Post by Per Mare Per Terram on Dec 26, 2009 22:15:13 GMT 1
The Bike
There are many different types of bikes on the market e.g. road bikes, mountain bikes (MTB), hybrid bikes (a mix between road and MTB), downhill bikes etc. etc. For now, let’s concentrate on the road bike.
Frame geometry
Road bikes are divided into two main categories: standard frame geometry and compact frame geometry.
Standard frame bikes don’t have a sloping top tube, whereas Compact frame bikes do. In an effort to cut down on frame weight, bike manufactures brought out the compact frame. Less material is used to build a compact frame, hence the reduction in frame weight. However, it is said that, because you need a longer seat post on a compact frame, all gains in frame weight are negated. The debate continues. I don’t feel that the issue regarding the difference in frame stiffness and handling between compact and standard frames are needed here.
Shorter riders are more likely to use compact frame bikes, because of the smaller size of the bike. However, don’t let your bike dealer confuse you with all sorts of promises of gains in performance and climbing ability with a compact frame. Don’t let anyone rush you into a bike.
Frame material
Bikes can be made from all sorts of materials. Let’s discuss the main types:
Steel
Standard steel frames are heavy. Not many manufactures nowadays make steel frames. Steel rusts easily when scratched or damaged.
Aluminium
Probably the most popular frame material. Most entry, intermediate and high end bikes are made from aluminium. Aluminium is lighter than steel, and more corrosion resistant.
Carbon fibre
Because of its strength and lightness, carbon fibre is an excellent choice for a frame material. However, carbon fibre is pricey. Aluminium/carbon is a popular mix.
Titanium
Titanium alloy frames are very light, but very pricey. Titanium is said to have the responsiveness of steel, the shock absorbency of carbon fibre and the stiffness of aluminium. Titanium bike owners call this the “magical ride” quality.
Frame sizes
One of the most important factors to consider before buying a bike is frame size, and is absolutely vital to your safety, comfort, and enjoyment. An ill fitting bicycle is a bad start, and will lead to all sorts of problems in the end. (We’ll discuss the issue of how and what to measure to determine your correct frame size later on)
How are bicycle frames measured?The most commonly used method to determine frame size is by measuring the length of the seat tube (the tube into which the saddle is inserted – see Figure 1). The measurement is made using one of two methods: Centre to Centre (C-C) or Centre to Top (C-T).
Centre to Centre (C-C) is measured from the centre of the bottom bracket to the centre of the top tube.
Centre to Top (C-T) is measured from the centre of the bottom bracket to the top of the top tube.
See Figure 3.
I have no idea why some manufactures use C-T and others use C-C. If someone out there knows for sure, let me know.
The point is that you should make absolutely sure that your local bike shop (LBS from now on) measures you and sells you the right sized frame. If you are serious about buying a bike, then visit a reputable and professional LBS. Don’t buy a bike at a furniture store. Ask the bicycle salesman one question: “Is this bike sized centre-to-centre or centre-to-top?” If the salesman gets a far away look in his eyes, politely end the conversation and find yourself another bike shop.
Some manufactures, like Trek, produce WSD or Woman Specific Design bicycles. Although the method of frame size measurement remains the same for these bikes, they are designed to accommodate the anatomical differences between ladies and gents (ladies normally have longer legs and shorter torsos than men).
Bicycle components
Following is a list of the standard components that come fitted with a complete bike, and a brief description of each.
Groupset
The groupset refers to the gearing and braking components of the bike.
A groupset will consist of the crankset (also called chainrings or chainwheels), bottom bracket, front- and rear derailleur, cassette, chain, front- and rear wheel hubs, gear shifting/brake levers and brake set.
Some of the higher end groupsets will include components such as a seat post, handle bar and stem, head set and pedals.
Crankset (also called chainrings or chainwheels)
Cranksets come in two flavours: double chainring and triple chainring. Chainrings are classed by the number of teeth they have e.g. 53 teeth on the large chainring and 39 teeth on the smaller chainring. Common sizes are 52-39, 53-39, 53-42 and 52-42 for double cranksets and 52-42-30 and 53-39-30 for triple cranksets. You will find that most entry level bikes come with a standard 53-39 crankset.
Bottom Bracket
The axle and bearing assembly around which the crankset revolves.
Front- and rear derailleur (or derailer)
The front derailleur moves the chain from one chainring to another. The rear derailleur moves the chain from one sprocket to another.
Chain
Probably the most neglected component on a bicycle. Modern bicycles use roller chains (the chain is made up of a bunch of small rollers linked together). When replacing a bicycle chain, remember to specify your groupset and groupset speed (e.g. 8 speed) to your LBS.
Wheel hubs
The axle and bearing mechanism around which the wheels revolve. The rear wheel hub incorporates a “freewheel” or "freehub", which allows the wheel to continue turning without needing to pedal (called “freewheeling” or “coasting”).
Cassette
A combination of gears (or sprockets) combined together to form a cluster or cassette. As with chain rings, cassettes are classed by the total number of sprockets installed on the cassette e.g. a 9-speed cassette will have 9 sprockets. Each sprocket will have a different number of teeth. Sprockets are combined together to form different gearing ratios. A typical example will be a cassette with sprockets starting off with 12 teeth, then 13, 14, 15, 16, 17, 18, 19 and 21 teeth.
Older cassettes had 6 or 7 sprockets, while newer models have anything up to 10 sprockets.
Gear shifter and Brake Levers
If you have the luxury of different gears on a bike, you obviously need some mechanism to select and use those gears. Road bikes use a shifting and braking lever combination mounted onto the handlebar. Shimano calls this marvel of biking technology STi or “System Total Integration”, while Campagnolo call their version the “Ergo” system. Basically, all it means is that the rider can brake or change gears without moving his or her hands off the handlebar.
