You may be able to get greater leverage by standing behind the wheel and leaning over the top as you push down on the chain whip.
7. Remove the smallest cog after it’s loose.
The others will slide off.
Removing individual the cogs on a freewheel or cassette
Occasionally, you may decide to replace an individual cog because of wear or because you want to change its size. After you’ve removed your freewheel or cassette, you can follow these steps to remove individuals cogs:
1. Secure the freewheel or cassette in a vise (as shown in Figure 11-7).
2. Wrap the chain of a chain whip around the smallest cog.
3. Turn the chain whip in a counterclockwise direction to remove the cog (as shown in Figure 11-8).
Figure 11-7: Preparing to remove individual freewheels.
Figure 11-8: Removing a cog from a freewheel.
If you don’t have a vise, you can use two chain whips together:
1. Wrap the chains of the chain whip around two adjacent cogs such that the handles of the tools cross.
You’ll have more leverage if you keep the handles close together.
2. Squeeze together the two chain whips until you loosen the cogs.
This procedure is shown in Figure 11-9.
Whichever method you choose, as you remove the cogs keep track of any spacers (see Figure 11-10) between them. You’ll want to put these back in place in the proper order when your reinstall the freewheel.
Figure 11-9: Using a pair of chain whips to loosen the cogs.
Removing the free-hub body
If the free-hub body’s ratcheting mechanism gives out or if it’s making noise, you may have to replace it or remove it for lubrication if you have a model that allows for this.
To remove the freehub body, follow these steps:
1. Remove the rear wheel from the bike (see Chapter 7).
2. Remove the cassette from the free hub (see “Removing a cassette,” earlier in this chapter).
3. Remove the lock nut and cone from the other side of wheel and pull the axle through.
4. Remove the hub bearings.
Replace them if necessary.
5. Use the proper size Allen wrench to unscrew the bolt in the center of the free-hub body and remove the free-hub body.
6. Clean the body with a degreaser, apply oil, wipe off any excess lubrication, and reassemble using the reverse of this procedure.
Figure 11-10: Keep track of spacers between the cogs.
Installing a Freewheel or Cassette
To install a freewheel, follow these steps:
1. Apply grease to the threads on the inside of the freewheel and to those on the hub.
2. Thread the freewheel in a clockwise direction, being careful to make sure that the threads align properly.
3. Thread the freewheel by hand until it begins to tighten.
You can use a chain whip to tighten the freewheel further, although this usually isn’t necessary because riding the bike will tighten it.
To install a cassette, following these steps:
1. Slide the cassette onto the body of the free hub.
Find the one spline on the freehub that is wider than the others, and align it with the same wide spline on the inside of the cassette.
2. Slide any smaller individual cogs onto the hub.
If there are spacers be sure to include them in the proper position.
3. Grease the threads of the lockring and screw it into place on the hub.
4. Attach the freewheel remover to the center of the cassette.
5. Insert the quick-release skewer into the center of the hub, and tighten the nut to hold it in place.
6. Using an adjustable wrench, turn the freewheel remover in a clockwise direction to tighten.
After you hand-tighten the lockring, you only need to tighten the lockring about five to ten clicks with the tool. Do not overtighten.
Part III
Shifting into a Higher Gear: Advanced Bike Repairs
In this part …
If you’re planning on overhauling your bike, replacing some of its components, or performing major repairs, this part is for you. Here we focus on several “systems,” including the frame and suspension, the drivetrain, the steering system, and the shifting system. Although these procedures are more advanced than those in Part II, with this book by your side, you can do these yourself as long as you have the right tools — and patience. After you tackle the repairs in these chapters, you’ll be chatting up your local bike-shop mechanic, watching the Tour de France with a new appreciation, and impressing your friends with your mastery of bike repair and maintenance.
Chapter 12
Holding It All Together: The Frame and Suspension
In This Chapter
Understanding how your frame is built
Knowing what to look for in a frame
Inspecting a frame for problems
Identifying the different types of suspension
Adjusting and maintaining your suspension
For all the focus given to other parts of the bike when it comes to improving comfort and bike handling, the frame is given surprisingly little attention, especially considering how important it is to your bike. The frame dramatically impacts the personality of your bike — its stability, how it handles corners, whether it can carry loads, and how aerodynamic it is. It also determines your position on the bike in relation to the pedals, the seat, and the handlebars. Slight changes in this position can greatly impact the way a bike rides.
In this chapter, we take a closer look at the frame and how it impacts the biking experience. We discuss how frames are designed and constructed and what qualities you should look for when shopping for a new frame. We also provide advice for inspecting and maintaining your frame.
We also discuss bike suspension in this chapter. The suspension acts as an extension of the frame by being an intermediary between the road and the bike to absorb the bumps and jars so your frame and body won’t have to. Suspension is found on more and more bikes these days, so understanding how suspension works and the steps to adjust and care for it is a good idea — if your current bike doesn’t have suspension, your next one just might.
