A Singlespeed bicycle, is a type of bicycle with a single gear ratio. The one-speed revolution actually involves two different styles of bikes, singlespeeds and fixed gears, also known as a fixie. These are not the same thing, although they have much in common. As long as the back wheel on a fixed gear bicycle is in motion the pedals are also in motion. This gives the rider increased mobility, but can also make riding fixed gear in hilly areas quite a chore.

Another aspect of single speed bicycle that separates them from geared bikes is their simplicity and light weight. Because lack the ability to change gears they require substantially fewer parts than typical geared bikes.

Modern 24-27 speed bikes are marvels of technology, and allow a cyclist to select the gear ratio that will make the most efficient use of his/her energy. If what you're after is getting the maximum possible speed/distance for the minimum effort (and there's nothing wrong with that!) you need a multi-speed bike...but, efficiency isn't everything.
If you're riding for sheer pleasure, or for exercise, you don't necessarily place that high a premium on output results, as measured in speed, distance or vertical climb. Instead, you may care more about the actual experience of riding your bike. In this case, you may be a candidate for a singlespeed bike.

Riding a singlespeed can help bring back the unfettered joy you experienced riding your bike as a child. You don't realize how much mental energy you devote to shifting until you relinquish your derailers, and discover that a whole corner of your brain that was formerly wondering when to shift is now free to enjoy your surroundings and sensations. A singlespeed bike dispenses with the weight of the derailers, shifters, cables, extra sprockets. They are also considerably more sturdy and reliable than multispeed bikes.

Quality Singlespeed can be expensive. For this reason it's not uncommon for people to convert their old road bikes. Conversions like these are a lot of work, but are a much cheaper alternative to buying new, and can be very fun and rewarding.

For this guide I'll be explaining the full process of converting a road bike. This includes disassembling frame, doing a full paint job, and lastly reassembling it with the necessary parts. For a lot of the build we'll be recycling old parts from your original bicycle. In addition most of the tools we'll be using are fairly standard and you probably have already, but some tools are bicycle specific and need to be bought separately. If all goes well, we'll be left with a practically new Singlespeed for half the price of buying one, and we'll have learned a lot of things along the way.

Step 1: Choosing a Bike

If you are looking for an inexpensive way to get into singlespeed riding, you may want to consider starting with an
older road bike. If you are not sure what to look for, there are many articles online.

The most important part of any bicycle is the frame. For a Singlespeed, most any road bike frame will do, but there are a few things to consider.

First of all, when choosing a frame for your new bike avoid frames with vertical dropouts if you don´t want to have a chain tensioner. The dropout on a frame is the slot that the rear wheel slides into. Because of how the chain tension on a Singlespeed bike works, only frames with horizontal or semi-horizontal dropouts are acceptable.

Second, it's very important that you pick a frame size that is right for your body type. A good frame should be short enough to easily get on and off, but tall enough so that you don't have to stretch your legs to pedal. If you're still having trouble figuring out what size is right for you here is a calculator that will help.

If the bike has the older 27 " wheels, you don't have to replace the 27 " wheels because Tires , and rims , are still available for this size.

But where do you find a bike to convert ? For this guide I'll be restoring an old road bike I found after purges of the private housing cooperative's bicycle storage. You should try visiting garage sales or browsing craigslist in search of a project bike. You might also consider converting a road bike you already own.

Step 2: Disassembly

Here are the tools you'll be needing for taking apart your bike

Tools

Vice grip
Allen keys
Flathead screwdriver
chain separating tool
Lockring tool
Needlenose pliers
Socket wrench (and heads in different sizes)
Adjustable spanner (medium, large)
Crank arm tool
(chain whip)

Using the tools above remove everything carefully and save everything. It might also be a good idea to put nuts and bolts from different parts of the bike into labeled bags. This is because we'll be reusing a lot of these old parts, so be careful not to lose anything.

Components to Remove

Shifters and Cables
Both Derailers (can be used as a chain tensioner if needed)
Chain (if it's old and worn)
Chainring (I'm using two chainrings and a chain tensioner to get two gear options)

If your old bike has not had any work done on it recently, then you should also check and replace as needed:

Front and rear brake pads
Front and rear brake cables
Tires and tubes
Headset bearings
Bottom bracket bearings
Wheel hub bearings.

