The Fall of Discs: Trick your Avid BB7 brakes
Editor’s Note: Disc brakes are here for cyclocross in a big way. Nearly every manufacturer is offering at least one disc-ready frame and many of the sport’s heavyweights are adopting the technology for 2012-13. We’ve been proponents of disc technology for ’cross for years and over the coming weeks, VeloNews.com contributor Michael Robson will explore the burgeoning arena of ‘cross-specific disc brakes, from the new gear to tips on getting your disc set-up dialed.
It’s become pretty apparent that Avid’s 13-year-old design, the BB7 road caliper, will be the brake of choice this year in the new disc-heavy cyclocross market. The BB7’s simplicity, reliability and ease of setup set it apart from lighter cable-actuated calipers and even some of the hydraulic options currently available. After canvassing everyone from Tim Johnson (Cannondale-Cyclocrossworld.com) and Boulder Cycle Sport’s Brandon Dwight to the local Cat. 4 and Masters racers, if they’re going disc in 2012, they’re almost across the board on the BB7. Now, this all could change with a new product announcement from any one of the big component companies at Interbike next week, but it’s not clear that’s going to happen. For now, the BB7 is a solid performer and with a bit of tweaking and upgrading can be flat-out fantastic.
1. Get it right: Proper installation and setup are more critical for disc brakes than for cantilevers, because the tolerances are a lot lower and the calipers must be aligned and adjusted just right. The BB7 is incredibly easy to work with and the Caliper Positioning System (CPS) makes it possible to precisely align the caliper even if the mounting posts aren’t quite perfect.
Now, I’m not going to get into all the gory details of mounting the caliper — there are a couple of cheesy but highly instructive BB7 install videos on YouTube that will set you on your way. The objective of the game here is to have your calipers nicely aligned on the rotor so it can be dialed in with no rubbing. A handy tool to have at this point is a Torx T25 wrench; the inboard pad adjustment on the BB7 can be rotated by hand, but it’s way easier with the right tool. Once the caliper is mounted, it is easy to adjust brake feel at the lever by tweaking the pad position on the caliper. I personally don’t like the brake coming on early in the lever travel. I think there is more modulation control and smoother braking if the brakes start working about halfway through the travel of the brake lever.
2. True your rotors: Your rotors might arrive perfectly straight out of the box, if you’re lucky. But depending on your rotors and the interface to the hub, there will usually be a little bit of waviness when the wheel is spun. Here’s where Park Tool’s DT-2 Rotor Truing Fork is a worthy addition to your toolbox. When truing rotors, take it steady until you get the hang of it; it’s really easy to over-correct and make the rotor worse than when you started. Keep in mind that once you have a rotor perfect, it will only be matched to that particular hub. Changing rotors to another wheel will require you to repeat the process.
3. Rotor position: In ’cross, even more so than mountain biking, you might be changing and using different wheels regularly. It is important to make sure the rotors across each of your wheels are in the same position so you don’t have to re-align the caliper each time you change wheels. If you have all the same hubs, chances are everything will line up, but if not, you might need to space out your rotor position. Check the position of each rotor in relation to the caliper and use the most outboard for the caliper setting. Then space out the rotors on the other hubs to match. Wheels Manufacturing makes spacer washer kits and Syntace makes very handy universal ISO spacers that will get your rotor position right on.
4. Bed your brakes: The first thing you might notice if you are new to disc brakes is exactly how well they don’t work when you first ride them. This is because the pads need to be bedded to the rotors. This is best done on a small downhill. Roll forward and simply reef on the brakes hard for about 10 seconds. This will build up heat, but not too much. Wait a minute to allow the brakes to cool and do it again. Repeat this cycle 7-10 times and your brakes should be ready for action.
5. Lighten up: One of the only drawbacks of the BB7 is the weight (The new RSL version, available later this fall, solves this issue to a point). Titanium bolt kits are available for the BB7 and Formula makes titainium rotor bolt kits as well. Just brace yourself for the price. All told, these upgrades will only shave 20-25 grams per wheel, but with disc brake bikes gaining up to and sometimes beyond a pound over cantilever bikes, you might feel it’s worth it to chop weight where you can.
6. Pad selection: BB7 brakes come stock with steel-backed organic pads, but you can upgrade these to aluminum-backed organic pads or any number of aftermarket pads from Jagwire, Kool Stop and EBS, to name but a few. This is a whole story by itself, but the general rule is that organic pads are quiet and strong and wear faster while metallic pads are a bit noisier and longer wearing. Ask your local bike shop for its recommendation for local riding conditions.
With that, go out and enjoy your BB7 brakes. Until something dramatically different comes along, we’re going to be seeing a lot of them. For the record: I’m riding them, at least for now.