I’ve Been Framed: Your Bike’s Frame
Although there are a number of different frame designs, some more strange than others, the diamond shape is most popular. In this design, there is a main triangle that includes the following:
Head tube: The head tube is where the fork connects with the frame and where the headset sits to enable steering.
Top tube: The top tube connects the seat tube with the head tube and can be horizontal or angled up or down, depending on the style of the bike. Cables are frequently run along the top tube.
Down tube: The down tube connects the head tube with the bottom bracket. This is where your water-bottle cage usually goes. On older bikes, this was the location for the friction shifters.
Seat tube: The seat tube is what supports your butt by holding the seat post and saddle in place. It’s often used for attaching water-bottle cages and bike pumps.
Bottom-bracket shell: This is a short, fat tube that holds the bottom bracket. It runs sideways across the bottom of the bike and is usually threaded.
There also is a rear triangle, which consists of the seat tube, along with the following:
Chain stays: Chain stays run parallel to the bike chain and connect the bottom bracket to the rear dropouts. On some bikes, cables are routed along the chain stays.
Seat stays: The seat stays connect the seat tube with the rear dropouts. They’re often used for mounting brakes, fenders, or bike racks.
The final section of the frame is the fork and steerer tube. The fork is how the front wheel connects to the bike. It consists of two legs with a dropout each for the wheel and a steerer tube, which inserts into the head tube.
A number of factors in the geometry of a frame affect how the bike handles:
Seat-tube angle: The seat-tube angle is based on the angle of the seat tube in relation to the ground. This angle determines how your weight is distributed between the saddle and the handlebars. A steeper seat tube creates a more aerodynamic position with more of your weight shifted forward to the handlebars. With a shallower seat tube, the saddle is positioned farther behind the bottom bracket and your weight is directed toward the back of the bike.
The angle of the seat tube also impacts how you pedal, because it changes your position in relation to the bottom bracket, where all the pedaling takes place. A steeper seat-tube position provides a more direct transfer of power from your legs and is better for higher-cadence pedaling. A shallower seat tube is better for slower pedaling, such as climbing while seated.
Head-tube angle: The head-tube angle impacts your bike’s handling. A steeper head tube will provide more responsive steering, whereas a more shallow tube will give you more relaxed steering. If you use your bike on mountain trails and need quick, responsive turning to avoid hitting objects, a steeper head tube is for you. On the other hand, if your riding consists of taking two-week tours where you’re on long stretches of road for hours at a time, a more shallow seat tube is probably the way to go.
Chain-stay length: Chain-stay length also impacts a bike’s handling. A shorter chain stay brings the wheel closer to the bottom bracket and makes the bike’s handling more responsive. For racing and performance, a shorter chain stay won’t allow the frame to flex as much, so more of your pedaling energy is transferred to the rear wheel. In addition, because more of your body is above the rear wheel, traction is improved, which is useful on mountain bikes.
A longer chain stay flexes more and provides a larger wheel base, which improves stability and comfort. Longer chain stays are found on many touring bike frames, where stability for a loaded bike is important. Having the wheel farther back also helps keep your foot from hitting the pannier bags.
Bottom-bracket drop: The bottom-bracket drop is how far the bottom bracket sits below an imaginary horizontal line drawn between the front and rear dropouts. Most mountain bikes have less of a bottom-bracket drop because they need the extra clearance to avoid the obstacles found on trails. Racing bikes also are designed with less of a bottom-bracket drop to prevent the pedals from hitting the road in tight corners. An increased bottom-bracket drop extends the wheelbase and lowers the bike’s center of gravity, both of which improve stability. As you may expect, a lower bottom-bracket drop is found on touring bikes where stability is valued.
So how do all these frame options come together to form the bike that’s perfect for you? For the average rider, bike frames designed with comfort and stability in mind are probably going to be the best choice. Frames with slightly longer chain stays, lower bottom-bracket drops, and more relaxed seat-tube and head-tube angles provide this. For mountain bikes and more expensive road bikes, the tendency will be for more responsive and stiffer rides with frames that have shorter chain stays, higher bottom-bracket drops, and steeper seat-tube and head-tube angles.
Figure 12-1 illustrates a mountain bike frame and Figure 12-2 shows a road-bike frame. See if you can notice some of the differences between the two frames: The mountain bike has a shorter chain stay, a higher bottom bracket, and steeper seat tube and head tubes than the road bike.
Figure 12-1: A mountain-bike frame.
Figure 12-2: A road-bike frame.
What to look for in a frame
Frame materials are often compared based on the qualities of strength, stiffness, and weight:
Strength: Strength refers to the durability of the frame. If you crashed, a stronger frame would be more likely to survive the crash intact. For a mountain bike that’s going to be put through some challenging trail rides, strength is important.
Stiffness: Stiffness describes how much the frame material flexes under a force. For example, when you pedal, you’re applying a force to the frame; around the bottom bracket, it’ll flex slightly depending on the frame material.
