Introduction Welcome to this guide I have put together by looking up information by professionals, such as Sheldon Brown, Bike Radar and more. There will be the introduction and information, then how to convert below. I have made this for road bikes, and thought it would be good to summarise the guide into one whole post. This is how I learned to do mine. NOTE to Newbies; Singlespeed is coasting, whereas fixed gear is where you have to continuously pedal, but the guide applies to both types as it's only a different type of hub as you will read. Post your results if you wish to. What is Single Speed? (Following information credited to Sheldon Brown) While any bike that doesn't have multiple gears is technically a "single-speed" bike, current use of the joined word "singlespeed" generally refers to a bike with a one-speed freewheel and hand brakes, distinct from both one-speed cruisers (these have coaster brakes, not freewheels) and fixed-gear machines. Why ride a Singlespeed? 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!) a multi-speed bike is what you need...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. Paradoxically, a singlespeed is, in another sense more efficient than a multispeed bike! While the single gear ratio will not be the "perfect" gear ratio for all conditions, in the conditions which fit the single gear, it is considerably more efficient mechanically than the drivetrain of a derailer bike. A singlespeed bike dispenses with the weight of the derailers, shifters, cables, extra sprockets and longer chain. In addition, a singlespeed gear train runs the chain in a perfectly straight line from sprocket to chainwheel, and avoids the serpentine wind through the pulleys of a derailer. You can really feel the difference! A singlespeed is noticeably quicker and easier to pedal than a multispeed bike in the same gain ratio Singlespeed bikes are also considerably more sturdy and reliable than multispeed bikes. There's no derailer to bash if the bike falls over, catch on the underbrush or to get overshifted into the spokes. The rear wheel itself is a lot stronger than one made with off-center (dished) spoking to make room for a whole bunch of sprockets on one side. Singlespeed vs Fixed Gear Singlespeed vs Fixed Gear The one-speed revolution actually involves two different styles of bikes, singlespeeds and fixed gears. These are not the same thing, although they have much in common. A fixed gear bike differs in that it does not permit coasting; when the bike is rolling, the pedals will turn, just as with a child's tricycle. To enjoy the one-speed experience to the max, a fixed gear is the best choice if you ride mostly on pavement. A fixed gear gives a degree of control and one-ness with the bike that is not equaled by a freewheeling bike. This site also contains several articles dealing with Fixed Gear Bikes. Fixed gear is not ideal for all circumstances, however. A fixed gear is not well suited for seriously hilly terrain, and, more importantly, is not good for technical mountain biking. A mountain biker in difficult terrain must be able to control when each pedal is down, to avoid striking a pedal on rocks, logs or other obstructions. Similarly, jumping over obstacles is much more difficult on a fixed gear. If your single gear is low enough for off-road climbing, it will be too low to spin on the descents. You don't have to choose once and for all between fixed and freewheel, because the same bike can be both, if you use a reversible "flip-flop" hub. Many cyclists interested in simplifying consider going to a singlespeed freewheel as a way to "test the waters" with the idea that if they turn out to like that, they might later convert to fixed gear. This is generally the wrong way to approach it, in my opinion. I STRONGLY recommend starting out with fixed gear. If it turns out to be a problem, you can easily convert to freewheel later if you want to...but my bet is you won't want to if you give fixed gear a good try (typically takes a couple of weeks of regular riding to get past the strangeness, but then it's quite addictive!) Most folks who set up their bikes with a fixed/free flip-flop wind up using the fixed gear side pretty much all of the time. The freewheel option is mainly useful for when you have taken a longer-than-usual ride, and need to get home even though you're all tuckered out. Freewheel vs Coaster Brake While coaster (backpedaling) brake bikes are also, mostly, single-speed machines, I don't recommend them for technical off-road use. Coaster brake hubs have a good deal of internal friction, and coaster brakes have a number of serious drawbacks: You can only apply the brake forcefully in two crank positions. If your foot slips off the pedal, you can't brake at all. If your chain breaks