Bike Repair & Maintenance For Dummies®

by Dennis Bailey

  If you’re really serious about protecting your frame, you can try one of a number of rust-inhibitor products (such as J. P. Weigle’s Frame Saver, available at bike shops). When you spray a rust inhibitor inside a frame, it forms a barrier that protects against rust.

  Painting your frame

  Keeping your frame painted can go a long way toward preventing rust. Small chips in the frame’s paint may allow rust to take root in your frame and spread. If you have time on your hands during the winter months, give your bike a fresh coat of paint as part of its annual overhaul. At the very least, touch up any small chips in the paint so that they don’t become sources of rust. If rust has already appeared, use a fine-grain sandpaper to remove the rust before painting.

  Most bicycle manufacturers don’t make touch-up paint available, so use a similar color automotive touch-up paint from an auto dealer or auto parts store.

  Try to keep paint chips to a minimum:

  Use chainstay protectors to protect your chainstay against impact from the chain.

  Use O-rings on cables to keep them from rubbing against the frame’s surface.

  Where cables come in contact with the frame, place a small piece of tape between the cable and the frame, to protect the frame’s surface.

  Butt out! Frame butting

  When it comes to crafting bike frames, manufacturers have more tricks up their sleeves than just changing the frame material. Engineers have come up with a variety of ways to manipulate strength and rigidity of frames, including changing the tube width, the thickness of tube walls, and the tube shape.

  Butting is one such technique. It’s the process of making one part of a tube thicker than another part of the same tube. This is usually done on the inside walls of the tube, so the outside — the part that you see — is all the same. The thicker part of the tube provides strength where it’s needed more, and the thinner part of the tube helps reduce weight. Single-butted tubes have one side of the tube that’s thicker than the other. They’re often found on seat tubes where the thicker part of the tube is attached to the bottom bracket to provide support against the force of pedaling. Double-butted tubing is thin in the middle, where less strength is needed, and thicker on both ends, where the tube connects to other tubes. On some frames, manufacturers may even use triple- or quadruple-butted tubes.

  Waxing your frame

  Waxing is not only a great way to keep your bike looking shiny and new, it’s effective at keeping rust at bay. Give your bike a thorough waxing as a part of your annual overhaul, when the frame will be more accessible. If you ride a lot, think about waxing the frame every few months.

  Although there are a number of waxes designed for bikes, any all-purpose car wax should do the trick.

  Suspended in Disbelief: The Suspension

  In the continuing trend toward bikes offering a more comfortable ride, suspension has played a leading role. Riding a bike without suspension on a rough road makes you feel like you’re the shock absorber. Every road or trail shock that hits a stiff rigid bike is transferred directly into your arms, legs, and the rest of your body. Not only that, but if you hit something on the road or trail with enough force, the bike may stop suddenly and send you flying like Superman.

  On a bike with suspension, when you hit a pothole or run over a rock, the shock absorber dissipates the force before it’s absorbed by your bike and body. It improves safety, comfort, and riding efficiency (because you won’t have to hover over your seat to act as your own personal shock absorber). Bicycles with suspension are safer because they give you more control of the bicycle — the wheels stay in contact with the ground more and you don’t get bounced around on the trail as much.

  The main idea behind suspension is that the coiling of a spring keeps you floating or suspended when you ride. This provides the bounciness or springiness of the suspension. The second idea is that the bounciness of the spring is better suited for a bike if it can be controlled or dampened. A spring with too much bounce will make you feel as though your bike is attached to a pogo stick.

  Suspension is generally found on four places on a bike:

  Fork

  Stem

  Seat post

  Rear axle

  Types of suspension

  Most suspension systems use some type of spring to absorb impacts from the road. Generally, three types of springs are used:

  Coil: Coil springs are made from steel of different gauges and are the most popular type of spring.

  Air: Air maintained inside a sealed chamber acts as another kind of spring.

  Elastomer: Elastomers are made of urethane and aren’t as common these days as they were in the past.

  Suspension works best when a spring is paired with some kind of damping system. Damping is the ability to slow the rebound of the suspension. Rebound is the speed at which the suspension returns to its original position after it has been compressed. And compression is the amount of time it takes for the suspension to absorb your weight. If your suspension has unchecked rebound, you’ll feel like you’re riding a bouncing ball. If your suspension has the bouncing-ball feeling, adjusting the damping can reduce the speed at which the suspension compresses and rebounds.

  Air and oil are two types of damping systems. In an air-based damping system, air pressure is adjusted to change the amount of damping. In oil-based damping systems, a piston flows through a volume of oil. Adjusting the size of the hole in the piston changes the amount of damping.

  Many suspension systems have adjusters that allow you to change the amount of damping and preload (the amount of compression applied to suspension before it supports any weight). By preloading the suspension, it will sag less and give you a stiffer ride. Reducing the preload will cause the suspension to sag more. On many suspension forks, the preload adjuster is found on the top of the fork and the damping adjustment at the bottom of the fork.

