The following is a fairly comprehensive guide in how to remove the gears on your bike and change them to a single speed. This guide will talk about removal of the cassette. Adding your single gear, chain tensioner and chain as well as removal of the chainset and adding a single chainring. As a difficulty rating I would give this a 4 out of 5. The rating is high more because there is lots of things to cover here but each individual step isn't that difficult to do.
You will need Specialist bike tools for this job and there may be variations depending on your drivetrain. To start you will need to buy the conversion kit. I've used a 32t front here on a 16t rear, having a 2:1 ratio which is good place to start.
Parts include:
16t Cog with various spacers
Chain tensioner
Singlespeed Chain
32t 104bcd Chainring (optional)
Chainring bolts (short)
Tools Required:
Allen key Multi Tool
Cassette Removal Tool
Chain Whip
Chain Splitter
Crankset removal Tool For either Hollow tech or splined cranks
Workstand (Optional but it helps!)
Grease
Get your bike set up in your workstand or somewhere that supports your bike in a solid position.
Rear Wheel
Remove the rear wheel from the frame. The tools you'll need for this job are the Cassette Tool, An Adjustable Spanner if you don't have an all in one cassette tool, and Chain Whip.
Using picture above as guide put you cassette tool into the lock ring. I reattach the quick release over the tool to stop it slipping off when twisting. Using the chain whip to hold the cassette in place turn the tool anti-clockwise to remove. the Cassette should just slide off from the wheel leaving the bare cassette body. Sometimes the cassette may not slide off easily in which case use a small rubber mallet to tap it loose.
Clean the cassette body removing any grime or grease. Next, it's time to get your spacers cog and lock ring. These slide easily onto the cassette body but now comes the hardest part of the exercise, knowing what spacers to place in which order. It is a bit of case of trial and error. Your aim will be to have a nice straight chain line from your back wheel to the chainset meaning less rub on the gears and a smoother ride. More likely the cog will need to be closer to the outside of the cassette body.
With all the parts put on, screw back on the lockring holding the parts in place. Use just the cassette tool to tighten it up (no need for chain whip).
Your finished wheel should look like the picture above. Remember you may have to repeat this process a few times to get the chain line right in later stages.
Rear Derailleur
Using your Allen keys undo the bolt to remove the cable to the rear derailleur as shown by the left hand arrow. The right hand arrow shows the bolt that will be need un-screwing to remove the rear derailleur from the frame.
At this point the chain will need removing. If you have a Sram chain the you can unlink the chain by pushing the chain together where the gold power link is. If not then you will require a chain tool. Push the pin nearly all the way out (leaving a little in case you want to reattach) with the tool to split it. Remove the chain from the derailleur and Chainset.
Once the derailleur and the chain have been removed it's time to attach the Chain Tensioner. This is put in the same place as where the rear derailleur was bolted in. Lightly grease the threads before attaching
When attaching the Tensioner pay attention to the small pin at the back. In the picture above (taken from behind the frame hanger) you can see the pin sits up against the frame hanger. If it is put on the wrong side, the tensioner will slip and not work.
With the Tensioner attached to the frame the wheel can be put back into the frame. So far so good! At this point it is a good time to remove all the gear cables from the bike including the inner and outer cables from the front and rear derailleur.
Chainset
Starting with the Front Derailleur. Unscrewing the Allen key bolt will allow the derailleur to be easily removed from the frame. You are now ready to remove the chainset.
Using an Allen key loosen off the bolts to the Non Drive side Crank arm and remove the plastic cap with the specialist tool as shown. There are some variations to this so it may be worth checking out what is required to remove your chainset. This particular removal method is for Shimano components.
Once the Non driveside crank is removed the rest of the Chainset can be removed from the frame. It should pull out easily but if not a gentle tap from a rubber mallet should move it. Clean out the bottom bracket from any grime ensuring that inside is clean and dry.
Using an Allen key to remove the outer chainring and inner chainring. The bolts can be tight so a long Allen key may be required. Once removed, reattach the middle chainring (or new singlespeed chain ring) using shorter Allen key bolts grease each bolt before tightening. Ensure that the chainring sits where the outer chainring used to be, on the outside of the cranks spider arm.
With the chain ring in place, replace the cranks onto the frame. When attaching the plastic cap only screw it hand tight to nip up the crank arms and then tighten the Allen key bolts. Hopefully you will end up with something that looks like the picture above.
Putting It All Together
Next you will need to put on your new single speed chain. Before you start it's advisable to force the tensioner toward the chain stay by holding it in place with a cable tie or cord. This will just make it easy to put the chain together as you won't be fighting against the tension on the chain.
Feed the chain over the cog through the bottom loop on the chain tensioner and around the chainset. Bring the chain together. At this point you will notice that you have an excessive amount of chain left. Use the chain tool to break it down to length. The chain can then be attached using the connecting plates supplied with the chain. Remove the cable tie on the Tensioner and you are finished! Or are you? Now you need to check that the chain is tight. There shouldn't be much play in the chain or it'll fall off on your next bumpy decent. If its loose, try taking some more links out of the chain.
Rotate the cranks to ensure that the chain runs smoothly with out coming off or rubbing. You may need to adjust the jockey wheel on the tensioner so it sits in line with cog above it.
No its time to check that chain line. Is it straight? Does it follow a parallel line with bike? As you can see from the two pictures above some adjustment had to be made with the spacers. The top picture; the chainline may look straight but the chain line from the wheel moves away from the frame to the chainset. This is corrected in the next picture giving a much better and smoother chainline.
With the chainline corrected then its time for a little test ride. Hopefully everything will run fine and now you can go off and enjoy another great way to ride your bike.