Now that you've removed everything from your bike take a minute and asses the quality of your frame before moving onto the next step.

As you can see the paint on this frame is a little bit worn and frankly I'm not too fond of the color. Because of this I have no problem with repainting it. However, if you're converting a newer bike into a road bike you might find that the paint on your frame is hardly worn at all. In that case, unless you absolutely despise the color I would recommend against repainting the frame. Painting a bike is sometimes a long and hard process, the paint you apply will not be as durable as the paint that is already on your frame. This is because professionally painted bikes are painted using a process called powder coating which practically fuses the paint with the metal of the frame. If you do decide to repaint your bike move on to the next step of this guide, if not go ahead.

Step 3: Painting

The process of painting your frame is by far the most difficult part of this project. However it's also the most rewarding and it allows you to personalize your bike to your heart's content.

Before we can apply any paint to our frame we must first remove the paint currently on it. This is important to allow for future paint to stick to the frame.

I choosed to remove the paint by hand with sandpaper and power sander. You can also use paint remover paste or spray.

Once you're satisfied with the amount of paint removed from the frame, wipe any residual dust or oil from the frame away with a wet paper towel. It's crucial that the frame is as clean as possible for when you paint it.

Next tape up any chrome or decals with painter's tape and fill in any holes in the frame with newspaper. You do not want any paint to get inside the frame.

Now you're ready to paint. For the best quality paint job possible with typical spray-paint we'll need to use a primer and a clearcoat in addition to our solid color.

For my bike I decided to go with a classic white color. It's best if the color of your primer matches that of your top coat.You'll want to wait for a warm dry day when painting. If you try and paint in the cold or when it's very humid out your paint will run and you'll end up with a horrible paint job. Find somewhere to hang your frame up so that you can paint all surfaces without having to touch it.

First apply a thin coat of primer using quick straight motions to ensure that the paint doesn't build up and drip. Once you have fully coated the frame repeat the process a second and third time. You'll want at least three coats of primer before you can apply the top coat. Once your primer dries take the frame down and lightly sand the surface. This creates a rough surface so that the next coat has no problem sticking. Next, apply two or three layers of your top coat being just as careful to prevent the paint from running. Lastly, after the paint has fully dried apply a few layers of clear coat. This gives the paint additional strength as well as a nice shine.

Finally remove all of the tape and newspaper to reveal your stunning new paint job !

Step 4: Assembly

Now that we've painted our frame it's time to reassemble our bike. In order to make a functioning singlespeed bicycle we'll be using mostly parts that we already have from our original bike.

New parts (optional)

Tubes
Tires
Breaks
Break lever
Handlebar
pedals

Once you have all of your parts its time to put everything onto your frame. If you have any, it's a good idea to grease any threads before screwing in bolts to make removing them in the future easier. Frankly the order you add everything to the bike doesn't mater, but I like to start by reattaching the bottom bracket.

Depending on your bike project you may need to do some conversions.

Conversion Work

New vs. Old Wheel Decision
(First you have to decide if you want to use your old wheel or buy a new fixed-specific one)
Freehub Rear Wheels
(Not for fixed gear, only for singlespeed).
Setting chainline
(A procedure to ensure it is staight)
Respacing to get this chainline
(To get the sprocket in the correct position for a straight chainline)
Redishing
(To move the rim into correct alignment with the frame)
Sprocket/Chainring Selection
(Thoughts on deciding what gear ratio you want)
New Chain Length(A procedure to select the best length of chain)

The Chainline should run straight from the chainring to the sprocket. A couple millimeters either way will make a difference. If you hear the drivetrain making noises, it's probable that the chain's side plates are hitting the sprocket or chainring teeth. You will have to get the chainline closer to perfect. Since both the rear sprocket and the front chainring can be positioned in or out ( from the centerline of the bike ) with spacers, you have two variables with which to work.

Remove links of the chain until it is the proper length and then add it to your bike.

I'm using the rear derailleuras as chain tensioner. I haven't decided which gear ratio that is best for me. So I decided to have both the two front chainrings until I'm sure.

Slide the rear wheel back along the dropout until the chain is sufficiently taught and tighten the rear wheel bolts. Also make sure that the rear wheel is correctly aligned with the frame. This is why a horizontal dropout was necessary.