Whosa what now?
A fixed gear bicycle (fixer, fixie, fix) is a bicycle that does not have a freewheel mechanism. A freewheel is a ratcheting device that allows the rear wheel to roll forward without moving the cranks. Without this component, if the wheel is moving, the pedals are moving, and vice versa. You cannot coast, and you cannot rotate the pedals without rotating the wheel in the same direction. The pedals are literally chained to the wheel. They usually only have one gear.
Why would anybody want this type of bike? Every person has a story, but here are four or so of the main reasons:
- Durability: Since there is a minimum of moving parts, there are less things to go wrong. A fixer will roll through snowy, muddy, gritty streets far longer than your average geared bike.
- Ease of Maintenance: Preventing disaster is easier for the same reason as #1. Great for those of use who clean our chains once a year.
- Ease of Operation: No worrying about if you're in the right gear, just get on and ride.
- Novelty: It's different than riding a regular bike, and makes biking a totally new experience. Plus, if you're good, you can even ride without brakes.
- Peace and Quiet: No fishing-reel freewheel noises, no clanky shifting. Just the sounds of tires on rubber and your own breath.
If you want a fixed gear bike, you can just go buy one, ready to ride. But, you should be aware, fixed gear bicycles are NOT common by any means. Your average Local Bike Shop (LBS) probably won't have one that isn't a track bike, and thus somewhat uncomfortable geometry for rides that are more than a mile or two. Most people who seek a fixer either buy one over the internet or else build it themselves. Building your own is very simple, and is often referred to as "converting" a geared bike to a fix. Building or converting your own bike is generally recommended by the cycling crowd, as it forces you to become intimately familiar with how your bike works, and how to repair it. Converting one is not only relatively inexpensive, it saves a salvageable bike from a trip to the dump. Plus, it's pretty easy. So, since we're cheap and/or admire the idea or salvaging a frame, we'll convert.
Autobots, transform to Fixed Gear Bicycle
To build your fixed gear bike, the first thing you need is a frame. A good source of cheap frames is your local thrift/consignment store. Also check out the classified ads, garage sales, and dumpsters. Find a bike that fits well. Ride it around (if you can) and see how it feels. Check it for dents and bends. Don't worry if it's a mountain bike frame or a road frame or whatever. If you like it, it will like you. $40 will usually be more than enough.
Aside from fit, the main thing that you are looking for is horizontal (or nearly horizontal) rear dropouts. These are the slots in the frame that the rear axle slides through, and hold the wheel to the bike. Most road bikes that are from the late 80's and earlier have these. And, luckily enough, most bikes that you'll find at a thrift store are old road bikes. It's as if this was fate.
If the bike/frame you like doesn't have horizontal dropouts, you may still be able to get it done. Whether you have your heart set on fixing a frame with vertical dropouts because you love it or you already own it, you can probably get it to work. It just won't be as easy. But we'll get to that later.
Congratulations! You have a bicycle and/or frame. Let's examine what we have in stock. The following items are necessary to build a fix, so you should either already have them on the bike, or else buy them from a store or steal them or something:
- Various Structural requirements:
- Saddle - The part you sit on.
- Seatpost - Sticks out of the frame, holds the saddle.
- Seatpost Collar - Secures the seatpost to the frame.
- Fork - Holds the front wheel.
- Front Wheel - We ain't building a unicycle.
- Rear Wheel - Either the one that came with the bike or a new one, that's for the next section.
- Tires and Tubes - Keep the wheel rims from hitting the road.
- Headset - Attaches the fork to the frame, lets you steer.
- Stem - Attaches the handlebars to the fork.
- Handlebars - Someplace to put your hands to help steer.
- Front brake - Lets the novice fixer stop.
- Drivetrain requirements:
- Pedals - Step on these to make it go.
- Cranks - These attach the pedals to the rest of the bike.
- Bottom Bracket - This connects the cranks to each other and the frame. If your cranks are already installed, you don't need to worry about this. Much.
- Chain - The transmission. Don't get too attached to it.
