I wish to explain the very first starting points in understanding why there are so many frame sizes, geometry options, and the most basic understanding of body differences. For the sake of clarity and expediency in this explanation, I will not go into more complex body structure variations, mechanical differences and mal-alignments. This will be addressed, in a later post, as this is much more common and the norm vs the norm being of perfect symmetry and range of motion. The purpose of this post is also to explain why it is almost always best to start with an experienced fitter vs trusting a friend, online fit calculators, or even an inexperienced bike shop salesperson. This is NOT a shot at that person or saying that they don't have your best interest in mind but, rather many just do not possess the detailed and proven knowledge of working with intricate bike fitting techniques and an understanding of bicycle geometry. My hopes are to help clear the air on bicycle manufacturer's geometry differences, why you are not always a certain frame size, and why knowing your own body can overcome someone else's inaccurate recommendation.
A little brief history can start to explain the imposed issues and variations of today. Years and years ago, there was little as 1 size bicycle. Then that became a few sizes, then step thru design in one size, then as many as 9 sizes, and so on. Then about 20 years ago the largest bicycle maker on the planet decided to make three sizes (Small, Medium, Large), mixed with several seat post lengths and set back, as well as several stem options in a dealer kit. They figured this would accommodate most of the people in the bell curve and eliminate making so many sizes, thus reducing costs and improving profit. Sounded like a simple and reasonable idea. However, what most were not aware of is this would really only accommodate an even smaller section of sizes in the bell curve! It took a few years to take hold but, here we are 20 years later and sloping top tubes are the norm. But, this idealistic and selfish approach set the industry back, in terms of proper sizing for the bulk of the adult size ranges, and it's continuance of one key aspect that the industry has greatly neglected for most of it's history-comfort! See, what that bike manufacturer found (and pitched in marketing), was if you sloped the top tube, you would gain stand over height for the shorter inseam person, and one could lengthen or shorten reach by an almost equal proportionality via handlebar stem. This was still mostly targeted at racers or young and flexible riders. They also pitched that this sloping design offered a stiffer frame (smaller triangles) and less weight (less overall tubing). The good news is that a few small frame builders and a few large bike companies saw this as an opportunity. An opportunity to experiment with better stand over clearance for most, and a cool way to raise the front end (head tube), while shortening the reach (top tube). Sure, it made the bikes look a lot different, but this led to bicyclists being more comfortable. This was the start of addressing the needs for the vast majority of riders, recreational not racers. These few pioneers put the insightful/genius into what was a dumb/discriminating new bike geometry.
Now, in 2012, we have most of the major manufacturers making several varying geometry options, as well as more female specific designs than ever before. They are also addressing ergonomics at all the points of contact of the bicycle. This helps, in the vary least, to accommodate not only a wide personal height range but varying flexibilities and personal comfort. See, what is finally being respected here is that if you grab 5 people all 5' 8", they will all require a different set up. Which means different saddle heights, saddle fore/aft positions, different reaches to the handlebars, and different handlebar heights. Going further, those 5 people at 5' 8" might ride everything from a 52cm to a 56cm road bike, and further yet, a tall/relaxed head tube bike frame to a really short/aggressive frame, not to mention an array of ergonomic variations. For instance, Trek makes the same size frame, i.e; 52cm in three geometry options: H1(race performance), H2, H3 (sport performance). Head tube lengths range in 4.5 centimeters, and top tubes range in 6 mm. Specialized makes varying geometries under different model names. For instance the Specialized Roubaix line (endurance road) have taller head tubes vs the Specialized Tarmacs (competitive road). Whatever the brand, understand their descriptions, check out their geometry charts, and try riding both if you can. Head Tubes are also affected by the different headset styles. Integrated, press in, inset, etc. You can either lose 2+cm or gain it, which can cause one frame over the other to fit better. Head Tubes and Top Tubes are more important than seat tube length in my opinion. After performing nearly 9,000 fittings, I have never found a frame not accommodating of a lower handlebar height, even in extreme cases, but have had to do extreme things to make a bike taller in the front to the point of giving up on it. When a frame is near perfection for your needs, the geometry in all the other areas are usually adjusted for optimal and safe weight bias to keep the wheels on the ground and handle safely.
