Bike Parts Buying Guide

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Bike Parts Buying Guide

Any serious cyclist knows that the ability to find affordable parts for a bike is a key determining factor in any bicycle purchasing decision since, over time, bike components wear out and will need to be replaced.

The parts required are dictated by:

  • frame size
  • bike style
  • The kind of riding being undertaken.

Many cyclists may even be prepared to compromise on other aspects of their cycle if they know that they have a machine with components which can be easily and affordably purchased, for example on the online auction site eBay.

Here is a guide to some of the more common guides cyclists are likely to need at one time or another.  Knowing the various names and terminology will help when a buyer is shopping for new parts.

Bike Parts


This is the rod that attaches a wheel to a machine, and supports the bearings on which the wheel turns round.

Bar Ends

These allow for varying positions of the rider’s hands, and are the extensions fitting at the end of straight handlebars.


This lessens friction by helping rotation. Roller, sleeve and ball are the most common varieties most cyclists will need.

Bottom Brackets

These come in varying sizes and prices, and with different qualities. And, as with most cycle products, you will pay more for greater combinations of lightness and strength.

Essentially, a bottom bracket sits within the frame and is the axle which links both crank arms via the lower area of the frameset. It is made up of a set of bearings and an axle, so that pedalling is unimpeded. 

Perhaps unsurprisingly, one can expect to pay more for a bottom bracket that is lighter, has more strength, and leads to a smoother ride.


Clearly, few things are more important to a bike’s performance and safety than properly working brakes.

Road Bikes

In fact braking systems on road bikes have remained essentially unchanged for decades. Many use the caliper system, and these brakes are now lighter than ever and with greater stopping power.

Caliper Brakes:

These can be single or dual pivot. With the latter, both pads are pulled to the rum together, to give more power. Because these days only the rubber needs to be replaced, not the entire pad, so that replacing worn brakes could not be easier. In fact, modern versions of this braking system need very little maintenance.

Hybrid and Touring Bikes

Much will depend on what your individual bike is designed for. But, as a general rule of thumb, it makes sense to stick with kind of brake your bike came with, and replace accordingly, ideally by going to a reputable auction website like eBay.

Off Road Bikes

Historically, brakes on off-roaders have worked using cables, but, following the introduction of hydraulics, mountain bike brakes can now be run like the brakes in a car or on a motor bike.

The benefits of this include:

Cables are sealed and protected from the weather, and can therefore be changed less often.

Greater power and effectiveness with a more consistent braking response.

Disc Brakes:

Mountain bike disc brakes can run hydraulically or with cables, the latter being more affordable and generally better suited to novice riders. Equally riders can repair and maintain the system themselves while hydraulics need the intervention of a trained mechanic.

Riders need to suit the brake to the kind of riding they do. For example, cross-country disc brakes will be smaller and less heavy, with just one two pistons. (Performance depends on how many pistons a disc system has, and how big they are.) Pads need to be kept clean but it’s easy to replace them.

Rim Brakes

Of these, the most commonly found is the V-Brake, which combine power and affordability – especially when you buy them somewhere like eBay. These systems are low maintenance, and extremely light.

Long cantilever arms are linked by the cable passing through to provide a strong braking force to a rim. The only snag to these systems is that they can be tricky to replace, especially as far as the rims themselves are concerned. (The pads are rather easier.) And, the more braking force is applied, the more quickly the rims will wear down.

Hydraulic rim brakes were once in favour, especially by trial cyclists, but are now found less frequently.


Do not confuse brake and gear cables – they are not the same, mainly because of the way they fit at the end of the cable. Equally, mountain and road bike gear cables are not interchangeable.


Bike cassettes are the set of differently sized cogs that go on the back wheel axle. There are different strengths, sizes, weights and degrees of robustness, and they should be compatible with a bike’s drivetrain. A rider changing their cassette may also need to change their chain as well.

The size of a cassette needs to be compatible with how many gears the bicycle has.


Chainsets form part of the drivetrain and refers to the right and left cranks arms and the rings of the chain, which together make a single unit.