Now, if you're paying attention, you may noticed that a few things are missing from that list that you usually associate with a bicycle. Here's where we address those "missing" parts:
- The rear brake is missing, dummy! What kind of fiery death are you leading me too? - Rear brakes on bicycles give less than 25% of the stopping power when two brakes are used. On a fixed gear, since you also brake by resisting the pedaling motion, this is effectively a rear brake already, like the coaster brake you might have had on your bike as a kid. Thus, another rear brake is redundant. You can keep it if you have it, but it's not necessary.
- What about chainrings and cogs? What is that chain going to attach to? - Chainrings usually come with cranks, so you probably already have those. Cogs are a special buy and will be covered later.
Stripping or How to Fill a Shoebox With a Bunch of Rusty Junk.
This is the fun part. All the stuff that isn't on the list? Take it off. This includes the front and rear derailleurs, shifters, rear brake (optional), and associated cables. Use (just about) any means necessary. Cut it off, unscrew it, use a blowtorch. Just don't bend or break necessary parts of the frame, or any other vital components. Have fun. If the stuff looks like it's in marginally good shape, hock it on eBay, or donate it do your LBS and generate some good karma. If you think it might be vintage, save it and contact a vintage bicycle person. If it's crap, junk it.
Now, we can tackle the most difficult part of the process: the rear wheel
The Mysterious Rear Wheel
If your formerly geared bike came with a rear wheel, you have two options: buy a new one , or just try and use it, regardless. Buying a new rear wheel isn't the cheapest way to go, but it can spare you a lot of headaches, and it's safer.
The difference between a fixed gear wheel and a regular wheel is that the fixed gear wheel has no freewheel. Remember that? The ratcheting thing? This means that the cog and the rim are directly connected. No coasting. So, the cog basically just screws onto the hub of the wheel. Nice. But if the cog screws on, how do they keep it from screwing off when you put opposite pressure on the pedals? The lockring.
This is what makes a fixed gear hub special. There are TWO types of threading on it. The first, closest to the spokes, is a slightly larger diameter than the other, which sticks out off of the edge of the first. So, a fixed hub has a type of stepped, threaded appearance on at least one of the sides. The other thing isn't quite as apparent: The second threading, the smaller one, is reverse threaded. This means that the standard "righty-tighty, lefty-loosey" maxim we've been taught since childhood has been reversed. Egads!
They do have a reason for this treachery. The cogs screw on to the right. After this, the lockring screws on to the left. So, when you mash on the pedals going forwards, it pulls the cog to the right, tightening it. But, if you put reverse pressure on it, it pulls the cog to the left, which would loosen it, except the lock ring is pulled along with the cog, and lockring tightens against the cog, so it cannot unscrew. Foolproof.
To install the cog, tighten it on (careful not to cross-thread it) by hand. Then, with the wheel installed in the frame, tighten the chain around the new cog and rotate the wheel backwards until the chain overlaps itself and starts to act as a wrench. You may want to put a rag between the rest of the chain and the frame around the bottom bracket to prevent scratching. Keep rotating the wheel backwards until it is hard to pull much further. The cog is on.
To get the lockring on, just screw the lockring on to the left (opposite threading) by hand until it's tight. Then, using a lockring spanner, tighten it further. If you don't have a lockring spanner (?!) then you can just put a screwdriver in the notch of the lockring, and tighten it by hitting it with a hammer. Not the best way, but it works, and you don't have to buy a new tool.
So, if you're going the buy-a-new-wheel route, you'll have to shell out around $60 minimum for a new wheel, cog, and lockring. Keep in mind, this is in the world of new bicycle parts, where paying $200 for just a pair of pedals is not unheard of. You're getting off easy. If you decide that $60 is too much for you, and you enjoy taking your life in your hands, you can convert your existing rear wheel to a fix. This type of wheel is known as a "kludge," or "suicide hub" and there are many websites that give information on how to make one. However, every single one of these has a disclaimer that if you hurt/maim/kill yourself riding one, it's your fault. Be forewarned.
The second most difficult part. Once you've got your rear wheel all set up, put it on the bike. You'll probably have an excess of chain, so you can remove links as needed to get it to be taut when the chain is on your desired front ring and rear cog. Now, tighten up the nuts that hold on the rear wheel, and take a look down the chain from cog level. This view of the chain should demonstrate how much the chain travels right or left as it goes from the cog to the chainring. If it is straight from the cog to the chainwheel, you are all set. If it's pulled off to the side by more than 1mm (or 1/16th of an inch to those who REFUSE to learn a measuring system that makes sense), you'll need to adjust your chainline.