or falls off, the brake fails. If you don't have a hand-operated front brake, you can't stop as short as a bike that does have one. On a long descent, a coaster brake will overheat and burn the grease inside it. It is very awkward to get started, because you can't rotate your cranks to a good starting position without lifting the rear wheel. Because you usually switch feet before restarting, it is impractical to use toe clips and straps, or clipless pedals. Wheel removal/replacement is more complicated, due to the need to attach the brake arm to the frame, and because you can't get a coaster brake with a quick release. You can't have a flip-flop hub. Coaster brakes are OK for beach cruisers, and flatland applications in general, but not a good choice for sporty bikes, nor for rolling or hilly terrain. Short-reach caliper brakes and modern MTB cantilevers, either traditional center-pull or newer direct-pull styles, can lock up either wheel at will, but also permit fine control over the modulation of each wheel's brake. Hubs for Singlespeed Bicycles There are four ways you can go, as far as hubs are concerned. You can use a flip-flop hub, a multi-speed freewheel hub, a cassette hub, a single-speed BMX hub, or a singlespeed MTB hub. Flip-flop Hubs Flip-flop, or double-sided, hubs are threaded on both sides. Usually one side has a track-type threading, (with lockring) and the other side is threaded for a single-speed standard freewheel. The usual way to use a flip-flop hub is to have a fixed gear on one side, and a single-speed freewheel on the other. The freewheel sprocket is larger than the fixed sprocket, providing a lower gear. On an MTB, you use the fixed-gear side for most pavement riding, and save the freewheel for off-road use, or for getting you home when you are tired. Having the freewheel larger than the fixed sprocket gives you a lower gear when you are using the freewheel. This makes it easier to climb. Since you can coast when you are using the freewheel, the lower gear is no disadvantage on the descents. Single-speed freewheels are commonly used on BMX bicycles: most shops that deal in BMX parts should stock them. The common size used for BMX is 16 tooth, but 17, 18, 20 and 22 tooth freewheels are available. Note, there are two types of hubs called "flip-flop": Fixed/free, this is the type I speak of above, with a "track" side and a freewheel side. BMX type...BMX flip-flop hubs have two different freewheel threads, a standard one on one side, and a special smaller-diameter freewheel thread on the other, designed to work with special small freewheels (14, 15 teeth.) These are now quite rare, but if you are calling around looking for "flip-flop" hubs, make sure you get the right kind. Conventional Freewheel-type Hubs The cheapest way to convert a multi-speed bicycle into a singlespeed is to use the original rear hub, assuming that it is made for a conventional threaded freewheel. A single BMX freewheel will thread right on. Unfortunately, the chainline is likely to only work with your granny gear unless you re-space the rear axle and re-dish the wheel. Cassette Hubs It is easy to convert a Shimano cassette Freehub ® for singlespeed use. The simplest way is just to remove the derailers, shorten the chain and thread it onto the chainwheel and rear sprocket of your choice. This is less than ideal, however, because you've got the extra weight of the unused sprockets to deal with, and the chainline will probably be crooked. The sprockets used on multi-speed cassettes are designed for easy shifting, which is not a good thing on a bike that isn't supposed to shift! The better way to convert a cassette Freehub ® is to remove the 7-, 8- or 9-speed cassette and replace it with a single sprocket. You will also need a bunch of spacer washers to hold the single sprocket in place. You can often get a suitable number of spacers by taking apart a couple of discarded, worn-out cassettes. Having a single sprocket sandwiched in a stack of spacers makes it easy to get the sprocket properly aligned for perfect chainline with whichever chainwheel you choose to use in front. You can use one of the old sprockets from your taken-apart cassette, but it you are less likely to have accidental derailment if you use sprockets made for single-gear use. The best choice for this is to use BMX cassette sprockets. These sprockets are quite inexpensive, and are available in a range of sizes. They have taller teeth than sprockets designed for derailer use. Disc Brakes Disc brakes are increasingly popular for off-road use. They don't depend on good rim true, and don't get contaminated by mud. A number of high-end ready-made singlespeed bikes are supplied with front and rear disc brakes. In my opinion, this is not a good thing. Personally I consider