Bikes seem pretty simple. A metal frame with two wheels, a seat and handlebars. Not much to them, right?
Not so fast. Modern bikes are precision machines crafted in a multitude of ways to suit all types of riding. Many materials and technologies are used to build different types of bikes, leading to a wide range of prices. You should never buy a bike simply based on the price, though – spend a little time to figure out which bike style and components will suit you best, then look for the bike that fits your needs.
Sierra Trading Post provides many specifications on the bikes and bike hardware we sell. This guide will help you to understand what all the strange cycling terms mean, which components do what, and how to select the right bike.
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The Basic Designs - Bicycle Categories
Like all outdoor gear, the best way to select a bicycle starts with figuring out what you’ll be using it for. There are several major bike categories to consider:
Road Bikes
Road bikes are designed to be very lightweight and sleek, with narrow tires for low rolling resistance that have a smooth surface to grip the pavement. These bikes are ideal for very long rides on developed roads, and make good one-person commuter vehicles for longer distances.
Shop Road Bikes
Mountain Bikes (MTBs)
Mountain Bikes are sturdier than road bikes, and offer supreme shock-absorption and wide, heavily treaded tires for gripping a variety of surfaces. There are two main divisions of MTBs: “hardtails” with front suspension only, and smoother-riding bikes with front and rear suspension. Hardtails are generally less expensive and offer a more efficient ride (they weigh less); full-suspension MTBs are the best for covering lots of rough trails and drops. MTBs are the way to go if you usually ride off-road, with less riding on paved streets.
Mountain Bikes (MTBs)
Cruisers/Comfort Bikes
Cruisers and comfort bikes are casual weekend bikes for short, leisurely rides around the neighborhood and park. What they lack in performance features they make up for in a lower cost and added comfort for a more enjoyable – if slower – ride.
Cruisers/Comfort Bikes
Commuter Bikes
Commuter bikes are tougher than cruisers and heavier than competitive road bikes. These are solid, dependable, no-frills bikes designed to ride for many miles and last many years. They are not designed for off-road use, but are great for daily rides to work and offer a very comfortable upright riding position.
Commuter Bikes
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Bike for your Budget
You’ll find a wide range of bike prices out there, and this is due largely to the materials used and the quality of the components. Know this: The lighter a bike is, the more expensive it is. Even the loss of a few ounces can significantly increase the cost.
If you are a competitive long-distance rider or regularly ride with (and against!) your buddies, an extra pound can decrease your performance on a bike. However, if you’re just a casual beginner rider, you might not notice this weight difference and can consider a less expensive bike.
Bikes with specialty frames and carbon components are the lightest, while steel-framed bikes are the heaviest. Aluminum alloy frames fall somewhere in the middle. Here are some general guidelines based on the manufacturer’s original retail price, listed on our website with each bike (not based on Sierra’s discounted price!):
- Less than $500: Heavier frame and lower-end components. As long as you buy from a good brand, you should get a decent bike.
- $500 to $1,200: Midweight frame with mid-range to higher-end components. These bikes are good for intermediate riders who will appreciate the smoother parts and lighter road weight.
- $1,200 or more: A lightweight frame with only high-end components. Any serious cyclist will want to focus on this category.
Buy as much bike as you can, so you won’t soon regret your purchase. If you underestimate your potential (maybe you have an inner Armstrong!) and get a bike designed for riders at or below your current ability level, you’ll have to upgrade in the near future.
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The Sum of the Parts – Bicycle Components
A red arrow will highlight each component in the
diagram below when you click on the corresponding link.
The Drivetrain
This is the set of components (besides your legs!) that are involved with powering the bike.
Derailleurs (front/rear)
Derailleurs serve as the transmission of a bike. They are the mechanisms that move the chain from sprocket to sprocket when you shift gears. The derailleur got its name because the chain guide “derails” the chain to another sprocket whenever the shift levers are adjusted.
Shifters
Shifters, located on the handlebars, are designed to be manipulated with the fingers and thumbs. They connect to the derailleurs via thin cables.
Cassette
"Cassette" is the term used to describe the entire set of sprockets on the rear wheel that drives the different gears.
Bottom Bracket
The bottom bracket is the axle and housing that connect the crank to the frame, located where the down tube, seat tube and chain stay meet.
Crankset (Crank)
The crankset connects the bottom bracket to the pedals and is responsible for transferring the power of a rider’s legs into the rotational motion of the rear wheel, via the chain.
Crank Arms
The crank arms connect the crankset to the pedals.
Chain Rings
Chain rings are the front sprockets for a chain and are considered part of the crankset.
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Wheelset
Rims
Rims are usually aluminum, but may be carbon (top end) or steel (low end). They often have a smooth, parallel surface on each side for rim brakes. Rims sometimes have double-wall construction for added strength, but always have spokes to act as a framework and maintain their shape.
