Frame Dimensions for a road bike

The very first and most important thing to consider is frame sizing and geometry. Frames are sized by seat tube length (A) by convention. This is the vertical dimension of a frame. Equally important is the top tube length (B) or virtual top tube on frames with a non-horizontal top tube. This is the horizontal dimension of a frame. A "square" frame has a seat tube length that is equal to the top tube length. This is a "standard" size. This means that a 56 cm frame has a top tube (or virtual top tube) that is also 56 cm. These frames work fine if you have a "normal" torso and leg length proportions. It gets more complicated if your torso is relatively long compared to your legs or vice versa. This is when you have to really look at frame specifications. For instance, a 6 foot tall male that has only a 32 inch inseam cannot use a standard "square" frame comfortably. He will actually require a 54 cm frame with a 56 cm or so top tube. This frame matches his body: the top tube is longer than the seat tube to better fit his long torso. The opposite can happen as well: a person with long legs compared to the torso length will require a frame with a relatively longer seat tube compared to the top tube. These "non-square" frames also require compensatory changes in "normal" frame geometry such as shorter or taller head tube, differing fork rakes, changes in seat tube angle, etc. to make the frame handle correctly.

Frame Materials
The next thing to consider is frame material. The big four are titanium, carbon, aluminum, and steel. These materials vary greatly in characteristics from cost, weight, stiffness, and how they dampen different kinds of vibration. Their relative characteristics are listed in the chart below.

Material               Cost              Weight              Stiffness         Vibration Dampening    Titanium            $$$$$            Very Light            Medium      Excellent/High Frequency                                                                                            Excellent/Low Frequency Carbon              $$$$$           Super Light          Med./High    Excellent/High Frequency                                                                                          Good/Low Frequency Aluminum         $$-$$$            Vey Light            High            OK/High Frequency                                                                                           Poor/Low Frequency Steel                 $-$$              Med.-Light           Low-Med.     Good/High Frequency                                                                                           Good/Low Frequency

Road bike terminology

Many of the listed characteristics can also vary depending on tubing design. For instance, low diameter carbon fiber has only medium stiffness while the same material in a large diameter has a high level of stiffness. The same holds true for steel. It can have low to medium stiffness depending on the diameter of the tubing. Costs can vary tremendously within the same material: mass produced frames of a particular material will be much less expensive than a hand made frame, sometimes less than half the cost.

Most modern road bicycles now come with a carbon fork. This is an excellent application of carbon’s inherent characteristics: excellent high frequency vibration dampening to increase comfort while having a good stiffness to weight ratio for good tracking in turns. The material’s stiffness aids in lateral stability of the fork which keeps if from deflecting too much while leaned over. If you have chosen a bike that has a steel or aluminum fork, one of the best upgrades you can make for your bicycle second to wheels will be a carbon fork, especially for the increased comfort it will give you on those longer rides.

Component Group
The next step will be to choose which component group will be hanging off your new frame. There are two major manufacturers: Shimano and Campagnolo. There are some minor players like SRAM, Sachs and others but you will usually be dealing for the most part with the big two. Both Shimano and Campagnolo offer component groups at several price points. You pretty much get what you pay for: with each step up the component group ladder for each manufacturer, you gain a fairly big advantage in functionality, weight and durability. This holds true for each component group except for the premier offering from each company. At the very top of the manufacturer’s component families lies a premier line: Shimano’s Dura-Ace and Campagnolo’s Record. These component groups cost substantially more than the level just below and offer only a slight gain in functionality, weight, and durability. For the motocross racer it would be very hard to justify the big cost difference for this small gain. Think of these premier groups the same as you would a Titanium bolt kit for your MX bike: yeah, you do get a slight weight savings, it costs a lot, it looks trick, and man is it cool but what about actual performance gain? It is hard to deny how cool and how trick Dura Ace and Record are but…

Hope this isn't what you had in mind!

Wheelsets
Now you will have to choose a wheelset. Over the last 10 years the gains made in this department are huge. Wheels have lost a lot of weight and gained durability at the same time. Cost is still an issue here and again, a lot of what you get is directly related to how much you are willing to empty your wallet. If there is one place to splurge a bit, it would be here. A big reason is weight: any rotating mass has to be lifted against gravity just like anywhere else on the bike but you also have to work to accelerate it around in a circle. "One ounce off the wheel is like one pound off the frame" is an old saying. Spending a little more on wheels to save a few ounces is worth tons more than the same money spent to save the same weight anywhere else on the bike. There is also aerodynamics to consider. Now you can go crazy and get ultra light climbing specific wheelsets with very few spokes and shallow carbon fiber rims or a very aero wheelset like carbon fiber deep dish rims or even a rear disc but that is going too far. For the motocross athlete that will train and maybe occasionally hit a race or two, going for the "middle of the road" may be the best advice. You can get a very light wheelset that will also be very durable and fairly aerodynamic. The Ksyrium line from Mavic is a good example of this type of wheelset.

Local Dealer vs. Internet Dealer
One final thing to contemplate is where to purchase your new bike. You can scour the internet and get a super raging deal for sure but there is a lot of value in purchasing form your local bicycle dealer. How many times have you been to your local motorcycle dealer for advice and information? Well it’s the same for your bicycle dealer. You may spend a tad more but your return on service can be immeasurable. Not only can the dealer help ensure that you get the right size frame, but they can also switch out other parts like stems, handlebars and saddles at the time of purchase to make sure the bike fits perfectly, oftentimes without any extra charge. An internet dealer is not going to do that. When something goes wrong on the bike the dealer will be there to guide you through the problem and make sure you use the correct tools and parts or they can do it for you. The internet dealer cannot provide services in this manner. The local dealer will always prefer to work on bikes that they sold you and understandably so. These are issues you will want to consider before making your final purchasing decision.

Now you are armed with the basic information necessary to make an intelligent bicycle purchase. A carefully chosen ride will not only provide valuable cardiovascular training but also another avenue of enjoyment, camaraderie, and learning. You are delving into a whole other sport with all its own techniques, goals, social quirks, and mechanical issues just like motocross! Now get out on the road and enjoy!

Seiji Ishii is the head coach of www.coachseiji.com . Coachseiji.com provides fitness coaching services to motorsport and endurance sport athletes. Coach Seiji works with pros like Team Solitaire’s Ryan Clark and elite amateurs like Monster Energy/Kawasaki Xtreme Team Green’s Hunter Hewitt and PJ Larsen. You can contact Seiji at seiji@coachseiji.com .   That's it for now. Until next time, good luck with your training and, as always, VT can be reached anytime at crytset@comcast.net .  In addition, be sure and check out the Racer X Virtual Trainer archive section , your complete one-stop information zone for motocross fitness.