Lots of old cheap childrens' bikes have coaster brakes. It's absolutely essential, however, that the parts be identical, or else the brakes could fail at exactly the wrong time, putting the rider's life in danger. If all parts are reasonably in good repair, or if identical good parts can be replaced through inexpensive purchase or cannibalization, the overhaul can continue. Otherwise, it's best to purchase a new wheel.
So if you finally wear out bearings or whatever, this might be an easy answer, always assuming your rim, spokes and hub shell are in excellent condition. If the wheel is missing spokes, or if the some spokes are severely bent or gouged, this is the time to replace the broken or bad spokes.
Without the sprocket in the way, installing new spokes is relatively easy. After removal of the tire, tube and rim strip, the wheel can be brought to a competent bike shop that can measure the existing spokes and sell correctly sized replacements including new nipples.
When I replace spokes, I do them one at a time, following the path of the spoke I just pulled out. Wheels are typically "cross spoked", meaning each spoke goes under two and then above one, or vice versa. On four cross wheels it's under three and over one, or vice versa. Cross spoking makes the wheel more ridgid, which is a good thing for both speed and manuverability. I always put a little grease on the spoke threads, the part of the nipple that sits on the rim, and the spoke head.
The grease on the threads and the nipple make it easier to turn the nipple and true the wheel. The grease on the head of the spoke, in my opinion, lessens wear, stress and corrosion, giving the spoke a longer life. Once again, remember that if spokes cost 75 cents apiece, and you need to replace 15 of them, a new wheel might be more economical.
I was surprised, but gasoline being what it is remember, my bike was out of commission , I didn't want to drive to a different bike shop to save a couple bucks. Before final reassembly, I always make sure to put it together dry, without any grease.
This gives me several advantages:. When reassembling anything, I often screw it up the first, second or even third time. By reassembling several times, I understand how it works, plus I can try it out. When I reassemble the wheel without grease, I can turn the sprocket forward and verify that the wheel turns.
I can turn the sprocket backwards and verify that the wheel quickly stops. I found that I can dry assemble and unassemble the hub in about 7 minutes. That means I can do it three times in 21 minutes. That 21 minutes is time well spent, because when I put it together with grease, I do it correctly the first time. Performing a trial assembly with grease would be a messy affair to say the least. Dry assembling it is neat and clean.
My bicycle repair philosophy is usually "there's no such thing as too much grease". After all, I can always wipe off the excess after assembly.
This philosophy is NOT appropriate for coaster brakes. Because the brake pads ride so close to the hub wall, excessive grease between the clutch and brake pads could actually push the brakepads lightly into the hub, creating drag. Excessive grease between the brake pads and hub wall could also create drag, and could also decrease braking effectiveness. Putting the wheel together dry gives an opportunitye to see how it operates without grease. If there's excessive friction after final assembly with grease, and the cones are not overly tight, then the grease is slowing the wheel.
Dry assembly yields a baseline to diagnose problems caused by excessive grease. I use voluminous grease on bearing surfaces. I don't want these running dry. I use a VERY light coat of grease on the outer side of the brakepads -- just enough so that the brakepads don't quickly cut up the interior of the hub.
I use a light to moderate amount of grease between the clutch and brakepads, so that it won't run dry and cause notches to be worn in the slanted sliding surfaces.
Here's the reassembly method I use:. Now that the hub has been adjusted for minimal play, the wheel can be accurately trued. This involves first loosening spokes on the side the rim should move away from, and tightening them on the side the rim should move toward. Spokes are loosened and tightened by twisting the spoke nipples.
This can be done with a spoke wrench, or in a pinch, a very carefully adjusted adjustable wrench. The wheel should be spun, and the part exhibiting the most sideways displacement identified, and then the spokes around that part should be adjusted. Then the wheel is spun again, and the procedure repeated.
One should never try to adjust more than one part of a wheel at a time -- that will lead to an ever more egg-shaped wheel in the hands of all but the most competent wheel truers.
Wheel truing is one of the hardest tasks in bicycle maintenance. Few can do it well, and even amongst those who do it well there's a spectrum. Wheelmakers can true a wheel to the point where wobble cannot be perceived with the human eye. Without knowledge of wheel truing, the best move is to pay a bike shop to true it. Those wanting to learn to true wheels, can learn the skill by practice on old discarded wheels pulled out of dumpsters. A detailed treatise of wheel building and truing is beyond the scope of this document.
Obviously the wheel must be reinstalled before the bike can be driven. If the tire, tube and rimstrip were removed, they should be reinstalled. Most tires are intended to roll in a certain direction, so care must be taken that they're installed in the proper "polarity". Care must be taken in inflating the tire that there is not a blowout. As the tire is slowly inflated I do it with a gauge equipped hand pump , the tire should be checked to make sure no part is starting to "come out" of the rim.
I often underinflate the tire by about 5 to 10 PSI, and then after my first ride I pump it up to the correct pressure. The correct pressure might be less than the max pressure printed on the tire, but should never be more if you want to minimize the chance of blowouts and the crashes they create. The torque arm must be fastened to the chain-stay via a coaster strap and a safety screw that won't come loose.