Tires
Tires vary widely in their construction based on the intended usage. They may have an inner tube (traditional “clinchers”) or may come tubeless (“tubulars” – which have a lower rolling resistance and get fewer flats than clinchers, but cost more and can be harder to field service). Bicycle tires are wide and knobby for MTB use, but narrow and smooth for road usage. The wider/ knobby MTB tires provide better traction on varying trail surfaces, while the smoother tread of road tires increases traction on pavement, because the flexible tire can hug the texture of the road itself. The materials used to construct bike tires include rubber, steel wire or Kevlar® edge cording, and cloth fabric.
Tire Valves
Tire Valves usually come in one of two styles. Schrader valves are universal and allow you to fill your tires anywhere you can fill a car tire; they’re the valves used on most bicycles. High-end bikes sometimes use Presta valves, which handle a wide range of air pressures well. An adaptor from a bike shop is needed to fill tires with these valves with a Schrader pump.
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Frame Set
Shop Bicycles and Bike Frames
The frame is the skeleton of the bike. A bike frame generally consists of one large “triangle” made up of three tubes (the top tube, down tube and seat tube), plus two smaller pairs of bars (the seat stays and chain stays ) that link the back wheel to the seat tube to form a second triangle. Another metal tube, called the head tube, is attached where the top tube and down tube meet and houses the headset.
This paired-triangle frame design is called a “diamond frame.” The tube sections making up these triangles are smooth and cylindrical on most bikes, but may also be angular or octagonal in a cross section (called “hydroformed” tubes).
The “geometry” of a bicycle is a set of specifications mostly taken from the lengths of the various tubes and the angles between them. This geometry will differ depending on the type of bike. For example, the handlebars on a road bike are set low and far away from the seat to enable the rider to get into the most aerodynamic position possible. Conversely, the handlebars on an MTB, commuter or cruiser are set higher and closer to the body for a comfortable, upright ride.
Frames may be made from steel, aluminum alloys, titanium or carbon fiber. The material type significantly affects the weight of the bicycle.
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Other Bicycle Components
Shop Bicycle Hardware and Accessories
Handlebars
Bike handlebars come in several styles, notably drop handlebars on road bicycles and flat or “riser” handlebars on most MTBs and commuter bikes. Handlebars also provide a mount for the brake levers and gear shifters.
Brake Levers
Bicycle braking is done via hand levers that use either “Bowden cables” (taut but flexible cables housed within other hollow cables) or hydraulic lines to transfer mechanical force to friction pads on the wheels.
Headset
A bike’s headset is the group of smaller components that collectively provide the rotating interface between the fork and the frame. The headset is located within the head tube.
Stem
This part connects the handlebars to the steer tube of the bicycle’s fork and is generally constructed of the same materials as the frame.
Brakes
There are three main types of bicycle brakes: rim brakes, disc brakes and internal hub brakes.
- Rim brakes are the most common, consisting of rubber friction pads that grip the outside of the wheel rim when the brake levers are squeezed. They are inexpensive and easy to repair or adjust. Road bikes use only this type of braking system.
- Disc brakes utilize a metal disc attached at the wheel hub, with calipers on the frame or fork that squeeze pads against the disc. These brakes are becoming more popular on MTBs and commuter bikes despite their extra weight, due to better performance than rim brakes in wet, icy or muddy conditions. Disc brakes may come either hydraulic or mechanical.
- Internal hub brakes or drum brakes, are a good choice for wet or dirty conditions. They involve internal pads that press outwardly into the hub’s shell; since they are internal, they require little maintenance and are largely unaffected by poor conditions. The downside to internal hub brakes is that they are sometimes less effective than other brake types in normal conditions and may require more time to stop. These brakes are generally found on comfort cruisers.
Fork
The fork is the component that links the front wheel to the frame at the head tube. A crown links the two fork blades to the steering tube. Many mountain bikes offer special suspension forks with ample shock absorption. The amount of compression the fork provides in these suspension forks is called “travel.” The greater the travel distance, the more recoil the shocks will offer.
Rear Suspension (Shock)
On full-suspension mountain bikes, the frame includes a shock integrated into the rear of the bike as well as the front suspension fork. The recoil of these shocks on full-suspension bikes is called “rear travel,” and works in tandem with the front suspension fork to cushion your ride on especially rough terrain. Rear suspension also enhances your ability to maintain contact with the trail, but it increases the weight of the bike.
Saddle
The saddle is the seat of the bike. Different styles include extra-padded models, gender-specific models, and extra-narrow performance saddles. Most saddles have a tough synthetic or leather cover. Saddle comfort is key to a good ride, so you may want to consider upgrading the saddle before any other components on a bike.
Seatpost
The seatpost is the tube that connects the frame to the saddle. Most seatposts can be extended and adjusted to the rider’s height and riding preferences.