Weight: Weight is an important factor with frame materials. In an ideal world, you’d have the lightest frame possible so on your next climb it wouldn’t feel like you were hauling a sack of potatoes with you. Of course, lighter frames require more expensive materials, which makes them cost prohibitive for some riders.
Types of frame materials
The most common frame materials are
Steel: Steel frames have been around for a long time, and the best of them can still compete with some of today’s frames fashioned from fancier materials. The higher-end steels or steel/alloy blends (such as chrome-moly) are very strong, offer significant stiffness, and are long lasting, all for decent prices. Cheaper, mild steels or high-tensile steel are found on lower-end bikes where the frames are thick and heavy.
The downside to steel, other than the weight, is that it can rust. Also, high-tensile or mild steel is very uncomfortable — all the road vibrations are transferred through the frame to your butt. The better-quality chrome-moly frames with butted tubing are much more comfortable than the mild steel.
Aluminum: Aluminum has become the most popular choice for manufacturers of bike frames. It’s lighter than steel, has better stiffness, and, unlike steel, it doesn’t rust. The other benefit of aluminum is that it can be easily formed into different shapes to improve the performance and aerodynamics of the frame. The downside of aluminum is that it’s not as strong as steel, so a big-time crash could leave your frame mangled beyond repair. The other factor with aluminum is that it fatigues over time, increasing the chances that the frame could break. Aluminum also transmits road vibration far more severely then steel or carbon fiber.
Carbon fiber: Carbon-fiber frames are made by gluing, with an epoxy resin, individual carbon-fiber sheets together in patterns that enhance its strength. Manufacturers use this technique to customize frame strength by adding layers of fibers to the parts of the frame that require greater strength, and removing layers of fibers from the parts of the frame that doesn’t need as much strength.
The fact that carbon is strong and light makes it a desirable material for frames. However, carbon fiber is expensive. Carbon-fiber frames offer the most comfortable ride with the most efficient use of energy. The other nice thing about carbon fiber is that the frame can be made in almost any shape or size. Manufacturers aren’t limited to the standard tube sizes or the typical rounded shape of a frame tube.
Titanium: Titanium, like carbon, is on every serious biker’s wish list when it comes to frame materials. Titanium is light, it doesn’t rust, and it’s as strong as most steels. It’s less stiff than steel and flexes to give a comfortable ride. Unfortunately, titanium is very expensive and out of reach for most bikers.
Inspecting your frame
Even though the frame may appear to be one solid, immovable object, it’s not unheard of for them to go out of alignment occasionally. Any kind of impact — whether it’s an accident, your bike falling over, or jumping your bike over a curb — could impact the alignment.
To inspect your frame for issues, follow these steps:
1. Stand in front of your bike and peer down the center of the frame (as shown in Figure 12-3).
You should see the head tube line up with the seat tube.
2. Facing forward, straddle your bike with both legs and look down at the frame (as shown in Figure 12-4).
You should see the top tube line up with the down tube. The front forks should also be equidistant apart from each side of the wheel.
3. Stand behind the bike and check that the seat tube lines up with the head tube (see Figure 12-5). Look down at the seat stays and make sure they are parallel.
Figure 12-3: Checking the frame from the front.
Figure 12-4: Checking the frame from the top.
Figure 12-5: Checking the frame from the back.
4. Visually inspect the frame for defects (as shown in Figure 12-6).
Pay particular attention to where the frame is welded together.
For hard-to-see places, close your eyes and run your fingers along the side of the tube. (Closing your eyes allows you to actually feel and not have your eyes trick your brain.) If you see or feel bubbles, ripples, or cracks in the paint, it could be a sign that your frame has issues. Take it to your local bike shop for further inspection.
5. Tie a string to the rear dropout on one side, and run it toward the front of the bicycle head tube and then back to the dropout on the other side and tie it.
Measure the distance from the string to the seat tube on each side. If the measurement’s are not exactly the same, your frame is bent and out of alignment.
If you think your bike is out of alignment, take it to your local bike shop. Many shops have tools that can check the alignment and straighten the frame as needed. If your frame is made of steel, repairing it is usually much easier than if you have an aluminum, carbon, or titanium frame. If your frame is not made of steel, your best bet might be to turn to your bike’s warranty.
Figure 12-6: Checking the frame for defects.
Maintaining your frame
In general, the frame is one of the lowest-maintenance parts of your bike. Nevertheless, you shouldn’t ignore it when you care for your bike — there are a number of things you can do to make sure it lasts as long as the manufacturer intended. We cover these basic maintenance tasks in this section.
Preventing rust
For steel frames, rust is the number-one enemy. Water from rain, sweat, or muddy conditions can work itself into the frame and start corroding it. To minimize the chances of this happening, spray an anti-rust product, such as WD-40, into the frame every opportunity you have.
Bike Repair & Maintenance For Dummies® Page 17
