Fixed Gear for the Road
(Old Version), Part 2
This article has been split into two parts,
but I'm leaving this version in place for the sake of old links. See:
I still feel that variable 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!
--Henri Desgrange, L'Équipe article of 1902
erailer bikes can work fairly well even with the chain running at a considerable angle, but this should not be done with a fixed-gear setup. It is quite important to get the chain line 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 chain wheel, I can sight along the chainwheel and see back to the rear hub, to see if 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.
Usually, on a bike that came with double chainwheels, the inner chainwheel will be more in line with the rear sprocket. If you wish to make the bike a pure fixed gear, you can buy a set of shorter "stack bolts" (the 5 bolts that hold the chainwheel(s) to the crank spider). You may find it easier to locate these in a shop that deals in BMX bikes.
There is more detailed information on chainline in my Bicycle Glossary's Chainline Entry
he chain tension on a fixed gear is quite critical
, and 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, which is quite dangerous
on a fixed gear.
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 chain ring 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. My standard pattern is to 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 drive train 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.
ear choice for a fixed gear is a very personal matter, and will depend on your style, your goals, and the terrain you ride in.
I live in New England, with small rolling hills. For a bike with normal road-type wheels and 165 mm cranks, I find that 42/15 suits me best. This gives a gain ratio of 5.77 (75.6" / 6.05 m gear). This is low enough that I can make it up the hills where I usually ride, but high enough that I can go reasonably fast down the other side.
Racers using a fixed gear for winter training usually like a considerably lower gear to improve their spinning technique.
Those who live in the flatlands will likely prefer something substantially higher. When I visit my sister in Illinois, I flip my wheel around so that I can use the 42/14, a gain ratio of 6.18 (81.0" / 6.48 m).
Generally, the higher the gear, the more fun the ride, as long as your gear is low enough to let you climb the steepest hill you need to climb.
Time-trialists often prefer something higher yet. (Many British time-trialists prefer a fixed gear for these road events.) Beryl Burton, probably the greatest time-trialist in history, used a fixed gear almost exclusively. If I recall correctly, she usually ran a 52/14 or 52/13!
The higher your gear, the more desirable it is to have a brake
on your bike. There are two reasons for this:
- Just as a low gear lets you apply a higher forward force to the tire for hill climbing, a low gear also allows a greater resistant force at the tire for the same amount of leg effort.
- The lower your gear, the lower your maximum speed will be, and if you're not going so fast you don't need as powerful a brake.
If you plan to do skip stops on a regular basis, you might also consider the number of skid patches your chosen gear ratio will create.
he most important characteristic to look for in choosing pedals for a fixed-gear bike is good ground clearance. You should also choose pedals that are easy to get in and out of, because both operations are somewhat complicated by the motion of the pedals.
Generally, I recommend using whatever pedal/shoe system you are most used to. Getting used to fixed-gear riding is challenge enough without also trying to get used to a new pedal system at the same time!
When I used to use toe-clips and straps, I fit two toe straps to each pedal, partly because they help keep my feet in better alignment (since I don't use cleats) and partly for safety. Toe straps can get highly stressed on a fixed-gear bicycle, and if they break, unpleasant consequences may ensue.
Sometimes, novice fixed-gear riders will try to use plain pedals with no form of retention system. I strongly advise against this. Riding fixed with plain pedals is an advanced fixed-gear skill, only recommended for experienced fixed-gear riders.
iding a fixed-gear bicycle requires proper mounting technique. Many cyclists have bad mounting habits, such as swinging the leg over on-the-fly, or starting up by shuffling their feet against the pavement. These techniques work even worse on a fixed-gear bicycle than they do on a freewheel machine.
Getting your first pedal into the proper forward-and-up position is a bit trickier with a fixed gear, since you can't just spin the pedals backward. The trick is to put your foot on the pedal, then lift the rear end of the bicycle up so that you can turn the pedals.
I used to lift the bicycle up by the edge of the saddle, but I damaged a Brooks Pro that way--the rivets that held the leather top to the saddle frame pulled out from being stressed in this unanticipated direction!
My friend Osman Isvan recently taught me a much better technique. The trick is to straddle the bike, put one foot on a pedal, lock up the front brake [another good reason to have one -- John Allen] and press forward on the handlebars. The forward force on the bars will lift the rear wheel enough to let you revolve the pedal to where you want it.
ou can dismount in the normal manner from a fixed-gear bicycle, but advanced fixed-gear riders might enjoy learning a special, very cool-looking dismount that can only be done from a fixed gear.
Instead of getting off to the side of the bicycle, the fixed-gear rider can go straight off the back. This technique works best if you ride with clips and straps, but if you are really proficient in disengaging from clipless pedals, try it at your own risk.
As the bicycle slows to near walking speed, disengage your left foot, then wait for the right pedal to get to the bottom of its circle. As the right pedal starts to rise, straighten your right leg and let the motion of the pedal lift you up. Let go of the handlebars, let the saddle move forward between your legs, and put your left foot on the ground. As the bike goes ahead, grab it by the saddle.
It takes a bit of courage to try this, but it is actually very easy to do. It is also extremely impressive to watch. When executed properly, it is very smooth, and you can go from riding to walking in a single fluid motion, without ever coming to a stop.
ome fixed-gear riders ride on the road without brakes. This is a bad idea. I know, I've tried it. If you do it, and have any sense of self-preservation at all, it will cause you to go much slower than you otherwise could, every time you go through an intersection, or pass a driveway. The need for constant extra vigilance takes a great deal of the fun out of cycling.