Pedals
Modern bike pedals include basic flat platforms, toe cages and clipless pedals. Toe cages keep your feet in place and increase pedal efficiency; clipless designs require special shoes to lock the feet in place onto the pedals, but offer the most efficient motion on both the downstroke and the upstroke.
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Deciphering Size Charts
Nearly every bicycle offered by Sierra Trading Post comes with a chart that provides specifications for a bicycle’s components (this chart is not available for comfort bicycles). The information in a bike’s size chart is usually referred to as its “geometry.”
Example of Bike Size/Geometry Chart
| |
XS |
S |
M |
L |
XL |
| Head Angle |
68.5 |
69 |
69 |
69.5 |
69.5 |
| Head Tube Length |
3.9 in. |
4.3 in. |
4.7 in. |
5.3 in. |
5.9 in. |
| Top Tub Horizontal |
21.3 in. |
21.7 in. |
22 in. |
22.4 in. |
23 in. |
| Seat Angle |
74 |
73.5 |
73 |
73 |
73 |
| Bottom Bracket to Top of Seat Tube |
13 in. |
14.6 in. |
16.1 in. |
18.1 in. |
20.1 in. |
| Bottom Bracket Top Tube |
11 in. |
12.6 in. |
14.2 in. |
16.1 in. |
16.1 in. |
| Chain Stay |
16.9 in. |
16.9 in. |
16.9 in. |
16.9 in. |
16.9 in. |
| Bottom Bracket Offset |
-32 |
-32 |
-32 |
-32 |
-32 |
| Stem Length |
60 |
60 |
60 |
60 |
60 |
Bicycle size charts on SierraTradingPost.com represent the manufacturer’s own specifications. As a result, different bikes have different types of geometry represented, and specifications may be provided in multiple units of measure (mm, inches, etc.). Also, manufacturers may measure geometry in different ways, such as from the center of one component to the center of another (C-C), or from the center to another component’s top end or edge (C-T). Be aware of this if you are comparing bicycles from different brands, so that you aren’t accidentally comparing apples to oranges.
Note: Always check with each bicycle brand for specific information on how their bicycles are measured and to determine how to find your best fit.
Some road bikes have compact or “sloping” geometry in which the top tube slants upward from the seat tube to the head tube. This results in increased range of stand-over heights, possible weight savings and a lower center of gravity.
What do these geometry specifications mean? Here are some of the major categories you might find on a bicycle’s size chart, and the ways they are generally measured:
A red arrow will highlight each component in the
diagram below when you click on the corresponding link.
Bottom Bracket
Many of the important measurements for a bicycle start at the bottom bracket. Distances are measured from the bottom bracket to another part of the bike (i.e., to the top tube). These measures are taken from the center of the bracket axle.
BB Drop
The height difference between the rear wheel axle and center of the bottom bracket. This is the difference in vertical distance (not the actual distance between the axle and bracket).
Bottom Bracket Height/ Clearance
This is the vertical distance from the center of the bottom bracket to the ground.
Chain Stay
This is the length, usually given in inches, from the center of the bottom bracket to the center of the rear wheel axle (or dropout).
Fork Length
Total fork length is measured from crown to front axle.
Head Angle
The angle between the head tube/ headset and an imaginary wheel-to-wheel axle centerline. A steeper head tube angle approaching 90 degrees will offer more responsive steering.
Head Tube Length
The length of the entire head tube, from top edge to bottom edge.
Seat Angle
The angle formed between the seat tube and level ground, or between the seat tube and top tube. Always less than 90 degrees; usually around 72-76 degrees. A steeper seat tube angle (closer to 90 degrees) will put the rider in a more aerodynamic – but less comfortable – riding position.
Seat Tube Length
A measure from the center of the bottom bracket to either the center or top of the top tube. This measure is sometimes listed as the “size” of a bike – especially regarding road bikes.
Stand-Over Height
A measure taken from the center of the top tube to the floor, in vertical distance. For MTBs, this is the best measure to determine your ideal size – it should simply be 2-5 inches less than your inseam (distance from crotch to floor), based on your preference.
Stem Length
Just what it sounds like. This size is especially important when sizing the right road bike; stems are relatively easy to swap out, and having the right stem length can help you fine-tune your custom fit on a bike. Stems generally range in length from 90 to 120 mm for MTBs and 90 to 130 mm for road bikes. Women’s specific models may have even shorter stems.
Top tube
This measurement is taken from the center of the seat tube to the center of the head tube. If the specification instead lists top tube horizontal or effective top tube (for bicycles with compact or sloping geometry that lack a perfectly horizontal top tube), this refers to the horizontal distance from the center of the head tube/ top tube intersection to the center of the seat post.
Wheel Base
This is the total length from the front wheel axle to the rear wheel axle.
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Note: Length measures are listed in various units – usually inches, centimeters or millimeters – depending on the preference of the vendor.