The crank, or chainset, of a bicycle is made up of a number of different parts, and these parts combined are what give the bike forward motion when the pedals are pushed. There are five main parts found in every crank that are extremely important, and it's very helpful for buyers to understand what exactly these parts do. It's also helpful to know about the various metals and materials used in crank part manufacturing, and how these materials can influence the quality of a cycle.
If buyers are searching for replacement crank parts for their bicycle then they should look for these parts on eBay. The site has a larger selection of new and used bicycle parts than any store or dealer, and the parts are generally sold at quite low prices. This guide shall examine the top five crank parts found in every bicycle, and explain how to find these parts on eBay.
The Top 5 Crank Parts
It's hard to determine which crank part is the most important, so instead this list will present the five most important crank parts, but without any sort of placing order. Instead, these are the five important parts starting with the crank arm and moving inwards.
1. The Crank Arm
The crank arm is the component that connects the pedals to the main crank unit. It is the crank arm that is responsible for the transference of power between the pedal and the sprockets. The crank arm is attached to the pedal via a small spindle that is usually screwed tight, but the pedal is free to rotate around this spindle. This is important as if the pedal were fixed it would be quite uncomfortable to use.
The crank arm is attached to the sprockets by the crank bolt. This is a large bolt and nut that keeps the two parts together and moving in unison. The crank bolt needs to be tight, but not too tight as this can strain the arm or the sprocket leading to cracks. It's a good idea to buy a dust cap for the crank bolt, as this will cover the bolt and prevent water or dirt from getting in at it.
Crank arms can be made from a number of materials, but the most common is an alloy of aluminium and steel. This ensures that the crank arm is strong enough to take a knock without buckling, but keeps it relatively light. The aluminium also makes the crank arm rust resistant, and this is important because the arm is constantly in motion when in use, and rust will make it loose and unstable. Road and racing bicycles used for competitive cycling tend to have crank arms made from carbon fibre, but parts manufactured from this material can be quite expensive. It's important for buyers to choose a crank arm that is the correct length for them, and to find out what this is, as all they have to do is complete the following simple equation.
(1.25 x Inside Leg in cm) + 65 = Recommended Crank Arm Length in millimetre.
2. The Sprockets
The sprockets, also known as known as the chainrings and the chainwheels, are the small circular wheels that are connected to the crank arm. The sprockets have a number of teeth or cogs, and these teeth are what keep the bicycle chain in place.
As the cyclist pushes the crank arm in a circular motion, the sprockets turn in unison, and as a result turn the chain and the rear wheel. The sprockets are also known as the front derailleur, and the amount of sprockets a bicycle has is a reflection of how many shifter speeds the bicycle is capable of. To work this out simply multiply the number of sprockets on the rear derailleur by those on the front derailleur.
So if a bike is described as eight-speed, then this means there are four sprockets on the rear, and two on the front. The majority of sprockets are made from steel, as this crank part needs to be able to withstand a fair amount of wear and tear. However, aluminium sprockets can be bought, and although not as strong, these are much lighter and are very suitable for use on road and racing bicycles.
3. The Crank Spider
The spider is the piece that keeps everything in place, safe and secure. Not all bikes have crank spiders, and some have very simple designs. However, even the simplest designed crank spider can be beneficial, and it's advisable for buyers to add one to their cycling set up if they do not already have one. The spiders are placed next to the main crank body, and keep everything in place with a series on bolts and nuts. Most of the spiders found on mass produced bicycles are made from some form of metal, but if looking for a replacement spider then try buy one made from carbon fibre. This material is very strong and will provide excellent protection for the main crank housing, while stopping rust from spreading from part to part. Carbon fibre is also extremely light, so it is suitable for use with both mountain and racing bicycles.
4. The Chain Guard
Similar to the crank spider, this crank part is made to protect not only the main crank body but also the area where the chain feeds onto the sprockets. Bicycles don't tend to come with chain guards, but it's a good idea to purchase one, especially if the bike is used for off-road cycling. The guard will stop dirt, mud, loose debris and rain from getting in at the crank housing. Chain guards can be made from various metals, but it's a good idea to buy one that has been manufactured from a hard and durable plastic. This reduces the risk of the guard splintering into sharp pieces if it is hit with a strong impact.
These are not found on every bike, but can be very beneficial to people who engage in freeride and downhill mountain biking. The chainguide consists of a metal or plastic cover placed around the edge of the sprocket that touches the chain. This stops the chain from jumping off or slipping when the cyclist is moving over rough terrain. Buyers looking to buy a chainguide should first measure their sprocket, and use these dimensions to find an apt guide.
Searching for Crank Parts on eBay
To search for anyone of the above crank parts, take the following steps.
* The first thing to do is log on to eBay. When the page has loaded up click on the Shop By Category drop down menu at the top of the page. The menu should open up, and buyers should be able to see a link titled Cycling, which is found underneath the Sporting Goods heading. Click on this link.
* On the following listings page, click on the Bicycle Components & Parts link, which is near the top of the Categories table on the left hand side of the page.
* Buyers will now see a number of different links that list to various crank parts including Cassettes, Freewheels & Cogs, Chain Guards & Bash Guards and Chainrings & BMX Sprockets. Buyers should click on the link relevant to the part they are searching for. If instead, the buyers want to see a list of every crank part for sale on eBay then they should remain on the Bike Components & Parts page and type Crank Parts into the search bar and press enter.
* The more information entered into the search about a specific crank part, the easier it will be to find. Buyers should enter the name of the manufacturer, the composite material, the size and the type of gearing mechanism the crank part is suitable for.
* Buyers can change the amount of listings shown on a page by scrolling to the bottom of the page and clicking on the desired amount. Crank parts are listed in groups of 25, 50, 100 and 200.
* Buyers should check the description box on the item page for further details about the part e.g. exact measurements or current condition.
* If buying a used crank part then remember to study any photos provided of the part for physical defects or damages. More photographs and additional information can be requested by using the Ask A Question feature, which is located below the description box.
* Review the seller's history before placing any bids, and avoid sellers with high percentages of negative feedback.
The five most searched for crank parts found on bicycles today are the sprockets, the crank arm, the crank spider, the chain guard and the chain guide. It's important for buyers to understand what each of these parts do before they begin a search for a suitable replacement part. It's also important for the buyer to be aware of the various metals and materials used in the manufacturing of these parts, as this will influence the quality and durability of the part.
Any buyers looking for replacement crank parts should head to eBay as the site has a large selection for sale at very reasonable prices. Buyers that spend some time reading through the listings are sure to find a suitable replacement crank part.