You really should have a front brake. A front brake, all by itself, will stop a bicycle as fast as it is possible to stop. This is true because when you are applying the front brake to the maximum, there is no weight on the rear wheel, so it has no traction.
One of the wonderful things about fixed-gear riding is that the direct feel you get for rear-wheel traction teaches you exactly how hard you can apply the front brake without quite lifting the rear wheel off of the ground.
This is a very valuable lesson for any cyclist who likes to go fast; it could save your life.
There is really no need for a rear brake on a fixed-gear bicycle. By applying back-pressure on the pedals, you can supply all the braking that the rear wheel really needs. In fact, it is fairly easy to lock up the rear wheel and make it skid, unless you are running a rather high gear.
Some fixed-gear fans make a point of not using their brake except in an emergency. I am not sure that this is a good idea. Heavy-duty resisting is widely reputed to be bad for your legs, and to be counterproductive for building up muscles and coordination for forward pedaling. Google for "eccentric contraction" for more on this topic. Eccentric contraction is reputed to cause micro-tears to your muscle tissue, so it actually weakens your muscles, unlike other forms of exercise.
This is a lot like car drivers who use their transmission and clutch to slow down, even though the car has a special set of parts made for the exact purpose of slowing down. Brake shoes are cheaper to replace when they wear out than clutches are.
[Exercise physiology is a relatively new science. Micro-tears in muscles are now known to initiate strengthening. Common muscle-building exercises -- weightlifting, pushups, sit-ups, Nautilus and Cybex machines, etc. use eccentric contraction -- you lift the barbell, or your body, or pull on a lever, then lower it down. But the number of repetitions in muscle-building exercises is much smaller than in cycling, typically only 2 or 3 sets of 10 repetitions, rather than thousands per hour of cycling. Hard resisting is probably a bad idea for the same reason as low cadence. High stress repeated too many times leads to overuse injury, and will deplete rather than build muscle. -- John Allen]
rakeless riders generally need to master a technique called the "skip stop." This is a way that you can actually lock up the rear wheel using your legs alone.
- If you lock one leg at the bottom of the pedal stroke, as the pedal rises it will start to lift your body upward.
- When the cranks get horizontal, pull up on the front pedal, while pushing down on the rear one.
- Because your body will have acquired upward momentum, when you yank up with the front foot this will temporarily partially unweight the rear wheel, making it possible to initiate a skid.
Since sliding friction is less than sticking friction, once the tire starts to skid, you will generally be able to maintain the skid until you've stopped or at least slowed down as much as you want to.
You have to really want to do it, you can't be tentative! It's easier when you're going faster.
The lower your gear , the more effectively you can "brake" by resisting with your legs.
Despite what some folks will tell you, you can not stop nearly as short this way as you can by using a good front brake.
See my article on Braking and Turning for a detailed explanation of this.
should warn you that there are three dangers related to fixed-gear bicycles that are not a problem with freewheel bicycles. Used and maintained properly, fixed gear bicycles can be as safe as any, but you should be aware of the three danger areas:
t is never a good thing to strike your pedal on the ground while cornering tightly. On a freewheel bike, you can coast though the corners with your pedals horizontal, thus avoiding any chance of striking. On a fixed-gear machine, you don't have this option.
If you do bang a pedal on a fixed gear, the pedal can lift the rear wheel off the road, and down you will go. This has never happened to me, but it is something to bear in mind.
How much of a problem this is will depend on your bottom bracket height, crank length, and the design of your pedals.
Most of my fixed-gear bikes have 165 mm cranks,which give a bit more ground clearance than the 170 mm's usually used on road bikes. I also make a point of using pedals that don't stick out too far.
[Avoiding a pedal strike is one reason not to follow Sheldon's usual advice to keep the bicycle in line with your body when cornering hard. If you lean your upper body toward the inside of the turn, the bicycle will not steer as well, but on the other hand... -- John Allen]
Derailment and Wheel Lock
hrowing a chain on a freewheel bike is no big deal, but it can be very dangerous on with a fixed gear. If the chain comes off of the chainwheel, it can get hung up or even loop around the rear sprocket, and can cause the wheel to lock up. If this happens while you are leaned over in a turn, you will almost certainly crash.
This is prevented by making sure that your chainline is straight, and that your chain is adequately tight.
Catching Fingers, Trousers, Shoelaces
he other danger of fixed-gear bicycles is at its greatest when the bike is in a repair stand. If you hand-pedal it and then accidentally have a finger an article of clothing come into contact with the chain or a sprocket, the momentum of the wheel will keep the drive train rolling. You can lose a finger that way.
Sorry to gross you out with these photos, but this is a real danger!
Likewise, when riding, if you are wearing floppy pants, or have an un-tied shoelace, you may get your clothing caught in the drivetrain. On a freewheel bike, this it is a minor inconvenience. You have to coast, then pedal backward to release your clothing. The worst that will happen is that your clothing will get soiled.
With a fixed gear, you have no such option. If you catch a shoelace, it will get torn off or your shoe. If you catch a trouser leg, you can really get hurt.
by John Allen