Fixed Gear for the Road
(Old Version)
This article has been split into two parts,
but I'm leaving this version in place for the sake of old links. See:
Fixed Gear Conversions
[Braking] [Chainline] [Chain Tension] [Chain Types] [Converting a Bike to Fixed Gear] [Fixed Gear Road Bicycles] [Gearing] [Hubs] [Mounting/Dismounting] [Pedals] [Track Bicycles] [Vertical Dropouts]
I still feel that varable gears are only for people over forty-five.
Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer?
We are getting soft...As for me, give me a fixed gear!
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--Henri Desgrange, L'Équipe article of 1902
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What is a Fixed-Gear Bicycle, and Why Would You Want One?
he oldest and simplest type of bicycle is the "fixed-gear" bicycle. This is a single-speed bike without a freewheel; that is, whenever the bike is in motion, the pedals will go around. You cannot coast on a fixed-gear machine.
any enthusiastic cyclists ride such bicycles by choice, at least part of the time. Why would anybody do that? It is not easy to put into words. There is an almost mystical connection between a fixed-gear cyclist and bicycle, it feels like an extension of your body to a greater extent than does a freewheel-equipped machine. If you are an enthusiastic, vigorous cyclist, you really should give it a try.
There are many reasons, including: fun, fitness, form, feel & 'ficciency!
Fixed for Fun
t takes a bit of practice to become comfortable on a fixed gear. Most cyclists, trying it for the first time, will automatically try to coast once the bike gets up to a certain speed. The bike will not allow this, and it is disconcerting. It takes a couple of weeks of regular riding to unlearn the impulse to coast, and become at ease on a fixed gear.
It is worth going through this learning experience, however, because once you do so, you will discover a new joy in cycling. When you ride a fixed gear, you feel a closer communion with your bike and with the road. There is a purity and simplicity to the fixed-gear bicycle that can be quite seductive. Somehow, once you get past the unfamiliarity, it is just more fun than riding a bike with gears and a freewheel! If you won't take my word for it, read some Fixed-Gear Testimonials.
Fixed for Fitness and Form
iding a fixed gear on the road is excellent exercise. When you need to climb, you don't need to think about when to change gears, because you don't have that option. Instead, you know that you must just stand up and pedal, even though the gear is too high for maximum climbing efficiency. This makes you stronger.
If you have the option of gearing down and taking a hill at a slow pace, it is easy to yield to the temptation. When you ride a fixed gear, the need to push hard to get up the hills forces you to ride at a higher intensity than you otherwise might. Really steep hills may make you get off and walk, but the hills you are able to climb, you will climb substantially faster than you would on a geared bicycle.
When you descend, you can't coast, but the gear is too low. This forces you to pedal at a faster cadence than you would choose on a multi-speed bicycle. High-cadence pedaling improves the suppleness of you legs. High rpm's force you to learn to pedal in a smooth manner--if you don't, you will bounce up and down in the saddle.
Most cyclists coast far too much. Riding a fixed-gear bike will break this pernicious habit. Coasting breaks up your rhythm and allows your legs to stiffen up. Keeping your legs in motion keeps the muscles supple, and promotes good circulation.
Fixed for Feel
fixed gear gives you a very direct feel for traction conditions on slippery surfaces. This makes them particularly suitable for riding in rainy or icy conditions.
This same feel for traction will help you learn exactly how hard you can apply your front brake without quite lifting the rear off the ground. Most fixed-gear riders only use a front brake--a rear brake is quite unnecessary on a fixed-gear machine.
Because you are more solidly connected to the bike, you have better control of it in bumpy conditions or in difficult corners.
On any road bike, the rider must learn to un-weight the saddle to ride over bumps. Most cyclists coast to do this. A fixed-gear rider will learn to "post" over bumps without breaking stride.
Fixed for (e)Fficiency
fixed-gear bike is considerably lighter than a multi-speed bike of comparable quality, due to the abscence of the rear brake, derailers, shift levers, and extra sprockets. A fixed-gear bike also has a substantially shorter chain.
A properly set-up fixed gear has a perfectly straight chainline. This, plus the abscence of derailer pulleys, makes a real improvement in the drive-train efficiency, an improvement you can feel.
any people think of fixed-gear bikes and track bikes as synonymous, but they aren't
Track bicycles are designed for use on velodromes (bicycle tracks). Some riders do ride them on the road, but they are less than ideal for road use.
Track bicycles are set apart from road bicycles by more than the fact that they have a fixed gear.
Track bicycles do not have brakes. Brakes are un-necessary on tracks, since everybody is moving in the same direction, and none of the other bikes you are riding with can stop any faster than you can. (Most tracks forbid the use of bikes that have brakes, as a safety measure!)
