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.
3-2-1- Contact
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
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.
A great place to start fitting the saddle is to put the saddle in the forward most position that allows the rider to take his hands off of the bars and maintain the body position without straining or feeling fatigue. You should not feel like you're about to fall forward when you let go of the handlebar. If the position with the hands on or off the bars feels neutral to your back muscles you know that you aren't using your arms to support your body. If you are not balanced, your arms and shoulders will get tired on a long ride. Try to balance roughly 55% of your weight rear and 45% forward.
So A Cyclist Walks Into A Bar:
Handlebar position also depends on a rider's needs and goals. For drop handlebars the size should equal the distance between the ends of the clavicle. I am a size 42. A shorter, more upright stem brings the bars closer for comfort and a more upright position to view the road far ahead. Low bars allow for a more aero position and a long stem helps with control at higher speeds. A rider should have the elbows slightly bent on the hoods and not locked. Handlebars should be even and not pointed up or down. That is not a great way to adjust the reach to the levers and brakes.
Even after a fit some riders need to fine tune their position. Here are a few helpful links to help.
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The late Sheldon Brown lives on the interwebs and has a wonderful piece about pain. His entire site hosted by Harris Cyclery is a great source of info.
Gearing and other calculations can be found here.
Last week I turned in a good 90 mile ride and I knew I had to increase the length to get into shape for my upcoming 260km ride to Kaohsiung. Last week I had a pretty bad flat and it did quite a bit of damage to the sidewall of my rear tire. I have been riding a set of Continental GP4000 tires for two and a half years and I love them. Still, with 7000 miles on them they are getting a bit worn. With tires, as they start to wear down they flatten out and feel hard and fast. The speed isn't so bad, but the level of comfort plummets and the level of confidence in the tire plummets as well. I went out Saturday to find a replacement set and couldn't find any in all of Taichung. Many places carry the tires, but were sold out. The Contis are a well made tire with good road feel, speed and enough tack to grip the road on hard turns. They have been very reliable as well. It took me over two years to get my first flat. My Saturday odyssey took me to ten or more shops and what surprised me most were the 'alternatives" some of the shops tried to offer. It told me a lot about the differences between shops in Taichung. I am sorry, but a "Road King" or a Bridgestone is not a suitable replacement for a Conti GP. In my opinion, tires are not one of the components you can compromise on. The right tire plays such an important role in handling, comfort, performance and safety. Tires can last for a couple years, so I am not about to waste money on something I will regret for two years. I also learned how uninformed many shops are on tire width. Most shops carry 23c tires because that's what the pros have. There is no difference in speed between the 23c and 25c tires. If anyone tries to tell you as much then they don't know tires. A 25c offers more comfort without a drop in performance. A lot of pros use 23c because they are slightly lighter. In Sunday's Paris-Roubaix they were using 25-28c tires. Grrrr! I have some nice 25c on order, but I had to endure several hours in the saddle on old, hard tires with structural weakness. 
