TVS Workshop
No. 795, Srimawo Bandaranayaka Mawatha, Colombo 14, Sri Lanka.
Customer Service Hotline:
0114 346 931
Services
Brakes
Brakes are obviously the part of the bicycle that deserves the most attention. There are several different types:
U brakes, named for their shape, are used on racing and most other road bicycles. There are various variants like centerpull brakes (Campagnolo Delta, an excellent brake but just too expensive), and sidepull brakes. The smaller they are the better they work because less material means less flex. There are cheap U brakes that would fit around your arm that you can watch bending when you brake. Good brakes are Shimano 105 and up, and any Campagnolo brake. Quick-releases help removing the wheel; Shimano integrates them into the brake and Campagnolo integrates them in the brake lever. You can ride Campagnolo levers with Shimano brakes but vice versa is difficult.
Cantilever brakes are most often used on mountainbikes and hybrids whose tires are too fat to fit an U brake. I do not like cantilevers because they are hard to adjust and require continuous readjustment as the brake pads wear down. They tilt against the rim, which means that unlike U brake pads, cantilever pads do not touch the rim at a constant angle, so the angle must be readjusted frequently. Unfortunately, loosening the one single nut that secures the brake pad makes the whole assembly come loose and you have to adjust some six degrees of freedom all at once. Some people use spacers to adjust the pads while they press the spacers against the rim.
Magura brakes replace cantilevers with two hydraulic cylinders that push the pads straight against the rim. Like regular cantilevers, they need a brake booster, a flat U-shaped piece of steel that connects both brake halves to keep them from pushing the fork apart. Maguras work really well; if they weren’t so expensive I’d vote for throwing out all cantilevers.
There are other forms, such as Shimano V brakes, but I have no experience with them. Hub brakes are often used on cheap bicycles; there are also high-quality hub and disc brakes that are useful for tandems which are much harder to stop. Hub and disc brakes have the disadvantage that they brake the hub, and a lot of force needs to be transmitted to the rim through the spokes.
There are a variety of brake pads that vary in softness. If the rubber compound is too hard, it doesn’t brake well, especially in wet weather; if it is too soft, it wears down too quickly. Since rubber tends to get harder with time, brake pads should be replaced at least every couple of years. I prefer Campagnolo or Aztec. Some brake pads are longer than others, but I have not found this to make a difference. Some brake pads are designed for steel rims, but they don’t make steel rims safe – never use steel rims because they are difficult or impossible to brake in wet weather. Good brake pads are not cheap, but this is about the worst place to save money!
Do not use “safety levers” that extend from the brake levers of cheap road bikes towards the stem (that holds the handlebars in the center). They aren’t safe because they flex and brake poorly.
In road bike shift levers of the kind used for drop (racing) handlebars, the brake cables connect to the inside of the handle and run along the handlebars under the handlebar tape. The older type where the brake cable connects to the upper tip and arc up and then back down to the brakes are dangerous because you can accidentally catch the cable with your gloves, especially if you have aero (triathlon) bars.
For tips on installing and adjusting brake levers, see the chapter on handlebars.
Close
Gear Shift Levers
Again, there are a number of different types:
Down shifters are mounted on the down tube (that connects the front tube with the bottom bracket). They are on their way of becoming obsolete, but are still the cheapest option. They are inconvenient because they require reaching down, which is difficult to do when braking or accelerating hard or riding in difficult situations. A variant that is mounted on the stem is found on very old and cheap bicycles.
Bar-end shifters are mounted at the ends of drop handlebars. I haven’t used them much and find them less convenient than Ergopower and STI brakes because I don’t often keep my hands at the handlebar ends where I can’t reach the brakes. They are popular on touring bicycles.
Campagnolo Ergopower is a system for drop handlebars that integrates the shifting levers with the brake levers. This means you can control everything without moving your hands. There is one lever mounted behind the brake lever that tilts sideways to shift down, and a thumb button on the inner side of the body to shift up. Up to three gears can be shifted down, and any number of of gears can be shifted up with one lever action. The levers become less noisy and hard with time. Both brake and shift cables run along the handlebar under the handlebar tape. This is the system that I prefer. They also come with Campagnolo’s spare parts availability – it’s not going to be a problem to buy and install a replacement spring three years from now, when Shimano won’t even remember what they sold six months ago.
Shimano STI is similar to Ergopower, but there is no thumb button. Up-shifting is done by pushing the brake lever sideways. This is why I prefer Ergopower – it makes me feel more in control because the brake lever doesn’t go in all directions when I hold it with two fingers to be ready to brake. Also, STI has cables connecting to the inside tip of the lever that are not tucked safely out of harm’s way like with Ergopower.
Other types are available for mountainbikes. I have not used them.
On road bikes, the shifter cables run along the down tube, on the left side to the front derailleur and on the right side to the rear derailleur. There is a plastic insert under the bottom bracket that guides the cables. Cables must be bought to match the shifting system used. Ride-on makes special coated cables that run somewhat smoother than regular cables, but don’t really justify the price. Normal cables should be oiled with Teflon oil (which doesn’t gum up with age) before being inserted into the housing.
Shortening the housing is difficult and requires a special tool, or at least a sharp fine metal saw. The housing should be held by a vise. Saw it off very close to the vise grips, then file the sharp edges and smooth out the inner plastic tube. Use metal caps on the ends. Cables are usually too long; cut them with a sharp cutter and either put a cap on the end or solder the end (but don’t use too much solder or they won’t fit through the housing caps). Uncapped unsoldered cables fray.