a rear disc brake a very poor choice for a singlespeed. It would preclude you from using a flip-flop hub. Also, as the chain wears and the axle is moved backward to take up the slack, the relationship of the disc to the caliper will change. That can't be good. Singlespeeds are generally not practical for terrain so steep as to require dual disc brakes. There's no such problem with a front disc brake,but I strongly advise against getting a rear disc setup for a singlespeed. (There are different problems -- be aware of them. See information in the article on skewers and in Jobst Brandt's article about brakes.) Solid-Axle vs Quick Release Conventional wisdom is that you need a solid (nutted or "bolt-on") axle hub for fixed-gear or singlespeed use, and that a quick-release will not hold the wheel solidly enough in a horizontal forkend. This is not true, however. Since most newer bikes have vertical dropouts, people have gotten used to wimpy aluminum skewers, and often don't adjust them as tightly as they might. If you use a good quality (Shimano is the best) skewer, tightened securely, it will hold just fine in any type of dropout or forkend. A quick release is a considerable timesaver in switching a flip-flop wheel around, and having a QR means that you don't need to carry a big wrench to be able to replace a damaged inner tube. Frames for Singlespeed Conversion - Vertical Dropouts Most newer bikes (made since the late-1980's) have "vertical" rear dropouts, where the wheel slides upward as you install it. These are a problem when you want to dispense with a derailer, because you need some way to regulate chain tension. Most newer frames made for derailer use have vertical dropouts. This is convenient when you're actually using a derailer, but causes a complication when you wish to simplify your drive train, either to singlespeed, fixed-gear or an internal-geared hub. The simplest way around this is to install a chain-tensioning pulley of some sort. This is not an option for fixed gears or coaster brakes, but is the easiest solution for freewheeling bikes. Even for singlespeeds, though, it is nicer to be able to do without a klugy and inelegant chain tensioner. Fortunately, most "vertical" dropouts are not exactly vertical: they usually have a bit of a slant. As a result, it is sometimes possible to use this type of frame. To make it work, you may have to play games with chainwheel sizes. One of my fixed-gear bicycles is based on a Cannondale touring frame. It happens that there is just enough adjustment to make it work with my preferred 42/15 combination. If the chainstays were a bit different in length, I could replace the 42 with a 41 or 43. Adding or subtracting a link in the chain will move the axle 1/2". Changing either sprocket size by one tooth is the equivalent of moving the axle 1/8" (4 mm). Thus, if I wanted a 5.75 gain ratio (75" / 6 meter gear), I might first try a 42/15, this gives a gain ratio of 5.77 (75.6" / 6.05 m gear). If the chain was too loose, I could take up 1/8" (4 mm) of axle movement by replacing the 42 with a 43. This 43/15 combination would raise my gain ratio to 5.91 (77.4" / 6.19 m). Alternately, I could get the same axle position with a 42/16 --5.41 (70.9" / 5.67 m). If I was not happy with these choices, I could add a link to the chain and switch to a 45/17 --5.45 (71.5" / 5.72 m) If I added two links to the chain, I could get the same axle position with a 48/18 --5.49 (72.0" / 5.76 m) Another possibility would be to do a little bit of filing at the back of the dropout to let the axle move back just a bit. It is also possible to grind or file a flat on each end of the axle to allow a bit more adjustment, like this: I have been experimenting with a more drastic solution: on my Bianchi Osprey, I have cut the rear axle short so that it doesn't protrude past the surfaces of the locknuts. Thus, only the quick-release skewer goes through the dropouts. Since the skewer is quite a bit thinner than the actual axle, this gives me considerably more adjustment room. If the skewer is properly tightened, the axle is held in place by the friction of the locknuts being pressed against the inside of the dropouts. If this were not the case, horizontal dropouts would not be usable, since the forward pull on the chain creates a larger force against the axle than supporting the rider's weight does. Just to be on the safe side, I am carrying a spare skewer along with my spare tube. Eric House has prepared a whole web site devoted to the problem of finding sprocket combinations that will work with vertical dropouts. He has developed charts and Java applets that show the options available for particular chainstay lengths. Check him out at: fixin/. He is also supplying hubs with special eccentric axles to