Friday, March 25, 2011

Bike frame sizes

Bike frame sizes, how to measure and pick the correct size bicycle

Bicycles come in a variety of frame sizes and styles. One model of bike might have two or three frame sizes meant to fit different sizes of riders. While people of average height can ride most model sizes comfortably, and while the seat height can be raised or lowered several inches in each direction to customize your ride, both taller riders and shorter riders want to pay particular attention to the frame sizes they get. If a taller rider gets a frame size too small for them, they will experience an uncomfortable ride and they will pedal in an inefficient manner. If a shorter rider gets a frame size too large for them, they will find it difficult to get on the bike and will experience problems with balance when coming to a stop (as they won't be able to get their feet on the ground without tipping over.)

Here are some tips to determine if a bike frame is right for you:

Sit on the bike
When you are sitting on the bike, and the pedal is at the lowest position, is your leg completely extended? You should be able to touch the ground with the tips of your toes when you're sitting on the bike. An extended leg will give full power when riding the bike. You're more efficient (why waste energy?) and protected from strain on your knees. If you pedal the bike and your knees are parallel to the ground at the highest point, this bike is too small. If you can't touch the floor when you're sitting on the seat, the bike is too high. Keep in mind that most bikes allow for an adjustable seat post, and many models, such as folding bikes, do not have frame sizes. You can simply move the seat to achieve the best position.

Check your height
Many bikes are measured in either inches or centimeters. Sizes can vary from rider to rider, but generally, we follow these guidelines:

16" (40 cm) frame is most suitable for riders ranging from 5' to 5'8" in height.
An 18" (45 cm) frame is most suitable for riders ranging from 5'7" to 6'1" in height.
A 20" or 21" (50-53 cm) frame works for riders 6' and up.
Keep in mind, these ranges are just approximations. You'll find varying ranges listed elsewhere, as there is no set standard. In reality, no matter your height, people have different builds. Two people of the same height can have drastically different proportions: one might have long legs, while the other might have shorter legs. To be as accurate as possible, you'll want to measure your inseam (standing up, along the inside of your leg from your crotch to the floor.)

How to measure the bike
Okay, so you've taken your measurements. Now what? The frame measurements (16", 18", 20", 21" or what have you) measure the vertical seat tube (not to be confused with the adjustable seat post) on the main frame. The measurement begins from the bottom bracket (the cylindrical part of the lower frame in which the pedal cranks are affixed) and goes up to the top of the seat tube, the point at which the seat post enters the main frame.

Now, before you get out your measuring tape to go to the bike store, here is another point of reference: When standing in front of the seat, the highest point of your inseam should be at least one inch above the top tube of the frame. If you cannot stand flat over the top tube of the bike, it is too large.

Note: The frame measurements are not to be confused with the wheel sizes. Wheel sizes can come in at 16", 18", 20" (most BMX's), 24", 26" (the standard wheel size in the U.S.), and 700C/27" (often found on racing bikes and European models.) The wheel measurements are independent of the frame size; when a bike is labelled as an 18" bike, the measurement is referring to the frame size specifically.

Best tips for cycling

Tips for the Best Cycling

About 90 million American adults ride a bike at least once a year, nearly 30 million cycle regularly for recreation, and a few million even commute by bicycle, according to a recent article in American Demographics. Those numbers may rise in the next few years, thanks to federal legislation that encourages local communities to build cycling into their transit plans. That's good not only for the environment, but also for the nation's health, since cycling is one of the best forms of exercise around. It gives the heart and circulatory system a workout; it puts little stress on joints (except perhaps the knees); it can burn 400 to 700 calories per hour; and if you own a bike, cycling is free and can be done just about anywhere.

Here are some steps you can take to improve cycling performance, safety, comfort, and enjoyment:

Use your head

1. Absolutely crucial: always wear a helmet. Of the nation's 800 annual cycling deaths, head injuries account for about 60%. If all cyclists wore helmets, perhaps half of these deaths and injuries—especially in children—could be avoided. Choose a bright color, and make sure the helmet fits properly. It should sit horizontally on your head and shouldn't move about.