Close
Chainwheels, Cogs, and Chains
In front, there are either two or three chainwheels. The innermost, smallest chainring is intended for spinning up steep hills. It’s also called “granny gear”, presumably to indicate who would need one. Me, I prefer two chainrings on road bikes because I don’t have to worry about overshifting, because I have to worry less about extreme chain lines, and because I haven’t yet met a mountain that was not easier to climb without a granny gear. The problem with the chainline is that a chain should not run from an inner cog to an outer chainwheel or vice versa.
There are cassettes with eight, nine, or ten cogs on the rear hub (for hub types, see the chapter on wheels). Cassettes with five to seven, and arguable eight, cogs are obsolete. At the time of this writing (2006), nine cogs are still available but fading, and people switch to ten. Ten-cog cassettes require a special narrow chain, and derailleurs and levers may not be compatible, so I recommend going with ten. In most cases, the number of cogs must agree with the type of shift levers; it cannot be upgraded without also replacing the shift lever. Usually cassettes from one vendor cannot be mixed with shift levers from another vendor. There are some exceptions, for example Sachs is said to work with Campagnolo, and Campagnolo sells replacement ratchets to convert levers.
Chains must be the single most neglected part of the typical bicycle. It seems that every other bicycle I see has not been lubricated for years. Unlubricated chains squeak pitifully, make pedaling much harder, and destroy chainwheels and cogs. The problem is that rust and other particles get between the bolts and sleeves of the chain and wear them down, so that the chain gets loose and hence very slightly longer. This means that the distance between two chain links no longer matches the distance between two chainwheel and cog teeth. When this happens only one link connects with a tooth, all others are loose because of the slack. This one tooth takes the entire force and gets worn into a “shark fin” shape. If this shape is pronounced enough, the chain won’t even roll smoothly off the cog or chainwheel; instead the chain will be grabbed by the shark fin.
The insidious part of this is that you don’t notice it until the cogs you use most are already destroyed. Replacing the chain will seem to make matters worse because now all links of the chain get hooked by all the shark fin teeth of the cog simultaneously, which will make the chain skip. This makes the cog unrideable. The only option at this point is to replace all the worn cogs together with the chain.
To prevent this from happening, it is important to lubricate the chain frequently, at least every three weeks or so, more often when riding in wet weather. Before lubricating the chain, it must first be cleaned with an old T-shirt. You can run the chain through the fabric, but it’s really better to clean each link individually. It will only take a few minutes. You should also clean the cogs, chainwheels, and especially both pulleys in the rear derailleur. Then, lubricate the inside liberally, and run the chain through at high speed for some time. Then, wipe off all excess lube. This is important because only the lube inside the chain will do any good, the rest just attracts dirt and increases wear. Ride around the block and wipe off excess lube again.
There is much debate about the best chain lube. You can’t go wrong with synthetic bicycle chain oil, perhaps containing suspended Teflon or other lubricating particles. Don’t use regular (WD-40 or other) machine oil because its viscosity is too low to stay in the chain for very long, and don’t use motor oil because motor oil is designed to work in certain (hot) environments only. Grease doesn’t work too well because it won’t reach the critical parts, you’ll wipe off most of what you apply. This is even more true of wax. Don’t use gasoline to clean your chain, it will remove the factory grease packing of the inner surfaces and you’ll never be able to restore them sufficiently. Chains are not that expensive.
Close
Replacing a Chain
To replace a chain, push a pin out of the old chain and measure the new chain against the old to make sure it has the same number of links. If you have to remove links, remove them at the end without the bolt sticking out. If you have to break a chain with the intent to reinstall it, push one bolt towards the outer side of the bicycle until the link just barely holds together. Bend the chain to disengage the broken link. It’s impossible to re-insert a bolt pushed out all the way. To install a chain, join the chain and push the bolt in until it is flush with the link plate, then push it back from the other side until it’s as flush with the plate on that side as all the other links. Then, bend the chain sideways until it moves freely. A stiff link makes the chain skip when riding. You need a special chaintool for pushing bolts.
The chain length should be chosen so that all gear combinations are possible: if the chain is on the largest chainring and the largest cog, the rear derailleur should still have some play, and if the chain is on the smallest chainwheel and the smallest cog, it should not touch itself near the upper pulley in the rear derailleur. Of course you won’t normally ride these extreme gears because of the poor chainline. If these conditions can’t be met, consider changing the pulleys or chainwheels, or the rear derailleur capacity (i.e. use one with a longer cage). As a rule of thumb, the rear derailleur should be roughly vertical (both its pulleys are exactly below the axle) when the chain is on the largest chainwheel and the smallest cog.
In case of doubt I prefer a shorter chain because this increases its tension and makes it less likely to bounce and hit the chainstays (the frame tubes that connect the bottom bracket and the rear dropouts). On mountainbikes “chain suck” can become a problem when the chain bounces so much that it gets caught between the chainstay and the chainwheels. You can bolt little gizmos to the chainstay to prevent this, but I have seen these gizmos to cause more chainsuck problems than they solve because if the chain gets stuck anyway it gets stuck so tightly that it requires tools to make the bicycle ridable again. I am generally wary of little add-on gadgets.
Close
Workshop
Spare Parts
Auffällig schnell wuchs die gruppe essay schreiben englisch der akademisch gebildeten hohen und mittleren beamten insbesondere im letzten drittel des jahrhunderts