This leads me to underline the point of questioning and being honest with ones self. Asking yourself what type of riding you will be doing. For instance, long rides over 50 miles at a slightly slower pace vs shorter rides under 30 miles at a fast pace. Are you competitive and wish to work at good posture and core strength or is this for fun and excitement along with some good exercise the goal? Add to this, the fact that as we all get older we lose flexibility, lose muscle mass, varying discomforts set in, and generally we ride longer but at a slower pace. These facts and variables are all a part of the vast considerations for proper bike fit set up and impacts the geometry that is beneath you. I have fitted thousands of people that purchased the wrong size bike and I wish to help eliminate that costly mistake. See, not only does this lead to pain and fatigue, but an imbalanced bicycle that can handle in a very unsafe manner. All of these reasons lead to people giving up on cycling as an activity or sport.
Let's point out just a few quick and easy self tests you can perform on yourself, in front of a partner or mirror. Stand with your feet together, legs straight-to just slightly bent, now bend over and reach for the ground. The further you bend over, the strain usually causes more bend in the knee, or the lower spine and hip quits rotating and then the upper or mid spine flexes to get closer to the ground. If you can touch your toes-rate yourself at a 5 (out of10), if you can touch the ground with your finger tips a 6, and so on. The next test is lay on the ground, knees up, feet flat on the ground, arms crossed across the chest, now raise your shoulder blades off the ground and perform a basic sit up. Note if the feet come off the ground, if the hips rotate upwards or down into the ground, and if you shake or are very steady. Now, I have seen people with what appears to be a slight belly but they have a strong core and vice versa with a slim belly with a weak core, but the person with more girth also has to respect this dynamic when your thighs come up to your stomach and you are either in your lowest bar position or even the highest. This test and considerations affect handlebar height (relative to saddle height) and to some degree reach. Being too low not only causes the knees and legs to be pushed outwards, but also causes much discomfort in the back, poor weight distribution, and inefficiency in your pealing mechanics, too name a few problems. Too ignore these factors is a recipe for problems. This is not a pass/fail but, rather acknowledgement of limiters we all have to some degree. One has to respect that your body will change in many ways over a year. What one needs today may vary greatly from a year from now. So, wether you try fitting yourself, or get a bike fitting from a professional, don't go into it thinking I'll set it up one way and just adapt to it. WRONG! Sure, there is always some adaptation, some trade offs, but this sort of thinking only says you are a slave to your bike and it's looks vs the bike will adapt to your bio-mechanical needs for optimal efficiency and comfort. I have played in many many sports, and it amazes me how many people will not use that doctrine in other sports but they will in Cycling. To minimize pain, limit injury, increase efficiency, therefore improving performance, one learns to use the right equipment, run correctly, kick correctly, skate with more finesse according to their body and ability. When it comes to cycling....looks and weight of the bike often precedes correct positioning, comfort, and learning how to pedal with greater efficiency for quicker performance achievements. Most pro's in any sport, get from point A to Z by working with various experts, at some point in their career, to overcome inefficiencies, work smarter, and correct body mechanics. Even if all you aspire to do is ride in the park, there are lessons and tips to respect and utilize to help minimize problems and increase the fun and excitement in the sport of cycling! I should add that Pro's will NOT ride the wrong size bicycle, no exception! Many pro's through the years have even ridden custom bikes built for them but painted and decaled as the sponsored stock bike manufacturer.
So, in summary, seek out shops or fitters with experience and are up to date in training, use accurate fit measuring systems and devices, don't be afraid to ask them detailed questions regarding their fit methods and reasons for doing certain things, you can get a fit from a different store than where you purchase from but again seek out that fitters success, test ride different style geometries and set ups, be honest with yourself and your body needs over the bike's sexiness, and lastly respect what the people who are on the bikes your interested in have to say vs the manufacturer.
In my next post, I will focus on frame materials, more in-depth frame geometry definitions, and custom vs stock.
Happy Riding!
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