facilitate fine tuning chain tension. It can be difficult or impossible to use a frame with vertical dropouts with a flip-flop hub. Hub/Frame Spacing Most mountain bikes have 135 mm spacing between the rear dropouts; most newer road bikes, 130 mm. Fixed-gear hubs are commonly available in these spacings, although they are more commonly found in the narrower, 110-120 mm spacing which is standard for track hubs. If you are using a newer frame, with wider spacing, you may want to replace the axle. You may want to replace the axle in any case, because singlespeed hubs generally come only with solid axles, not quick release. Drivetrain - Chainline Derailer bikes can work fairly well even with the chain running at a considerable angle, but this should not be done with a singlespeed setup. It is quite important to get the chainline just right. I usually check the chainline by installing the hub in the bike, with no chain installed. By placing my head just in front of the chainwheel, I can sight along the chainwheel and see back to the rear hub, to see whether the chainwheel lines up exactly with the rear sprocket. If it doesn't, I re-arrange spacers or change the bottom bracket axle as necessary. Most older one-speed hubs, such as BMX, fixed-gear and coaster-brake hubs have a chainline of about 40-42 mm (centerline of the frame/hub to center of the sprocket.) The wider chainstays on mountain bikes often don't let you place a medium-sized chainwheel that close to the centerline of the bike, so there is a secondary de-facto standard chainline of about 52 mm for singlespeed mountain bikes. Stock MTB triple cranks usually have the outer chainring at around 52-57 mm; the middle is normally 47.5-50 mm. If you convert a cassette Freehub ® to singlespeed, you can put the rear chainline anywhere you want to match that of the desired chainring. There is more detailed information on chainline in my Chainline Article Centering Chainwheels Ideally, a singlespeed should have a frame with horizontal dropouts or track-style horizontal fork ends. With this type of frame, the chain tension is regulated by moving the rear axle back and forth in the fork ends. If the chain is too tight, the drive train will bind, perhaps only at one angle of the pedals (chainwheels are not usually perfectly concentric). It should be tight as it can be without binding. If the chain is too loose, it can fall off, usually at the most inconvenient possible time. Set the rear axle so that the chain pulls taut at the tightest part of the cranks' rotation. One at a time, loosen up each of the stack bolts, and tighten it back just finger tight. Spin the crank slowly and watch for the chain to get to its tightest point. Strike the taut chain lightly with a convenient tool to make the chainring move a bit on its spider. Then rotate the crank some more, finding the new tightest spot, and repeat as necessary. This takes a little bit of your hands' learning how hard to hit the chain, and how loose to set the stack bolts, but it is really quite easy to learn. Tighten up the stack bolts a bit and re-check. Tighten the stack bolts in a regular pattern, like the lug nuts on a car wheel. I start by tightening the bolt opposite the crank, then move clockwise 2 bolts (144 degrees), tighten that one, clockwise 2 more, and so on. Never tighten two neighboring bolts in a row. You may prefer to go counterclockwise, but try to get in the habit of always starting at the same place and always going the same way. This reduces the chances of accidentally missing a bolt. Once you have the chainrings centered and secured, adjust the position of the rear axle to make the chain as nearly tight as possible without binding. Notice how freely the drivetrain turns when the chain is too loose. That is how freely it should turn when you are done, but with as little chain droop as possible. Chain Tensioners for Vertical Dropouts If you're converting a '90s+ mountain/road bike to singlespeed, chances are that it has vertical dropouts, and you'll most likely need a chain tensioner of some sort. There are two different sorts of chain tensioners that you can use. Adjustable Tensioners Adjustable tensioners are set for the particular chain length/sprocket combination you will be using, and then tightened up to hold the pulley in the correct position. These are mainly intended for use on (yuck!) downhill bikes, and are designed to supplement a derailer to keep increase the chain tension, reducing the risk of accidental derailment. Some, such as the no-longer-available Tektro unit shown above, are also useful for singlespeeds. If you have a pure singlespeed, without a flip-flop hub, this type is adequate, and may even be very slightly more efficient, because there is no spring loading on the chain. I used to like