Wednesday, April 14, 2010
Quite a few times lately I have been made aware of folks who really want to be biking, but when they go out and get a bike they end up feeling uncomfortable and then feel like trashing their bikes to get a new one or lose interest in cycling all together. "Road bikes are uncomfortable!"
Those are some pretty drastic measures and the pain can quickly spread to the bank account. There are smarter ways of going about looking for a bike than simply trial and error.
On the sidebar I have a few posts about geometry and material, but more importantly comes the subject of fit.
Anyone who is shopping for a bike should get fit by a professional. I don't want to offend anyone, but Giant seriously sucks at fitting and I would recommend going elsewhere for a professional fit. A proper fitting bike doesn't just mean a more comfortable experience, but it can also mean the difference between actually riding the bike and laying around the house with an injury.
I still stand by my belief that for road riding (predominantly riding on paved roads) a type of drop bar road bike is ideal as opposed to a mountain bike, although some flat-bar urban commuters can work well as urban assault bikes, but they are still configured with road bike geometry. Therefore, I am going to keep this post to road bike fitting.
The rider has three major contact points with the bike. The location and relation of these points is integral to determining fit--The seat, handlebars, and crank/pedals. If these points are not in the right place then riding a bike can be a heap of pain as it will not be ergonomically correct for the rider. When I see riders on a poorly fitting bike I always remember when my grandfather, who was a very stubborn man, went to a yard sale and picked up a set of gloves. He realized they were two lefties. Rather than go through the hassle of taking them back, he decided to simply wear them anyway. This resulted in a serious case of tendonitis on his right hand because his thumb was spending too much time under stress. The same thing can happen on a poorly fit bike.
The crank length determines how large a circle the rifer makes with each rotation and varies between riders. Most cranks typically run between 165mm to 175mm in length. Most people fall into the 170mm-172mm range. I have heard of one method for determining the crank length being 18.5% of the distance from barefoot of the floor to the top of the femur. All numerical calculations are just suggestions. Some personal preference comes into play as some riders might like to spin faster with a smaller crank. Once you get this measurement figured out you can get your saddle height figured out. The Seat Tube length plays a factor here, but it is more aesthetic within a certain range. The ST will, however, determine stand-over height; a key element of the fit.
Saddle Sores: "Hey, your seat is too low!"
Damn, if I don't see more low saddles in Taiwan. I see more people going down the road with their legs sticking out at weird angles, weaving all over the road at no speed.
The proper saddle height allows the rider to stretch the legs out to their optimal extension to maximize the rider's efficiency. On a good ride you just don't want to waste energy on a poor stroke. Luckily, a poorly adjusted saddle usually makes itself known through a very obvious knee pain.
The saddle should be level. A forward tilt pushes the rider into the bars and an up-tilt pulls them off the back. For a basic start to the fitting process the saddle should be high enough so that you can just touch the floor with your tip toes. When pedaling your knee should be slightly bent. The balls of your feet should be over the pedal axle and you should not rock in the saddle.
The seat is a very personal preference. A saddle should match the rider's "sit bones", those little pointy parts of the pelvis that stick out when humans curl their legs. Although a rider may have a real fat ass... their sit bones may be quite narrow. The skeletal frame makes this determination rather than the amount of mass. Women typically need a wider seat due to the difference in reproductive physiologies.
A saddle can also be adjusted forward and back to achieve different feels and fits. It determines the size of the cockpit. A good cockpit on a bike should be a little stretched out and opened to allow for better breathing. Some seat fittings can be tuned to be more or less aerodynamic. More importantly, it balances the rider behind the bottom bracket. The balance will play a huge part in comfort and efficiency. It is important to know the length of the Top Tube to be sure your body can comfortably fit on the bike without being too stretched out or scrunched up.
A totally upright position your head, knees and feet are inline and the body is balanced. Now imagine someone turns on a wind machine. You will need to bend forward to stay balanced. As you bend your butt moves back. This is similar to riding a bike. If you are too upright you waste valuable energy battling wind resistance. You will work more and fatigue faster. A totally aerodynamic position is generally not comfortable to all but circus contortionists. A good tradeoff results in an bent position, bent, and balanced.