  Tuning the suspension

  Although there are a number of ways to tune suspension, we’ll focus on one of the most basic adjustments — controlling the amount of sag (the amount of movement in the suspension when you’re sitting on your saddle). The amount of recommended sag for most bikes is normally around 25 percent.

  You can adjust the suspension much easier if you have a friend around to assist you.

  To adjust the rear suspension sag, follow these steps:

  1. For a coiled-spring-covered shock, determine the amount of travel (the total range that the suspension can move) by measuring the length of the coil when it’s fully extended, without any weight on the bike.

  Suspension on the front forks usually has a greater travel than the rear suspension. Too much travel is not a good thing — it can damage your suspension by causing it to bottom out.

  2. Sit on you bike while it’s stationary and don’t touch the ground with your feet.

  Have your friend support you if needed.

  3. Measure the length of the coil to determine the amount of sag.

  4. Divide the measurement from Step 3 by the measurement from Step 1, to determine the percentage of sag.

  For example, if the amount of travel was 4 inches and your sag was 1 inch, the percentage of sag is 1 ÷ 4 = 0.25, or 25 percent.

  If your sag is less than 25 percent, the suspension is too stiff. Proceed to Step 5.

  If your sag is more than 30 percent, the suspension is too soft. Proceed to Step 6.

  5. Adjust the spring tension in front by rotating the spring seat (as shown in Figure 12-7). To reduce tension and increase sag, turn the knob counterclockwise one turn.

  Repeat steps 2 through 4 until the sag is between 25 percent and 30 percent.

  6. Adjust the spring tension in front by rotating the spring seat (refer to Figure 12-7). To increase tension and reduce sag, turn the spring seat clockwise one turn.

  Repeat steps 2 through 4 until the sag is between 25 percent and 30 percent.

  Figure 12-7: Adjusting rear suspension.

  To adjust the front suspensi
on sag, follow these steps:

  1. Determine the total amount of travel by measuring from the top part of your forks to the seal of the forks or the lowest part of the shock that moves relative to the rest of the bike.

  2. Sit on you bike while it’s stationary and don’t touch the ground with your feet.

  Have your friend support you if needed.

  3. Measure the distance between the two points again to determine the amount of sag.

  4. Divide the measurement from Step 3 by the measurement from Step 1, to determine the percentage of sag.

  For example, if the amount of travel was 4 inches and your sag was 1 inch, the percentage of sag is 1 ÷ 4 = 0.25, or 25 percent.

  If the sag was less than 25 percent, the forks are too stiff. Proceed to Step 5.

  If the sage was more than 30 percent, the forks are too soft. Proceed to Step 6.

  5. Adjust the spring tension in front by rotating your screw knob on the top of your fork (as shown in Figure 12-8). To reduce tension and increase sag, turn the knob counterclockwise one turn.

  Repeat steps 2 through 4 until the sag is between 25 percent and 30 percent.

  6. Adjust the spring tension in front by rotating your screw knob on the top of your fork (refer to Figure 12-8). To increase tension and reduce sag, turn the knob clockwise one turn.

  Repeat steps 2 through 4 until the sag is between 25 percent and 30 percent.

  If your friends have deserted you for the day, do the same process except use a zip tie around the fork instead of just eyeballing or measuring by hand. Use it to get the total travel and then reset it to get the sag. This gives you a more accurate measurement and is easier to perform.

  Figure 12-8: Adjusting the front suspension

  Maintaining the suspension

  How to maintain a bike’s suspension varies depending on the type of suspension. Suspension systems that use oil need more attention and maintenance than those that used coil-based springs. Follow your bike’s owner’s manual for how to maintain the suspension properly.

  One of the most important things you can do for your suspension is to keep it clean. Disassemble your forks regularly and according to the recommended timeframe in the owner’s manual. (Figure 12-9 shows a disassembled suspension fork.) As a part of your annual overhaul, you’ll want to disassemble the forks and replace seals, wipers, and bushings.

  Also, regularly inspect your bike’s suspension for signs of oil leaks. If you notice a leak, you should replace the seals as soon as possible.

  Figure 12-9: A dis-assembled suspension fork.

  Chapter 13

  Putting the Pedal to the Metal: The Drivetrain

  In This Chapter

  Working on pedals

  Removing and installing crank arms

  Dealing with chainrings

  Handling the bottom bracket

  The drivetrain is sort of like your bike’s transmission. It converts energy from your legs into mechanical force to power you forward. The drivetrain starts with pedals attached to the bike’s crank arms, which are mounted to the frame by the bottom bracket. Moving the pedals begins a process that drives your energy through the chain to the back wheel, moving the bicycle forward down the trail. In this chapter, we explain how to remove, install, and overhaul each of the components that make up the drivetrain.

  Working on the drivetrain is not overly complicated, but it does require some special tools, including special wrenches, bottom bracket tools, crank-arm extractors, and so on. If you’re committed to a long-term relationship with your bike and want to do your own repair and maintenance, purchasing these tools will be a good investment. Otherwise, when it comes time to overhaul these parts, you can always take your bike to your local bike shop and let the experts there handle the job.