the Tektro unit, but it proved a bit too delicate in practice, and clamping onto the chainstay isn't all that secure. I now prefer units that attach to the derailer hanger. Spring-Loaded Tensioners These are like partial derailers, with a single spring-loaded pulley. They attach to the derailer hanger of your dropout. Like many purpose-built singlespeed parts, they are often rather expensive considering how simple they are. If you plan to use different gear ratios, for instance with a flip-flop hub, a spring-loaded tensioner is the best choice. Gearing Gearing is a very personal matter, and it is difficult to give good specific recommendations for someone I haven't actually ridden with. The best gearing for you depends on a large number of variables, including: Your weight Your strength Your endurance How far you'll be riding in a day How hard you're willing to push How much baggage you'll be carrying The steepness of the terrain The nature of the road (or off-road) surface There is no magic formula for this, only experimentation will let you determine what gearing suits your needs. You might find my online gear calculator useful for comparing with your present gearing. Generally, for street use, with a freewheel, I would recommend a gain ratio of around 5-5.3, for instance, a 42 tooth chainring with a 16 or 17 tooth sprocket. You'll see other sites recommending "2:1" gearing, which typically gives a gain ratio of about 3.7. That's good if you are going to be riding off road on steep mountain trails, but a gear that low is maddening on the flats and particularly on pavement, because your speed will be limited by the tendency to "spin out." (The following is credited to BikeRadar) 1] Measuring steerer length The space a headset takes up is referred to as 'stack height' and tends to be around 42mm. Tange produces a model with a stack height of about 32mm that does the trick if your steerer is just a little bit too short. Measure the frame's headtube, say 130mm. Add 42mm for a normal headset, plus a few spacers just in case (four 5mm washers). Measure the total (192mm in this case) onto the fork column from the crown race seat upwards and mark. Thread the adjustable cup (preferably steel) down past the mark and cut, using it as a guide. Tidy the edges with a ﬁle, then back off the cup, cleaning the threads in the process. Blue threadlock on the top threads and locknut will prevent loosening. 2] Measure twice, cut once If using a threaded fork, check that it's long enough to ﬁt in the frame's headtube while allowing enough threads for the headset. With a threadless steerer, you'll need to check for the same length requirements. Assuming you've got a threadless fork with a diameter to match the frame's headtube, simply push it into the frame and slide the headset together, using the bearings, spacers and stem to determine what length will be required. Mark above the stem, then cut using a sharp hacksaw. Don't worry if you've cut a bit longer – this can be dealt with easily by adding an extra washer. Grease, assemble and adjust with no play, but allowing free rotation. 3] Check brake reach This is a critical measurement, especially if you're trying to get an older frame on the road. Make sure the brake pads can reach the rim braking surfaces without touching the tyre – if the pad wears through the tyre, it could lead to a sudden blowout. Measure from the centre of the brake bolt hole to the middle of the rim braking surface. You may find that it's a really old frame made for 27in wheels. If the old brakes don't provide enough reach, Shimano and Alhonga both make long reach versions of their dual pivot designs that will provide modern levels of braking power. Longer reach dimensions tend to be 47mm to 57mm or more when measured from the centre of the brake pivot bolt to the centre of the pad bolt in its lowest position. 4] Old skool Kool-Aids The Cinelli bar and stem pictured are a late '80s/early '90s track stem with big drop and a round criterium bar with a very high cool factor. These will deﬁnitely get you noticed in the urban singlespeed and ﬁxie crowd. These 'quill'-type units use a special bolt and wedge as a ﬁxing method – grease threads and mating surfaces along with the inside of the steerer and outside of stem. You can never over-grease, especially if the bike is used for winter training. They'll only work on a bike with a 1in compatible head tube and a threaded steerer, so if you have a 1 1/8in compatible frame and fork, you'll need to use a more contemporary clamp. You can still salvage a retro look if you happen to have an older standard bar diameter of 25.8/26.0. 