The nuts on both sides must be very tight so a quick and heavy push of the type used to out-accelerate a bus won't pull it loose. The chain tension must be adjusted to account for the eccentricity of the front chainwheel. No part of the revolution should tighten the chain so much that there's absolutely no slack, but there should be no extra slack, to prevent the chain coming off.
On a coaster brake bike with no front hand brake I recommend installing a front hand brake as a "plan B" , a thrown chain means no brakes and disaster.
The chain tension must be gotten right, and it must be checked often. After any bike repair I test thoroughly and vigorously. If the repair was inadequate, I want it to fail in controlled conditions, not when I'm racing through the intersection of and In the case of a coaster brake bike, I repeatedly perform controlled stops, and then perform one skidding stop.
I ride for several minutes. Then I go on a hill in a lightly trafficked area and brake there. I also test for easy rolling. I've named many of my bicycles. My current one speed is named " Always Ready ". With no derailleur worries, and minimal handbrake worries the front can be adjusted fairly loose, after all, it's just a "plan B" , life is easy. My wheels needn't be all that true. Even a serious wheel pretzelling experience on a ride doesn't prevent my return home.
Always Ready certainly isn't the fastest bike I've ever had -- I'd need to spin rpm to go 20 miles per hour, and over to go 25 miles an hour. It has 46 teeth in front, 18 teeth in back, and 26" tires. But for average riding around the city, if I'm not in a hurry, it's pretty good. And it works every time. Start by flipping your bike upside down so the handlebars and seat rest firmly on a flat surface.
This will stabilize your bike so you can freely work on the rear wheel hub. If you have a friend or family member around, you can ask them to hold the bike as well. Be careful not to tip your beach cruiser over. Detach the metal band that attaches the coaster brake reaction arm to your frame using a screwdriver to remove the bolt. Next, loosen the axle nuts on both sides of the wheel that secure it to the bike frame. You will want to use your adjustable wrench to do this. Once the wheel becomes loose, you can then disengage the chain from the hub sprocket.
Now that the chain is disengaged, you can remove the wheel from the bike frame. How do you tighten a coaster brake hub?
You can easily tighten the coaster brake cones using cone wrenches. You want to make sure it is tight but not too tight. If the coaster brake cones are tightened too much the wheel will not rotate properly. If the cones remain too loose, the wheel will continue to wobble. The metal band has multiple holes to fit different-size chainstays. Cinch it tightly around the chainstay -- John Allen].
The attachment of the reaction arm to the chainstay is vitally important. One of the most common causes of coaster-brake malfunction is failure to properly secure the reaction arm after removing and re-installing the wheel. If the bike is ridden without the reaction arm properly secured, the arm will rotate downward, effectively loosening the left cone. The result will be a shaky wheel, and an increase in the amount of reverse pedal travel required to activate the brake.
As the disengaged reaction arm and left cone turn, they screw the left cone outward. This squeezes the forkend hard against the left axle nut. As a result, if you try to unscrew the left axle nut, you may find it impossible to turn because of the pressure of the cone.
Bike shops frequently see bikes come in where the left axle nuts have been butchered by unsuccessful attempts to loosen them.
The trick is to treat the cause, not the symptom. Instead of immediately going for the axle nut, use a hammer to rotate the reaction arm back to its proper position. This will often bring everything back to proper adjustment with a minimum of trouble. At the very least, it will ease the binding of the axle nut, and allow you to adjust the bearing cones in the normal manner. Single-speed coaster brakes are pretty simple.
To disassemble a coaster-brake hub, all you need to do is to unscrew everything from one end of the axle or the other. All of the parts will then come out of the left side of the hub shell. Two-speed coaster-brake hubs may shift by means of a "kickback" mechanism which shifts when backpedaling, or automatically by means of centrifugal weights. The brake mechanism of multi-speed coaster-brake hubs is similar to that of single-speed coaster brakes, but these hubs can be quite complicated.
Links to parts lists and rebuilding information for almost every coaster-brake model are at the bottom of this page. When the sprocket turns forward, normal pedaling, the driver's threads pull it to the right, where the conical projection on the right end of the brake cone jams into the narrow part of the hub shell, transferring the pedaling force to the hub shell, and thence to the rest of the wheel. Sometimes a retarder spring can be tightened by bending, sometimes it just needs to be replaced, if you can find one.
Single-speed coaster brakes are intended to be pretty much packed with grease. There is no part of a coaster brake that can be harmed by grease, so be generous in applying it. You should use a grease with tolerance for high temperatures, such as automotive brake grease, but even so, coaster brakes used in mountainous terrain can "cook" any common grease. An internal-gear hub with a coaster brake may need more than one type of lubricant. Follow manufacturer's recommendations. The left cone is attached to the reaction arm the arm that runs below the left chainstay, and is secured to the chainstay by a clamp of some sort.
If you loosen both axle nuts, and stick a cone wrench onto the right side cone, or its locknut, you can turn the whole axle. Since the left cone is immobilized by the reaction arm, turning the axle will adjust the cone. Loose axle nuts could wobble off while riding and you could lose your back wheel. Christina Shepherd McGuire writes articles about adventure sports, fashion, mothering and natural living.
McGuire holds a Bachelor of Arts in English literature. By: Christina Shepherd McGuire. Published: 06 September, More Articles.
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