Bike Maintenance Class: Week 2, Basic Fit, Component Materials, and Brake System

Bike Maintenance Class: Week 2, Basic Fit, Component Materials, and Brake System

Judging Bike Fit: Stand Over Height

Finding a bike that fits correctly is important, but its also is mostly about personal preference. So what should you look at?
The most basic component of bike fit is stand over height. On the bike its the distance from the top of the top tube to the ground. On the rider this measurement should be at least an inch or two less than the distance from your crotch to the ground. If you don't have that clearance you could really hurt yourself when dismounting. Stand over height differs between bikes that are the same size based on how the manufacture measures size and the bikes geometry.

This will tell you if a bike fits you most of the time. While there are other components to bike fit, most of them are adjustments, which we will cover later in this class.

Frame Materials

Bikes frames are made out of three types of material:

• Steel - If your using your bike on a daily basis and have to lock it up outside sometimes(but never overnight!) steel is what you want. It can take more abuse than aluminium or carbon and sometimes even be realigned after a particularly hard impact that would total other frames. Avoid frames made of high carbon or high-tensile steel (some times called hi-ten). Instead look for frames made of an alloy such as chromoly (chromium-molybdenum) as they are lighter, stronger, and resist rust better. If the frame doesn't have a sticker stating what its made of, there's a good chance is straight gauge, high-tensile steel.
• Aluminium - Stiffer and lighter than steel, aluminium is ideal for road bikes where you want to be putting down maximum power, or in a bike with suspension where you aren't relying on the frame to absorb shock. The thin tubing in nicer aluminium bikes is prone to dents and dings so be careful when leaning it up against poles and street sights to lock it up. Also, if your frame ever gets bent, that it, game over, time for a new frame.
• Carbon - Carbon fiber frame are made by laminating sheets of carbon fiber together with epoxy in a vacuum mold. This gives designers a great deal of flexibility in design that can result in extremely light bikes that are stiff in some area and good at absorbing vibration in others. The down side is that carbon fiber is brittle and comparatively more expensive. If your riding a carbon bike, you shouldn't be locking it up anywhere outside.

Butted vs Straight Gauge: Double and triple butted tubing is thinner in the center of the tube than at the ends, taking pounds of the weight off a frame and providing a more comfortable ride.

Saddle and Cockpit Set-Up

Saddle Height and Position

• Level

Your saddle should always be about level or tipped slightly towards the front of the bike. Level is measured from the highest point on the rear of the saddle to the hightest point on the front of the saddle (the nose). You can change this slightly but if the saddle is tilted to far forward, your going to put extra pressure on your wrists, to far back and the saddle's nose is going to start putting pressure on bits you wish it wouldn't.

• Height

When in the saddle, with the peddles at 11 and 5 o'clock, place the heels of you feet on the peddles (you might want to get a friend to hold the bike steady for you). Adjust your saddle so that the extended leg bends slightly at the knee. The idea is the more leg extension you can get, the more efficient the stroke, but you never want your leg to extent fully as this is very bad for you knees.

• Setback

When in the saddle, with the peddles at 3 and 9 o'clock, the front of your leading knee should be plumb with the peddles spindle.

Handlebar/Stem Position

Seeing as you can have anything from drop bars to 5" risers on a bike, this is mostly personal preference. Just make sure you knees aren't going to hit the bars when your taking a sharp corner. A more upright position gives you better visibility while a lower position will make you more aerodynamic.

Cockpit Set-up

All of this is personal preference, but here's a starting point.

• Flat Handlebars
• Drop Handlebars

Breaks

System Overview/Styles

Calliper, Cantilever, and Linear Pull

Quick Release

===Replacing Cable and Housing