5] Special controls Install your chosen brake levers (ours are Dia-Compe MX) in an appropriate and ergonomic position. Fixie riders will sometimes only run a front brake, but with a freewheeling singlespeed, two brakes are essential. Notice the barrel shaped cable end – different to the pear shape found on road cables. Other lever options include plug-in Dia-Compe or Tektro aero bar levers. Size and cut your brake cable housing to the correct length, making sure there's enough to accommodate turning the bars, and don't use indexing gear outers. Use ferrules where possible and apply a light grease or medium oil to the inners before stringing them through. Turn barrel adjusters all the way in, anchor cable ﬁrmly and put a crimp on the exposed end. 6] Modify the crankset A three-to-one ratio between chainring and cog seems to be the current favourite, providing a high enough top speed to keep up with trafﬁc, while allowing decent acceleration and mild climbing capability (it could also help build up a bit of upper body strength in the process). Choosing a 48-tooth ring with a 16-tooth cog gives you an 81in gear and both the ring and shorter bolts required are fairly common. The chainring bolt circle diameter for double cranksets is usually 130 for most brands other than Campagnolo, which is 135. A good bike shop should be able to order the Stronglight or TA aftermarket chainrings and bolts favoured by the custom-gear ratio crowd. Grease generously to avoid annoying creaks and ticks during the rainy season and tighten ﬁrmly. 7] Spaced out There are now several spacing kits available on the market, thanks to the popularity of singlespeed mountain biking. DMR and Surly come to mind, because both feature a series of attractive spacers that make use of old cassette cogs and lockrings. Alternatively, you could make your own with the old spacers, although not all cassettes will lend themselves to being taken apart. Some of the cogs will be attached to an alloy spider with rivets. Shimano's HG 50 series (105) and below, along with low to mid-range SRAM and Sun-Race cassettes, use separate all-steel cogs that are held in place by three long pins. These can be either unscrewed or ground down to free the cogs. The nylon spacers between the cogs can be used to ﬁll the gaps on the freehub, although an additional spacer or two might be called for. 8] Adjust chain length If you're really lucky, you could end up with a chain length that works without the use of a tensioner. This is more likely if you have the semi-horizontal or slightly longer drop out slots found on steel (and some alloy) frames. See if you can ﬁnd a link that matches up with the wheel in its most forward position. A SRAM Powerlink is safe to use and makes life easier, but the whole process can be tricky and involve a lot of trial and error. Invariably, you'll have to call on one of many chain tensioning devices on the market – the DMR STS, for example. Grease the threads and install the tensioner in place of the old derailleur. Two types are available: spring or no spring. Use the spring tensioned version and enjoy the peace and quiet of a single jockey wheel. 9] Check chain line Check that the chain line is reasonably straight. You can get away with a little left or right variation, especially with a 3/32in (derailleur type) chain. They're a bit more ﬂexible than a 1/2in by 1/8in pitch chain and will still run smoothly when climbing the chainring from a slight angle. It's nicer to get it right, though. Swap spacers as required, then lightly grease the spacers, cog and freehub lockring and tighten ﬁrmly without overdoing it (the serrations on the lockring should keep it from working its way loose). It's a good idea to place a metal washer against the inside edge of the freehub body as a ﬁrst space. This will keep the cog running true – the nylon spacers can get distorted if the lock ring is overtightened. 10] Make final tweaks Take a test ride to locate any small problems and iron them out. Check for pedal overlap, adequate braking power and brake lever placement. Install any ﬁnal parts: pedals, a cool bell, maybe some eco-splash guards fashioned from plastic milk jugs and zip ties! Assess the handling – a small variation in fork offset shouldn't drastically change the behaviour of the bike. Most important is headset adjustment. Ensure this is not too tight because it can cause the headset to get indented and interfere with the balance of the bike. After a couple of rides, re-check the chain and tensioner. Keep the bike clean if you can and make a habit of checking critical components for early signs of failure like small cracks. Other Information and Links I hope you got all the information you needed from Sheldon and BikeRadar. Below are some links and videos to show you more on how to convert your old road bike into a fixed gear or single speed bike. Credit goes to: Sheldon Brown & Bike Radar. Thanks. Psyclist.