Here, the variety of different types available really is huge. Gearing will be massively affected if bigger or smaller chainring sizes are chosen. For example, if a rider finds the regular gearing on a road machine is too big for steeper ascents, gear ratios can be brought down with a more compact chainset.


This is also called the Derailleur Mechanism, and is often shortened to mech.

They are the component of the drive chain which moves the chain from one sprocket to another so the gear can be changed.

Rear Mechanisms

The rear mech controls changes in gear at the back of the machine, and stops the chain from slipping by giving it tension.

Rear mechs are different on road and off-road bikes – they tend to be heavier on the latter. The cages on road machines also tend to be shorter.

To buy the right rear mech consider:

  • The number of gear shifters
  • The number of sprockets the rear mech needs to move over
  • The number of teeth the biggest cassette sprocket has
  • The length of cage that is required

Front Mechanisms

Front mechs move the chain over the front chain rings, typically no more than three rings.

With many different varieties and sizes on offer, this can seem a somewhat complex purchasing decision. It will depend on:

The type of fitting required

The type of chainset being used

With mountain bikes, whether the mech swings from the bottom or top


On most bicycles, handlebars are built from aluminium alloy, or steel where greater robustness and strength are necessary. At the upper end of the market, carbon fibre is increasingly popular. And titanium bars can still be found, especially on eBay.

Riders need to balance having greater width, and therefore more control over the machine, and the need to turn quickly. For longer rides, and activities like cross-country racing, narrow, lower-slung handlebars are aerodynamically and ergonomically efficient.

For riders who feel confident trimming the handlebars themselves, they could consider buying a model that’s just a little wider than what they think they will require.

As a general rule of thumb, handlebars that are up to six inches wider than your shoulders provide the best balance between control, comfort and leverage, while inspiring confidence. Individuals may want handlebars that are wider or narrower than that.


Road Bikes

Wheels are an excellent starting point for any rider wishing to update their on-road machine. Upgrade to more aerodynamic, lighter ones and performance and speed can improve dramatically.

Here are some ways to narrow down the choices:

Decide on wheels that suit the tyres of the bike, whether that’s clincher or tubular.

As with so many cycling products, wheels need to be matched to budget, riding style and body weight. A daily commuter won’t need very lightweight, super speedy deep rimmed carbon wheels with small hubs and few spokes, nor would a rider who gives their bicycle quite a pounding.

Mountain Bikes

Again, there is lots of variety, especially on eBay, and new wheels can transform an otherwise sluggish performance of a bike. Going more lightweight will boost climbing and speeding up, which is important for racers.

Also, riders of a slimmer build may suit more slender wheels, but Sunday afternoon off-roaders who may be carrying a little extra weight, or who are not very technically experienced, may want to consider chunkier, more stable and hardwearing wheels.

Tubeless technology for mountain bikes has evolved, but rims must be compatible and tubeless valves present. Wheels also need to be compatible with the bike’s braking system.

Skewers and Rim Tape

Rim Tape lines the inside of the rim to help avoid punctures. Choose from lightweight plastic or the more commonly found cloth tape. If performance is especially important, go lightweight to boost acceleration.

Wheel Skewers fix a bike wheel into the frame’s dropouts, and are vital safety mechanisms. Make sure they don’t come loose while you are riding. There are many very lightweight ones on the market, and a number of different materials and finishes.

Buying Bike Parts on eBay

eBay is your one-stop shop for every bike part your bicycle will ever need, new and used, from every brand there is and in a range of styles and sizes.

And makes it easy to search for exactly what you require by choosing keywords in the search box to help you narrow down your search to shopping according to a number of different criteria including:

  • Brand
  • Condition
  • Size
  • Colour
  • Price

You can also ask the seller a question, so that you are making an informed decision before you commit.

And, thanks to eBay’s payment partner PayPal, shoppers can make their purchases in complete security and with peace of mind.


Riding the bike with parts which are worn out and need replacing can compromise performance and is unsafe.

Equally, for many cyclists, replacing parts on their machine is the way they make their machine their own, tailoring it to their riding style and needs, as well as their bike.

Traipsing out to the bike shops repeatedly for different parts can seem a chore, but that’s not an issue for eBay shoppers – everything they could possibly need is there, attractively priced and all under one virtual roof.

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