Buying Your First Cyclocross Bike
With the new hotness being cyclocross these days, it might be helpful for some to get some advice on buying your first ‘cross bike.
First, some rules.
- The content is targeted at road or mountain bike riders who are already riding regularly. Or, someone interested in upgrading their road bike and considering a cyclocross bike.
- If you want a to read about the interaction of cyclocross geometry on your road postion or some other equally dense fiction then go elsewhere.
- I’m talking complete bikes available at your Local Bike Shop coming in around USD $3,000 or less. No Empella/Ridley mentions because these are very well outside the norm in many ways.
- I’m talking specifically about cyclocross bikes with drop bars. I’m very glad there are flat bar multi-purpose bikes because it generally means more bike riders, but I’m not discussing these.
What’s different about a cyclocross bike versus a road bike? They have room for fatter tires, and more powerful cantilever brakes. You sit higher on a ‘cross bike because the bottom bracket is much higher than the equivalent road bike. Many accommodate fenders so one can ride in more varied weather without getting soaked by the tire spray. The ability to ride much more varied terrain is a big plus.
What’s the same about a cyclocross bike? For road riders, the geometry is very similar to the average road bike. You can very easily race a cyclocross bike in road events like time trials and criteriums. There is a slight weight and aerodynamic penalty, but that is not actually important in a Category 4/5 field.
Measure your current bike:
If your bike has a perfectly horizontal top tube, then measure the top tube from center-of-the seat-tube to center-of-the-head-tube. Mark the spot you measured on your seat tube.
If your bike has a sloping top tube, then measure from the center-of-the-head-tube to the center-of-the-seat-tube keeping your tape measure flat. mark the spot you measured to on your seat tube.
Measure from the center of the bottom bracket to the spot you marked on the seat tube.
Top Tube Spec.
For road riders, seek a ‘cross bike with a top tube length within 0 to -1 cm. You want to be more upright on a cross bike than a road bike, so a little shorter top tube is a benefit. Cross-country mountain bike riders will want to have a similar top tube length, gravity-riders will be much more stretched out.
Seat Tube Spec
The seat tube length needs some special consideration because the bottom bracket is much higher on a ‘cross bike. I recommend a seat tube specification ~1-2 cm shorter.
Mountain Bike Riders
Translating your seat tube length into a ‘cross bike is a bit more difficult because of the variations in mountain geometry. Subtracting 2cm from the length of the seat tube dimensions from above works for me on my cross-country oriented full-suspension bike.
Results
The end result should be a seat post that sticks out a 1-2 cm more than a traditional horizontal-top-tube road bike. Remember, the bottom bracket is much higher than a road bike. The effective standover height will resemble a road bike and the brand’s frame size will generally come in -2 cm smaller than a traditional horizontal-top-tube road bike. In pictures, it should look something like this .
I know there are other setups that end up looking like Todd Wells’ or Ryan Trebon’s, super-tall seatpost but I think those are outside cases specifically crafted for those racers and won’t translate very well when buying a retail bike.
Other details
Don’t get hung up on minor differences between bikes. Riding cyclocross is still a test to see how many Watts you can generate with bike handling technique a contributing factor. Cable routing, frame material or other details just don’t matter that much.
Some objective proof to discourage splitting hairs on equipment, Dan Timmerman (Richard Sachs) got a top-10 at nationals this year (2009) on an ‘old-fashioned’ steel ‘cross bike and David Frattini had some excellent results on a practically stock Fuji cyclocross bike.
Ride more!