  Putting the Pedal to the Metal

  The pedals are an important link in the transfer of power from your legs to your bike. However, if you were buying a new bike, you wouldn’t get that impression because manufacturers sometimes install the cheapest, most low-end pedals possible.

  Dennis recently bought a new road bike for his wife. To look at it was to admire a work of art … except for the ugly, thick, rubber pedals attached to the cranks, which looked as if they were taken from a child’s bike.

  Manufacturers use cheap pedals because many bicyclists develop personal preferences for certain types of pedals and, when they buy a new bicycle, they have their old pedals mounted on their new bikes — or buy a new set of pedals.

  In this section, we show you what to look for in new pedals and tell you how to keep your pedals working well.

  Shopping for new pedals

  There are many different pedal styles on the market. The traditional style pedals are flat. Other styles have binding systems that allow you to strap your foot to the pedal with a toe clip and strap or lock your shoe into the pedal with a clipless pedal.

  Many casual riders think that having their feet attached to the pedal would be uncomfortable or worry that disengaging their feet would be difficult. On the contrary, toe clips or clipless pedals are easy to manage, and they offer significant gains in performance.

  On most pedals, you can attach a toe clip and strap, which helps prevent your foot from slipping off the pedal and keeps the ball of your foot centered over the pedal, which improves the efficiency of your pedaling. Toe clips include a buckle that allows you to adjust the strap so that it can fit a variety of shoe types and sizes. Because you can wear any type of shoe with them, these are especially nice if you’re a casual rider and like to get off your bike occasionally and sightsee or just walk around.

  Another option is to go with clipless pedals, which are similar to ski bindings. They’re designed to grab a cleat built into the bottom of specially designed biking shoes. These pedals hold your foot in place while you pedal, greatly increasing your pedaling efficiency. Snapping your shoe into the pedal is a breeze, and unlocking the cleat and removing your shoe from the pedal is a quick, natural movement with an outward twist of your heel.

  There are a number of different clipless systems on the market each with a slightly different method for locking the cleat into the pedal. If you’re buying biking shoes, make sure you check them for their compatibility with your pedals, and vice versa.

  If you’re worried about whether you’ll be able to unlock the cleat from the pedal quickly enough in an emergency, don’t be. We can pull our shoes off the pedals faster with clipless pedals than we can with toe clips. Plus, clipless pedals are usually designed with a tension adjustment — usually a small bolt that’s turned clockwise to increase tension and counterclockwise to reduce tension. If you find that the cleat in your shoe is a little difficult to remove, try adjusting the tension. Practice getting in and out of your clipless pedals a few times before you ride so that you don’t come to your first stop and fall over with your shoes locked into your pedals.

  If you opt for clipless pedals, you’ll want to adjust them to the pedaling position that is most natural for you. Many shoes allow you to move the position of the cleat. In addition, some pedal systems provide for some movement or float after the cleat locks into the pedal — this gives your feet some ability to move on the pedal, which reduces tension and stress on the knees and keeps you from staying in one position during your ride.

  Talk to the staff in your local bike shop to find the right adjustment for your pedaling system. This will help ensure that you don’t end up locking your shoes into pedals in a position that’s unnatural for your body and puts strain on your legs when you bike.

  Identifying worn-out pedals

  Pedals are often subject to a lot of abuse. Not only do they absorb energy from your body, but they’re low to the ground and away from the center of the bike, which means they’re often exposed to harsher conditions than the rest of the bike.

  If you’re hearing creaking or grating sounds or noticing any general looseness when you rotate the pedals, they may need to be replaced. Be sure to isolate t
he sounds or looseness to the pedals and not the bottom bracket before you start spending money replacing parts.

  Removing pedals

  Pedals can sometimes be difficult to remove. They’re usually torqued pretty well because the pedaling motion gradually tightens the screws. If your pedals haven’t been removed for a while, or if not much grease was applied the last time they were installed, this may make it harder for you to remove them.

  Keep in mind that the threads for the left pedal (the left side as you’re sitting on the bicycle — usually the non-chainring side) is reversed. Both pedals loosen by moving the wrench toward the back of the bike, and both pedals tighten by moving toward the front of the bike. In other words, forward pedal motion tightens, and reverse pedal motion loosens.

  Pedals are designed this way so that when you pedal, the thread doesn’t come loose.

  The best way to remove a pedal is to use a pedal wrench, which allows you to get a firm fit on the wrench flats, as shown in Figure 13-1.

  Follow these steps to remove your pedals:

  1. Spray some penetrating oil into the pedal where the threads are screwed into the cranks.

  Allow the oil to work itself into the threads for a few minutes.

  2. Rotate the crank arms into a three o’clock and nine o’clock position.

  3. Using a pedal wrench, hold the crank arm steady, and unscrew the right pedal from the crank in a counterclockwise direction.

  4. Repeat Step 3, except unscrew the left pedal in a clockwise direction.

  If you have trouble loosening the pedals, here are some tips to try:

  Slide a piece of pipe over the end of the wrench (as shown in Figure 13-2), effectively extending the length of the wrench, which will give you more leverage and increase the amount of force you can apply.