Do the right thing

2. Brake right. To exert optimal pressure, brake with your hands at the ends of the levers. For a quick stop, as you press the brakes firmly, slide your buttocks to the very back of the saddle. This will keep the rear of the bike down so that you don't flip over the handlebars.

3. On a long downhill, don't stay on your brakes. That may overheat the tire's rim and could cause a blowout. It's safest to "feather brake"—that is, tap the brakes, applying intermittent pressure. This is wise in wet weather, too.

4. Don't pedal in high gear for long periods. This can increase the pressure on your knees and lead to overuse injuries such as biker's knee. Shift to lower gears and faster revolutions to get more exercise with less stress on your knees. The best cadence for most cyclists is 60 to 80 revolutions per minute (rpm), though racers pedal in the range of 80 to 100 rpm.

5. Going uphill, shift gears to maintain normal cadence. On a long hill, conserve energy by staying in your seat.

6. When cycling at night or when visibility is poor, wear brightly colored, reflective clothing, and use your headlight. In fact, wearing bright colors is a good idea at any hour. Also consider a rear strobe-type light (attached to the bike or your belt) to enhance visibility at night.

Easy rider

7. Make sure your bike fits. Handlebars, saddle, wheels, gears, and brakes can all be adjusted to match your size and riding ability, but the frame has to fit from the start. To find the right frame size, straddle the bike and stand flatfooted: on a road bike, there should be one to two inches of clearance between your groin and the top tube. On a mountain bike, the clearance should be two to three inches or even more.

8. Position the saddle right to protect your knees. At the bottom of the stroke, your knee should be only slightly bent. If your knee is bent too much, the seat is too low, and you will lose stroking power and strain your knees. If the knee locks when extended, or if you have to reach for the pedal, the seat is too high, which can also stress the knee. The saddle should be level.

9. Position the handlebars correctly—one inch lower than the top of the seat. Drop handlebars (preferable because they allow you to change your riding position) should be about as wide as your shoulders or slightly narrower. Some cyclists who suffer from neck or back discomfort may prefer upright handlebars.

10. To avoid saddle soreness, get the right seat. The hard narrow seats on racing bikes can be particularly uncomfortable for women, who tend to have widely spaced "sit bones." Special anatomically designed saddles—wider and more cushioned at the back—are easy to install. Gel-filled saddles or pads or sheepskin pads can ease the pressure and friction.

11. Change your hand and body position frequently. That will change the angle of your back, neck, and arms, so that different muscles are stressed and pressure is put on different nerves.

12. Don't ride in the racing "drop" position (with your hands on the curved part of the handlebars) for a long time. This may cramp your hands, shoulders, and neck.

13. Unless you're an experienced cyclist, don't use those special aerodynamic handlebars—shaped like an upside-down "V"—which let you lean forward on your forearms and thus reduce wind drag and increase your speed. These increase the risk of injury.

14. After a long uphill, don't coast downhill without pedaling. As you climb up the hill, lactic acid builds up in your muscles and can contribute to muscle soreness. By pedaling lightly but constantly while coasting downhill (even if there's little resistance) you can help remove the lactic acid.

15. Keep your arms relaxed and don't lock your elbows. This technique helps you absorb bumps from the road better.

16. Wear the right shorts if you cycle a lot. Sleek cycling shorts have less fabric to wrinkle or bunch up, so there's less chance of skin irritation. For extra protection, choose cycling shorts with special lining or padding to wick away perspiration and no seams at the crotch.

17. Don't wear headphones. They can block out the street sounds you need to hear in order to ride defensively. Cycling with headphones is a misdemeanor in some areas.

Good road sense

18. Ride with traffic, obey all signs, and give right of way to cars.

19. Use hand signals to alert drivers to your intentions.

20. Try to make eye contact with drivers as you pull into an intersection or make a turn, so they know your intentions and you know that they've seen you.

21. Don't ride side by side with another cyclist.

22. Watch out for storm drains, cattle guards, and rail-road tracks. They're all slippery when wet. And if you don't cross them at a right angle, your front tire may get caught.

23. When cycling in heavy traffic, on a narrow road, or on winding downhill roads, ride in the lane with the cars, not to the side, where you're not as visible and may get pushed off to the side. Of course, if a car wants to pass, move out of the way.