There are many different types of bikes on the market e.g. road bikes, mountain bikes (MTB), hybrid bikes (a mix between road and MTB), downhill bikes etc. etc. For now, let’s concentrate on the road bike.
Frame geometry
Road bikes are divided into two main categories: standard frame geometry and compact frame geometry.
Standard frame bikes don’t have a sloping top tube, whereas Compact frame bikes do. In an effort to cut down on frame weight, bike manufactures brought out the compact frame. Less material is used to build a compact frame, hence the reduction in frame weight. However, it is said that, because you need a longer seat post on a compact frame, all gains in frame weight are negated. The debate continues. I don’t feel that the issue regarding the difference in frame stiffness and handling between compact and standard frames are needed here.
Shorter riders are more likely to use compact frame bikes, because of the smaller size of the bike. However, don’t let your bike dealer confuse you with all sorts of promises of gains in performance and climbing ability with a compact frame. Don’t let anyone rush you into a bike.
Frame material
Bikes can be made from all sorts of materials. Let’s discuss the main types:
Steel
Standard steel frames are heavy. Not many manufactures nowadays make steel frames. Steel rusts easily when scratched or damaged.
Aluminium
Probably the most popular frame material. Most entry, intermediate and high end bikes are made from aluminium. Aluminium is lighter than steel, and more corrosion resistant.
Carbon fibre
Because of its strength and lightness, carbon fibre is an excellent choice for a frame material. However, carbon fibre is pricey. Aluminium/carbon is a popular mix.
Titanium
Titanium alloy frames are very light, but very pricey. Titanium is said to have the responsiveness of steel, the shock absorbency of carbon fibre and the stiffness of aluminium. Titanium bike owners call this the “magical ride” quality.
Frame sizes
One of the most important factors to consider before buying a bike is frame size, and is absolutely vital to your safety, comfort, and enjoyment. An ill fitting bicycle is a bad start, and will lead to all sorts of problems in the end. (We’ll discuss the issue of how and what to measure to determine your correct frame size later on)
How are bicycle frames measured?The most commonly used method to determine frame size is by measuring the length of the seat tube (the tube into which the saddle is inserted – see Figure 1). The measurement is made using one of two methods: Centre to Centre (C-C) or Centre to Top (C-T).
Centre to Centre (C-C) is measured from the centre of the bottom bracket to the centre of the top tube.
Centre to Top (C-T) is measured from the centre of the bottom bracket to the top of the top tube.
See Figure 3.
I have no idea why some manufactures use C-T and others use C-C. If someone out there knows for sure, let me know.
The point is that you should make absolutely sure that your local bike shop (LBS from now on) measures you and sells you the right sized frame. If you are serious about buying a bike, then visit a reputable and professional LBS. Don’t buy a bike at a furniture store. Ask the bicycle salesman one question: “Is this bike sized centre-to-centre or centre-to-top?” If the salesman gets a far away look in his eyes, politely end the conversation and find yourself another bike shop.
Some manufactures, like Trek, produce WSD or Woman Specific Design bicycles. Although the method of frame size measurement remains the same for these bikes, they are designed to accommodate the anatomical differences between ladies and gents (ladies normally have longer legs and shorter torsos than men).
Bicycle components
Following is a list of the standard components that come fitted with a complete bike, and a brief description of each.
Groupset
The groupset refers to the gearing and braking components of the bike.
A groupset will consist of the crankset (also called chainrings or chainwheels), bottom bracket, front- and rear derailleur, cassette, chain, front- and rear wheel hubs, gear shifting/brake levers and brake set.
Some of the higher end groupsets will include components such as a seat post, handle bar and stem, head set and pedals.
Crankset (also called chainrings or chainwheels)
Cranksets come in two flavours: double chainring and triple chainring. Chainrings are classed by the number of teeth they have e.g. 53 teeth on the large chainring and 39 teeth on the smaller chainring. Common sizes are 52-39, 53-39, 53-42 and 52-42 for double cranksets and 52-42-30 and 53-39-30 for triple cranksets. You will find that most entry level bikes come with a standard 53-39 crankset.
Bottom Bracket
The axle and bearing assembly around which the crankset revolves.
Front- and rear derailleur (or derailer)
The front derailleur moves the chain from one chainring to another. The rear derailleur moves the chain from one sprocket to another.
Chain
Probably the most neglected component on a bicycle. Modern bicycles use roller chains (the chain is made up of a bunch of small rollers linked together). When replacing a bicycle chain, remember to specify your groupset and groupset speed (e.g. 8 speed) to your LBS.
Wheel hubs
The axle and bearing mechanism around which the wheels revolve. The rear wheel hub incorporates a “freewheel” or "freehub", which allows the wheel to continue turning without needing to pedal (called “freewheeling” or “coasting”).
Cassette
A combination of gears (or sprockets) combined together to form a cluster or cassette. As with chain rings, cassettes are classed by the total number of sprockets installed on the cassette e.g. a 9-speed cassette will have 9 sprockets. Each sprocket will have a different number of teeth. Sprockets are combined together to form different gearing ratios. A typical example will be a cassette with sprockets starting off with 12 teeth, then 13, 14, 15, 16, 17, 18, 19 and 21 teeth.
Older cassettes had 6 or 7 sprockets, while newer models have anything up to 10 sprockets.
Gear shifter and Brake Levers
If you have the luxury of different gears on a bike, you obviously need some mechanism to select and use those gears. Road bikes use a shifting and braking lever combination mounted onto the handlebar. Shimano calls this marvel of biking technology STi or “System Total Integration”, while Campagnolo call their version the “Ergo” system. Basically, all it means is that the rider can brake or change gears without moving his or her hands off the handlebar.