It is possible to fit a brake to some track bikes, but it is often quite difficult, due to the extremely tight frame clearances. Extremely short-reach brakes are needed. Track bike fork blades are usually round instead of oval, as those of a road bike are. This makes them stiffer and more rigid laterally, a good thing for hard out-of-the-saddle sprinting, which can apply considerable side loads. Unfortunately, they are less rigid front-to-back, so if you fit a brake, the fork may flex objectionably when the brake is applied.
The frame geometry of a track bike is also different from that of a road bike. Since tracks don't have bumps or potholes, they are built stiffer, with more upright frame angles. This is good for maneuverability, but causes them to ride harshly on real-world pavement.
In addition, track bikes have very tight tire clearance, since there is no reason to use any but the narrowest tires on the track. This can limit your choices for on-road use.
Track bikes don't have quick-release wheels, making it harder to fix a flat on the road.
Track bikes don't permit the mounting of fenders, limiting their usefulness in sloppy conditions.
Some riders do prefer to ride track bikes on the road, especially those who are or were into track racing, and have become used to the feel of a track bike. Track bike riding has attained cult status in New York City, in particular.
If you're interested in track racing, check out Mike Gladu's "The 'drome" site
Fixed-Gear Road Bicycles
espite the coolness factor of true track bikes, a fixed-gear road bicycle is what I would recommend for the road cyclist in search of the benefits of fixed-gear riding.
This would typically be an older road bike, modified into a fixed-gear machine. Most older "ten-speeds" are good candidates for this sort of modification.
These bikes have the appropriate geometry for comfortable road riding, come with brakes, quick-release wheels, fender clearance, sometimes even water-bottle braze-ons.
Converting multi-speed bikes for fixed-use.
Hubs for Fixed-gear Bicycles
Track Hubs
here are three ways you can go, as far as hubs are concerned. You can use a track hub, a freewheel hub, or a flip-flop hub.
The best set-up for a road fixed-gear is to build up a new rear wheel, using either a track hub or a flip-flop hub.
Track hubs have a stepped thread. The main thread that the sprocket screws onto is the same as that of a normal freewheel hub. Outboard of this, is another threaded secton of slightly smaller diameter. This thread is a left (reverse) thread, and a special lock ring screws onto it. After you screw the sprocket on in the normal manner, and tighten it down securely, the lock ring screws down so that it presses against the outer surface of the sprocket. If the sprocket should start to loosen up, it will try to turn the lock ring counter clockwise...but that only tightens the lockring. As a result, the sprocket cannot be unscrewed by the chain, no matter how hard you fight the pedals.
lip-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 standard freewheel. It is possible to find them with track threading on both sides, but not easily.
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. Ideally, the freewheel sprocket would be one or two teeth larger than the fixed sprocket.
You would ride with the fixed gear most of the time (I hope!) and save the freewheel for longer rides, or for getting you home when you are tired. Having the freewheel a bit 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, other sizes may be hard to find, especially for 3/32 chain.
If you are going to use a flip-flop hub with a freewheel, you should have two brakes on the bicycle.
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
he cheapest way to convert a multi-speed bicycle into a fixed gear is to use the original rear hub, assuming that it is made for a conventional threaded freewheel. A fixed sprocket will thread right on, but there is no provision for a left threaded lock ring.
If you go this route, it is a good idea to use LocTite or a similar thread adhesive. You can use an old lock ring from a British-threaded bottom bracket as an additional safety measure, it is the same thread.
Although you can just screw on the sprocket and put everything together, the chain line will probably be incorrect. If you go this route, you will probably need to re-arrange spacers on the axle to correct the chain line, then re-dish the rear wheel so that everything will track correctly.
I should mention that there are those who say you shouldn't use a lockring. This theory is based on the fact that if the chain should come off the chainwheel and get caught, a sprocket without a lockring will just unscrew, rather than locking up the rear wheel.
My feeling is that it is better to use a lockring so that you can rely on being able to slow the bike down with your feet, especially if you ride with only one brake.
Frames for Fixed-Gear Conversion
Road Bikes
t is very desirable that a frame for fixed-gear use have "horizontal" rear dropouts: that is, the slots in the frame that hold the rear axle should run in a more-or-less horizontal direction. This allows you to move the axle back and forth as needed to adjust chain tension. This makes things much easier than if you try to convert a newer bike with vertical dropouts.
The most desirable bikes for fixed-gear conversion are 1970's road bikes. These usually have horizontal dropouts, and usually don't have unsightly shift-lever bosses. Frames of this era also tended to have more generous tire clearance than newer sport bikes, providing more versatility in the choice of tires, and the use of fenders.
