The 8 minute "youtube" movie below shows you how easy it is to convert a bike to single speed... enjoy... but do also read the techie stuff further down this page.

There are several methods of achieving a singlespeed bike.  Many of the strange components needed won’t be found in your local bike shop as demand for these items is pretty low. However you can buy almost everything you need from me.

We now sell a complete singlespeed start up kit: for around £47 you get a chain tensioner, a top KMC quality chain, some skinny chainring bolts, some Gusset hub spacers a 16 tooth cog and an 18 tooth cog. Use your existing chainring and go singlespeed. Click here to buy

BUY A BIKE… simply buy a singlespeed bike, or a frame with horizontal dropouts. These dropouts allow you to pull the rear wheel back in the frame to achieve chain tension. I strongly recommend the use of a device like the Surly Tuggnut (see picture) to ensure your rear axle does not slip in the dropout when you stomp on the pedals. The Surly device not only allows you to tune for perfect chain tension, it also opens beer.

CONVERT A REGULAR BIKE using a tensioner… Take off all the geared rubbish, and pop on a chain tensioner (see picture and shop). These are like tiny rear mechs that take up the chain slack. Some have a jocket wheel and hang down like a mech - others use a roller and push the chain up, these are better if you ride rocky and rooty trails where mechs get mashed.

You can also use the blooming clever White Industries Eccentric Eno Hub, the bolts that mount the hub to the dropouts are not in the centre of the hub, they are offset by around 7mm, simply rotate the hub to get tension, then lock down the allen bolts. I have used one of these for several years on an offroad cross bike and it has worked very well, both as a singlespeed and as fixed wheel bike. You can buy these from me for £125. We also have the Trickstuff eccentric bottom bracket, that fits regular frames at around £125... have a look at the movie below to see these two products.


You will also need to set up the rear wheel with one cog. You could buy a singlespeed specific rear wheel and use a screw on BMX style freewheel. An OK alternative is to take the geared cassette off the rear wheel and replace it with a single cog and some spacers. These can be purchased (see pic below), or you could use the spacers from between the cogs on a few old cassettes.  

When you strip down your chainset to one ring, you will no doubt find that the bolts that held two rings in place are too long to clamp down a single ring – but don’t panic, skinny bolts are available in the shop.

GETTING LUCKY: Everyone likes getting lucky... many beers have been consumed.. it's the end of the night and you're standards have never been lower and despite the stains, you're still attractive.... STOP, we're taking a different kind of lucky...

You may not need a chain tensioner, the distance between your drop outs and your bottom bracket may be spot on, and therefore allow you to run just a chain, a chainring and a rear cog… and get perfect tension.

You can help yourself to get lucky, by playing around with the size of your cog and ring. For every tooth you remove will reduce the effective bottom bracket to rear axle length by 1/8 of an inch. So you take up the slack by using a bigger cog or ring and create slack by using a smaller cog.

There is a brilliant and super rare component called a half link (see picture and shop). This is a single chain link that goes from wide to narrow within one link. Using this will make your chain half a link shorter or longer, equating to a 1/4 inch change in you effective bottom bracket to rear axle distance. Simply use a combination of these two techniques to get good chain tension.

IMPORTANT BIT: Chains stretch when used, so your chain will get slacker. You should check the tension regularly and adjust your ring/cog sizes, remove/add a half link, or replace the chain to maintain tension.



WHAT GEAR? Standard singlespeed offroad gearing is 32 teeth at the front and 16 at the rear, AKA 32:16. This gives you a 2:1 ratio. Any other 2:1 ratio will feel the same such as 36:18 or 42:21. However if you live somewhere particularly steep use a slightly easier gear such as 32:17 or 32:18. The table below is a gear inch table for 26" mountainbike rear wheels. Use this table to work out what gear will be harder or easier than another.
Front Chainring 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
Rear cog This table is for 26" wheels      
11 71 73 76 78 80 83 85 87 90 92 95 97 99 102 104 106 109 111 113 116
12 65 67 69 72 74 76 78 80 82 85 87 89 91 93 95 98 100 102 104 106
13 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98
14 56 58 59 61 63 65 67 69 71 72 74 76 78 80 82 84 85 87 89 91
15 52 54 55 57 59 61 62 64 66 68 69 71 73 75 76 78 80 81 83 85
16 49 50 52 54 55 57 59 60 62 63 65 67 68 70 72 73 75 76 78 80
17 46 47 49 50 52 54 55 57 58 60 61 63 64 66 67 69 70 72 73 75
18 43 45 46 48 49 51 52 53 55 56 58 59 61 62 64 65 66 68 69 71
19 41 42 44 45 47 48 49 51 52 53 55 56 57 59 60 62 63 64 66 67
20 39 40 42 43 44 46 47 48 49 51 52 53 55 56 57 59 60 61 62 64
21 37 38 40 41 42 43 45 46 47 48 50 51 52 53 54 56 57 58 59 61
22 35 37 38 39 40 41 43 44 45 46 47 48 50 51 52 53 54 56 57 58
23 34 35 36 37 38 40 41 42 43 44 45 46 47 49 50 51 52 53 54 55
24 33 34 35 36 37 38 39 40 41 42 43 44 46 47 48 49 50 51 52 53
On the road any big gear goes – I found 48:16 hard work, and 42:16 about right. You will find a selection of singlespeed cogs and chainrings in our shop - Email me if you cant find the size you need.

