There are many different ways to build or set up a cyclocross bike. Most are related to personal preference, but no matter how a bike is set up, the basic principles that should be adhered to are that the bike should be reliable, light, and simple. The order in which you prioritize these things depends on how fast you are, how serious you are, or how rich you are. For many, reliability is infinitely more important than light weight, because there's nothing slower than a broken bike. For others, there may be a mechanic and two more bikes available in the pits, so while reliability is still crucial, light weight might move up a degree.
More so than other disciplines, 'cross riders tend to be fanatical about their equipment, hoarding caches of dated components that often work better than anything currently available. We'll go through each aspect of the bike piece by piece and talk about what works best and why, and how things have changed over the years. In the past two articles, we've talked about the big things like how to fit your bike, and how to select wheels and tires. In this article, we'll tie together all the little details to make the picture complete, like shifters, brakes, and drivetrain.
There're no two ways about it; integrated brake/shift levers like SRAM DoubleTap and STI are by far the fastest, easiest way to shift a 'cross bike. You don't have to take your hands off the hoods, they shift with a small, precise movement, and the levers themselves are big and comfortable. But they have their drawbacks. For starters, they are expensive. 'Cross is hard on your equipment, which is a concern if you're paying for it. There was a time when I was paying for you parts, and I prefered the light weight, simplicity, and reliability of bar-ends over integrated shifters. Bar-ends last forever, and if you're buying your equipment, that's important. If you race in conditions that aren't going to be hard on your equipment, or money is less of an issue, integrated shifter are the way to go.
These days, integrated shifters are ubiquitous, more affordable, and more reliable, and really the choice has moved on to electronic shifting over traditional cable. Certainly, electronic shifting removes a hassle of replacing cables, while adding the hassle of remembering to charge a battery. And as we've seen, electronic front derailleurs for 'cross aren't quite perfected yet, with lots of dropped and jammed chains that can't simply be shifted back on to the big ring while pedaling. If you value simplicity and affordablity, cable shifting will always work. Electronic shifting is in all of our futures, however, and is an inevitability. It really is just a matter of when you decide you're ready to make the switch, no pun intended.
Here, the debate in previous years would have been between a traditional, wide cantilever, a low-profile cantilver, or v-brakes. Now, the question has moved to cantis v. discs, and hydro v. cable. If you're sticking with cantilivers, the trade off is always between brake power and brake arm movement and pad clearance. The more pad clearnace you have, the more the brake arm has to move, andt the spongier and less powerful the brake becomes. Traditional wide cantis like a TRP EuroX or Avid Shorty set to the wide position fall into that category. In the middle are more powerful, low-profile brakes like the TRP RevoX (which is my personal preference) or the Avid's set to the narrow position. V-brakes like the TRP CX 8.4 are incredibly powerful, almost too much for me, and on par with any disc brake I've used, but have the least amount of pad clearance, and are most likely to get clogged in heavy mud, which is, ironically, when you tend to need the most powerful braking. Your choice within these options should be based on your hand strength and your typical racing conditions. Personally, low-profile cantis provide enough braking power and pad clearance for me, and are the lightest set up available.
Disc brakes are here to stay, and again like electronic shifting, it's simply a matter of time before it becomes the standard we're all on. The current main drawbacks are still weight and pad wear in mud, but as those factors continue to be addressed, the reasons for not going to discs are disappearing. Another consideration for many people is compatibility between bikes, since many of us are sharing rim brake wheels between our road bikes and 'cross bikes. But again, as disc brakes start to show up on the road, and quick release v. thru-axle standards start to settle down, it will make sense to begin to replace personal wheel inventories with new technology.
The advantages to discs are not just increased stopping power, but increase control of that power. Being able to brake with only one finger instead of two may sound like a small thing, but being able to dedicate an extra finger to steering your bike through a turn, rather than to braking, can make a big difference in bike handling ability. Add the benefit of hydraulic braking systems and the automatic recentering and adjustment that happens as pads wear, and you have, unquestionably, the best braking system available. Of course, hydro introduces another level of complexity to the system, and it's still easier to change a cable than it is to bleed a brake. But changing cables is something you have to do regularly during a 'cross season, sometimes weekly, while it's possible to set a hydro system up once at the start of the season and not touch it again for months. Eventually, we will all be on hydraulic brakes, for road as well. Another inevitability.
Here's an example of how the more thigns change, the more they stay the same. Single-ring set ups are as old as 'cross, and were always done with a single chainring and two chainguards on either side. Chainguards were often simply larger chainrings with the teeth ground off of them. As courses got faster and cranks (and shifters) improved in the late 1990s, particularly with the introduction of Shimano's 2-piece crank and narrower Q-factor, single-ring set ups went out of style, only to make a comeback recently with the introduction of narrow/wide chainrings, clutch rear derailleurs, and wide cassette ranges, perfected by SRAM with it's 1X system.
If you decide to go with a single ring, the first step is to figure out what size chainring to use. You could go as small as a 38 or as large as a 46, with 42 being the standard. I've done an entire elite season on a 39 x 12 as my biggest gear, so don't be afraid go small on the single ring, especially if you have an 11 in back. It's hard to make general gearing recommendations because riders vary so much in terms of weight and power, but for me at 155 lbs, a 40 X 28 will get me over most hills in 'cross race, and 40 X 11 will handle any start or finish sprint. There is a point where having a really small gear offers no benefit, as it would be faster to run, but where that point is will be very personal. The benefit of a single-ring set up are again primarily simplicity, with no front derailleur or shifter to worry about, or to break.
If you're using two chainrings, your little ring could be anywhere from 34 to a 39, and your big ring could be a 44 though a 48. I find an 8-tooth difference to be ideal for shifting and for speed changes, and prefer a 44/36.
Personally, I'm currently using a double-ring set up on my primary training bike, and single-ring set ups on my two race bikes. I realize that sounds like a luxury to most people, and indeed, it is. I prefer the double-ring set up on my training bike so that I can use it for both road and 'cross training and have a wider range of gears and finer gear ratio selection. I need a bike I motorpace with, and do a slow, muddy 'cross workout on. But in the races, a single-ring set up gives me all the gears I need, with a reliable and simple approach.
If you only have one bike and can rely on your road bike for road training, then a single-ring set up is a great way to go. If you're 'cross bike is you only bike and you plan to use it for road and 'cross, a double is the best choice.
For cassettes, my preference is an 11 x 28, whether I'm on a single or double up front. With a single-chainring set up, you'll find yourself using both ends of the cogset, whereas with a double ring you'll stay more in the median. Some people prefer a 32 as their smallest cassette, and if you're running a single it may be necessary, but again, there's a point where you might be better served running.
With the information from this series of set up articles, you should have all the information you need to make educated equipment choices for cyclocross. Hopefully, I've demystified some of the lore and legend associated with 'cross, and helped make the sport more accessible for those of you getting started, and even those of you with some experience.