Adjusting chainline can be done at two locations, of course: the cog or the chainring.
At the chainwheel end, you can change a number of things to adjust where it will pull the chain. Bolting the chainring on the opposite side of the crank spider, using chainring spacers, and using a different chainring (if it has more than one) are all easy, cheap ways to move your chainring around to the left and right. If you are desperate for a nice change, you'll have to remove your cranks (requires special tools), remove the bottom bracket (requires special tools), and get a new bottom bracket with a different spindle length or just a new bottom bracket spindle and install these (special tools required), and reinstall your cranks. As you can tell, this is a difficult and somewhat expensive process if you don't already own the tools needed. Luckily, your LBS will probably be happy to help you for a more reasonable price. If you want a perfect chainline that looks like the bike was built for, this is the way to go.
At the cog end, you can do very little. The only thing you can really do is push the cog a little bit further out from the hub with a spacer, such as a large washer or an old bottom bracket lockring (availabe at your LBS, of course). Another possible alternative is to adjust the spacers on the axle itself. This will push the entire wheel to the left and right, so you have to watch your tire clearance. Moving the wheel around will affect the look of the bike drastically, and may affect the ride itself. Most people would recommend moving the chainring instead, but if you've already reached the end of your wallet and need to get a little bit more, try moving the wheel. Don't say I didn't warn you.
Wait! What if my bike has vertical dropouts?
If your bike frame has vertical dropouts, you must be VERY willing to try some radical stuff. Basically, all of these methods require being a little adventurous with a file and/or a grinder. If you screw up, whatever part you are working on is basically worthless. This is why I recommend using extremely cheap/free frames and parts.
The first thing you need to do is find the magic ratio This is the special combination of chainring size, cog size, and chain length that will allow you to have a taut, or nearly taut chain when the wheel is in the rear dropout. Try various chainrings, and various cogs. It can be expensive to try all of this stuff, but a good bike shop should be happy to let you "try on" various components. A friend or acquaintance is also good. Further, there are a number of online calculators that use measurements of your chain stay length to calculate possible ratios.
Now, if you have a magic ratio that is fairly tight, you could just quit there. However, as the chain gets used, it will stretch. Not a lot, but enough to eventually give you some slack in your chain. So, you can either keep buying new chains every couple months (which some people do, if they REALLY love the frame), or try to add some adjustability.
Adjustability can be added at roughly two spots: The axle, and the dropout.
The axle is the safer of the two spots to work. What you want to do is grind or file down one face of the axle on both sides. This should make the end of the axle look like a circle with a flat spot, instead of just a circle. How much of the axle you flatten is up to you. With the flattened axle, you can rotate the axle in the rear dropout to obtain a little bit of horizontal play. Alternatively, if you have quick-release axles, you can cut off the ends of the axle housing so that only the quick release skewer itself passes through the dropouts. This will give you a greater amount of horizontal play, since the skewer is a lot narrower than the axle, but it places a lot of stress on the skewer. Both of these methods have been used by Sheldon Brown successfully.
Okay, it's done. Now what?
Check to make sure everything actually works. Pick up the rear wheel, and rotate the pedals. Make sure the chain stays on. Try and turn the pedal back the other way. There should be very little "slack" in the chain, making the resistance nearly instantaneous. You should be able to resist the existing rotation enough to reverse the rotation of the rear wheel. Make sure your front brake works well. Make sure your pedals and seat are installed correctly. And just to be sure, you'd probably better go to your LBS and have them give it a once-over.
Starting to ride a fix is basically the same as a regular bike, so what's to learn? There are two things you need to watch out for. When turning at slow speeds, your feet may come into contact with the front wheel. It's just something you have to watch out for. And when turning at high speeds, the inside pedal may come into contact with the ground. These two problems are called foot overlap and pedal strike respectively. Learn them, know them, avoid them.
Other than that, ride your bike! Ride it to work. Ride it across your state, province, or country. Ride it in a small race. The worst thing to do to a bicycle is ignore it. So ride!