BIG TEETH: Just like Janet Street-Porter, jolly big teeth are a recipe for success. Both your front chainring and rear cog should have full size tall teeth. Many geary teeth are cut down to allow easier shifting of gears – you want your chain to stay on, not jump off (nasty violent and maiming injuries may follow).

When buying chainrings you need to know the BCD aka  Bolt Circle Diameter. This is the measurement of an imaginary circle on the chainring hitting all the bolt holes. The best way to calculate this is by measuring the exact distance (center to center) between 2 neighbouring bolt holes. Then find that number on the correct chart below to determine the BCD for your chainring and cranks...

BCD chart for 5-bolt chainrings
Bolt to Bolt (measure center to center) BCD Bolt Circle Diameter 
32.9mm 56mm
34.3mm 58mm
43.5mm 74mm
55.4mm 94mm
64.7mm 110mm
76.4mm 130mm
79.5mm 135mm
84.6mm 144mm
BCD chart for 4-bolt chainring
Bolt to Bolt (measure center to center) BCD Bolt Circle Diameter 
41mm 58mm
45.3mm 64mm
48.1mm 68mm
73.6mm 104mm
79.2mm 112mm


CHAIN TENSION: The secret to a good reliable single speed is good chain

tension. A slack chain will cause you chain to skip off, often with hideous consequences (I have scars). A Surly Tuggnut or Spot Rocket tensioner prevents this by allowing you to fine tune the tension (it also allows you open bottles of beer)


CHAINLINE: When setting your bike up you should try to get the chainline as straight as possible. The chainline is the route your chain takes from the cog to the chainring. Get down on your knees and squint up close at the chain - looking along the bike. You want to get it as straight as possible by either moving your rear cog about (by playing around with the spacers if you are using an adapted hub), moving the front ring to the other side of your crank, or using a bottom bracket that's narrower or wider. Trial and error, you may get lucky first time.

VERY IMPORTANT BIT: All bloody hell will break loose when your chain skips off the ring. This always happens when you are mid sprint. All the resistance that you are pushing against with your entire body will suddenly disappear. You will throw your face at the ground, your bike over your shoulder, and your gentleman’s regions will always head straight for something sharp and metallic. Use tall teeth, check the chain tension, make sure everything is clamped down tight and wont slip, and you will live a long and frisky life.

DONT FORGET ITS FUN: Beyond the above I would also say you should always wear a lid, have fun, do big (environmentally sound) skids, don’t take any crap from motorists, and stop at a pub towards the end of your ride to replace lost carbohydrates.

In the movie below I talk you through the techie stuff...


CHAINS:  I reckon 3/32” width chains are the best option. Many people assume that 1/8” are stronger, which can be true… you see 1/8 chains tend to BMX chains and built tough. And 3/32 tend to be XC chains and less burly. However we sell KMC pro race chains in 3/32 and 1/8, they are both damned strong dedicated one speed chains. They are the exact same chain except one is wider.

So 3/32 is just as strong, and lighter too. You will also find that getting 1/8 cogs and rings is difficult, you will have much easier time if you stick to 3/32.

1/8 rings and cogs are wider and will last long than a 3/32. But again we have this covered. We sell the super burly Surly stainless chainrings that wear incredibly well, negating the need for 1/8 rings and cogs. You can run 1/8 chain on narrower cogs or rings, but you cant run a 3/32 on a wider cog or ring.

You should always ensure your chain is a good condition. Get a fresh chain whenever you replace cogs or chaings. Snapped chains lead to horrible crashes.