Three Speeds
ld three-speeds can also make quite satisfactory fixed gear bikes, particularly English ones. The rear triangle is already just about perfect for a track hub, they usually have 110 mm spacing. The better English 3-speeds had pretty nice riding frames, and can be very pleasant bikes for not a lot of money.
If you replace the 590 mm (26 x 1 3/8") wheels with 622 (700C) wheels, the bottom bracket gets raised a useful amount, providing good ground clearance. Using the larger wheels also allows you to install a better, shorter-reach brake caliper.
Mountain Bikes
fixed-gear mountain bike may be the ultimate in heavy-duty urban transport, and, if you are adventurous enough, you can even take it to the woods. Mountain bikes tend to have adequate ground clearance, although most, alas, have vertical dropouts.
I have an old Bridgestone CB-3 set up for nasty winter conditions, with a 28/15. This gives a nice low gear, a 3.63 gain ratio (49" / 3.88 m) which will take me as fast as I care to go when the streets are snowy. A fixed gear this low makes the brake almost un-necessary: such a low gear lets me slow the bike down qickly by resisting, especially considering that it can't go very fast.
I have set up a couple of mountain bikes with flip-flop hubs, so that I get a fixed gear on one side and two different freewheel gears on the other. This is done with a double chainwheel and a two-speed freewheel. (The freewheel is actually an old 5- or 6-speed freewheel with 3 of the sprockets replaced by spacers.
In front, I have a 42/52 double, which I use with a 19 tooth fixed and a 20/30 freewheel. This gives 3 usable combinations:
| | | Gain | Inches | Meters
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| 52/19 | Fixed | 5.45 | 71.2 | 5.70 | General road use
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| 52/20 | Free | 4.90 | 64.1 | 5.13 | Road...when I'm tired, or hilly areas.
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| 42/30 | Free | 2.64 | 34.4 | 2.75 | Off-road.
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The 52/30 and 42/20 combinations are not usable due to chain length. I change gears manually...yes, I have to stop to do it, so I don't do it that often.
Bruce Ingle, a fellow member of the Charles River Wheelmen, has gone me one better, and made a triple-fixed mountain bike. He used a Shimano cassette hub, which he immobilized by brazing the ratchet mechanism together. I am a bit nervous as to the long-term prospects for this hub, in particular the connection between the freehub body and the hub shell, but I think I will have to copy his setup. He's got:
| | | Gain | Inches | Meters |
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| 48/20 | Fixed | 4.65 | 62.4 | 4.99
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| 42/26 | Fixed | 3.13 | 42 | 3.36
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| 36/32 | Fixed | 2.18 | 29.3 | 2.34
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Vertical Dropouts
ost 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.
You cannot use a derailer on a fixed gear bike, even as a chain tensioner, because when you resist the rotation of the pedals, you would bend the derailer.
Even the chain tensioners used for downhill mountain bike racing are not strong enough to withstand the stress of resisting the pedals. These tensioners have to clamp on to the chain stay, which is more or less round. There is no way to make one that would be secure, short of installing some sort of brazed-on fitting.
Fortunately, most "vertical" dropouts are not exactly vertical, they usually have a bit of a slant to them. 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: http://www.peak.org/~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.
Frames built originally to be used with 5-speed freewheels usually have 120 mm spacing between the rear dropouts. Fixed gear hubs are commonly avaialable in this spacing, although they are more commonly found in the narrower, 110 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 fixed gear hubs generally come only with solid axles, not quick relase.
Drive Train
1/8" or 3/32" Chain?
any track bicycles use a wider chain than is common on multi-speed bicycles. Derailer-type chain has a nominal internal width of 3/32". Single-speed bicycles, including most track bicycles, use the wider 1/8" size. You can buy fixed-gear sprockets in both sizes.
(Some people mistakenly refer to the width as "pitch", speaking of "road pitch" or "track pitch". This is a malapropism. The pitch is the distance between the rollers, and all modern bicycle chain has the same pitch, 1/2"/12.7 mm.)
I would strongly advise using the 3/32" (derailer) size. Not only is it more compatible with your existing chainwheels, but it is actually more durable. This is because you cannot get 1/8" chain in the modern "bushingless" design.
For the true retro fan, another option is 1" x 3/16" chain. This used to be common on track bikes. This requires special sprockets with only half as many teeth as standard 1/2" pitch sprockets. Serious old-time trackies used "block" chain, which had no rollers. This is no longer available. Roller chain is still sometimes findable in this size.
Even more obscure is the 10 mm pitch chain promoted by Shimano a few years back. The idea was to save weight by making everything littler. An idea whose time never came.
since December 26, 1995 -->
Copyright © 1997, 2008 Sheldon Brown
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