that weight to the wheel. So the purpose of the spokes is that they allow stiffness in the wheel making the wheel more efficient when spinning.

There is science behind this madness and I encourage you to read on to find out for yourself what purpose wheel spokes serve.  My goal is to explain this purpose, with all its complexity, in the simplest form.

Bicycle Spokes’ Function

 

Remember as a kid, we used wheel decorations like cans and tennis balls in-between our spokes?  Or the time we attached playing cards to the spokes so it would sound like a motorcycle? That was certainly not the wheel spokes’ function.

In fact, if you remove part of the spokes from a bicycle, the downward force on the wheel will cause it to collapse.

The spokes of a wheel under tension brace the rim so when pedaling and breaking, the wheel can withstand the force.  For example, in the early days, chariots and wagons were built on wheels with spokes made of wood to be strong enough to support the vehicle.

These wooden wheels and spokes became too heavy and required a lot of force and power to move them efficiently.

As spokes evolved over time with different materials, they were formed in such a way that not only weighed much lighter but even performed as strong as one solid wheel.

Components That Make Up A Wheel

 

Excluding brakes and reflectors that are on wheels, there are really only a few basic things that make up a wheel:

  • Tire
  • Rim
  • Spokes
  • Nipples – seating that holds the spokes in place
  • Hub

What Bike Spokes Are Made Of

 

The two most common metals used to create spokes on a bicycle wheel are aluminum and steel.  Although some higher end spokes have been made of carbon fiber materials.

Most bicycle wheel spokes are made of steel.  The benefits of having a spoke made of steel are due to the strength, lightweight and ability to withstand the force that it burdens.

Steel spokes are easily threaded to fit the nipples that attach to a bicycle rim and can handle a lot of tension without being stripped.

The forms that steel spokes can come in are stainless steel and regular steel.  They are sometimes bladed, oval, or butted – for example, this is similar to how a flat head screwdriver is round one side and butted or flattened at the tip.

Spokes made of aluminum are one third less dense than steel spokes and that goes for the stiffness too.  They are thicker than steel spokes and require more space in the seating of a rim which makes wheels weaker and less stiff. Also threading an aluminum spoke is not easy as it does not hold up well.

One way to tell the difference between a steel and aluminum spoke is to place a refrigerator magnet against them and look at them very closely.   Steel spokes will have some surface finish on them, aluminum spokes will have somewhat of a dull gray look to them.

If you are going to decide which spokes you want on your wheel, go with the steel spokes on an aluminum rim as it will be stronger and stiff enough to handle the tension being placed on them over the long run.

Do The Way Wheels Are Spoked Matter

 

You ever notice how some wheel spokes run tangent from the hub and then across other spokes while others run radial or straight from hub to the rim?

There is a reason behind this and it really comes down to how well torque is distributed from the force on the bicycle hub to the wheels.  This affects how the wheel may perform under force and tension which aide in offsetting the load.

Terms Defined:

Torque = the twisting force that regularly causes rotation

Tangential = the spokes are weaved together in a three-cross lacing pattern which allows each spoke to brace against another

Radial = spokes are not weaved together and connect straight from the hub of a wheel to the rim without crossing.  This pattern is less likely to withstand the load placed on the wheel compared to the tangential pattern.

So in contrast to the spokes with the radial pattern, it’s necessary to have tangential spokes which perform much better as torque is forced on it thus allowing the wheel to sustain its strength and stiffness.

Difference Between 32 Spoke & 24 Spoke

 

The main difference between spokes of these numbers all comes down to wheel strength.  Wheel strength is going to affect whether your wheel can handle the force and pressure being placed on it.

So spoke count on a wheel varies from the type of bicycle you have from road bikes to mountain bikes or even a cruiser.  Those bike types vary in the amount of tension and force they have to endure. Having a 32-spoke wheel is going to be stiffer than having a 24-spoke wheel.

In addition, having a 24-spoke wheel does not necessarily mean the wheel will be lighter.  To support 24-spoke wheels or one with fewer means that the wheel or rim it supports will have to be heavier.

Some examples of bikes with less than 32 spokes are racing bikes, fixed geared bikes, and custom bikes.

Having fewer spokes on a bike wheel is ideal if the bike used does not have to endure a lot of weight or impact that other bikes such as a mountain or tandem bikes do.

Choosing between a 32-spoke or 24-spoke may not make a difference to you if you are just starting out cycling.  But as you become more conscious of how and where you ride then this will become essential in your decision.

3, 4, 5-Spoke Wheels

 

Unless you are a bike racer or time trialist, 3-5 spoke wheels are not going to be the first choice for you.  Even though they look very cool and have some aerodynamic advantages, the cost (around $400+) of these wheels will turn you off.

3-5 spoke wheels are made out of a composite plastic and are much heavier than regular spoked wheels. Some carbon fiber wheels with this spoke type are much lighter.  One of the drawbacks to having these wheels for daily cycling is that they are not as stiff as spoked wheels and don’t do well in windy conditions.

The greatest benefit to having 3-5 spoke wheels are that they don’t require much maintenance and can be very effective for commuting with its durability.

What Is Wheel Truing

 

This is one basic part of wheel maintenance that is usually missed just as the important role that spokes play in performing under pressure.

Truing the wheel is a process of tightening loose spokes by turning the right spoke nipple so that it is as tight as the other spokes on that side of the wheel.

The main tool used in turning a spoke is a spoke wrench which grips the spoke nipple allowing you can loosen or tighten them to the right tension.

Most people may decide to do this maintenance on their own if they were instructed on the proper way to do this.  If you are not sure about how to true the wheel it is best to leave this alone and allow a bicycle mechanic or professional to maintain this for you.  

Getting the wheels trued right can mean the difference between riding smoothly and effectively to having a wheel that’s wobbly, ineffective and can potentially bend.

Spoked Wheels Vs. Hubless Wheels

 

What is the hype with hubless wheels?  They certainly look cool. But what is the difference in how they function compared to spoked wheels?

There has been a popularity with innovative bicycles over the years made specifically with hubless wheels.  In fact, countless prototypes have been created and produced to show that this type of genius can work.

The way hubless wheels function is by placing a gear inside the rim of a wheel in which the wheel turns on the gear without a hub or chain.  The wheel is hubless and hollow giving it that “Tron” bike look.

In contrast to having a bicycle wheel with a hub and spokes, the hubless wheel can be lightweight and less to maintain.

The problem with hubless wheel can be in the cost as it is very expensive to create a gearbox and wheelset to offset the weight and force of a bike.  But this is not entirely impossible.

 

Bottom Line

 

When it comes down to wheel spokes, its function and purpose don’t have to be complicated.  

In reality, it is quite simply stated that wheel spokes are the tiny little strings that keeps a wheel strong and spinning.

There is two type of wheel spoke patterns that we discussed: radial and tangential, which each have their pros and cons.

If this at all peaked your interest in the science of spokes and their effect on wheel performance, please leave a comment.

 

Recent Posts

Share
Pin
Tweet
Share