Compass Centerpull Brake Specs

Compass Centerpull Brake Specs

The new Compass centerpull brakes have been very well received. Numerous builders have asked for the complete specifications for the brakes, since many riders plan to use them on their new bikes. We sold so many of the centerpull braze-ons that we are currently out of stock of these pivots, but another shipment is expected next week.
We recommend that builder have the brakes on hand when they build the bike, so that they can make sure everything fits just right. We have the specifications available online as part of the instructions for the brakes. This also allows riders to check whether the brakes will fit their existing bikes.
The specifications include detailed drawings that allow builders to get the clearances just right for bikes with 650B x 42 mm tires and full fenders. These measurements are the result of a year’s work: measurements were taken, calculations performed, CAD drawings created, prototypes built… We wanted the entire system of fork/tire/fender/brake/rack to be right, once and for all. These specs will be useful for builders who are not using Compass brakes on their current project, since they show the optimized clearances for tires and fenders.
The Compass CP1 rack is specifically designed to go with the Compass brakes. (The rack only works with centerpull brakes.) The rack is based on a René Herse rack that combines elegance, light weight and rigidity.
It is important that the brake pivots are located at the right height, otherwise the rack will sit too high or too low above the fender. The instructions for the brakes include all measurements a builder needs to build a bike with our brakes and our rack.
The rack and brakes also work for other configurations in addition to 650B wheels and 42 mm tires. For other wheel diameters, the dimensions remain the same in relation to the top of the tire – the builders simply adjusts the measurements for the different outer diameter of the wheel.
It’s been a lot of work to get to this point, but when we rode these brakes during pre-production testing (above), we realized that it was totally worth the effort. The absolute braking power of the Compass brake is great, and the modulation is superb. This gave us great confidence descending challenging mountain roads at speed. As always, the goal is to have more fun on our bikes!
Click here to download the complete instructions.
Click here for more information about the centerpull brakes.

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Comments (7)

  • Dan Christopherson

    Very impressive, Jan. Stop by the next time you’re on Orcas Island.
    Dan Christopherson, Wildlife Cycles

    January 29, 2015 at 7:23 am
  • Eddie J.

    Hi Jan-
    Would you recommend these brakes for a CX build or stick with Cantis? Not in the disc camp at this time.

    January 29, 2015 at 9:01 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Excellent question… Common wisdom is that cyclcross bikes use cantis for extra mud clearance. Yet in the 1960s, many ‘cross racers used centerpulls. I haven’t tried centerpulls in a muddy cross race, but I figure that the mud will get stuck on the seatstay bridge and fork crown. As long as the brakes aren’t more constricting than those “hard points”, it may work well. And you’d eliminate the fork judder.
      I have been tempted to build a ‘cross bike with an ultralight steel frame and centerpulls, but in the end, I like my Alan so much that I am willing to live with the fork judder at low speeds.

      January 29, 2015 at 9:07 pm
  • William M. deRosset

    The first-generation Alan cyclocross machines were designed for bolt-on centerpulls.
    I found that riding my road sport (superlight steel frame; medium reach dual-pivot brakes; cyclocross tubulars; road-going geometry) that the rear brake did pack in on thick mud courses, depending on the mud, and it was difficult/slow to clear. The fork packed in at about the same rate as the dedicated CXers.
    However, the dedicated CX bikes were packing up as well at the same spot–seatstay bridge. They were faster to clean out, though, without the brake hardware complicating mud removal.
    A brazed-on centerpull would have more clearance. I don’t think a bolt-on centerpull would buy you much there.
    Sandy/dry/really wet mud was fine.
    William M. deRosset
    Fort Collins, CO

    January 30, 2015 at 9:59 am
  • Michael

    Why not cantis for maximum clearance?

    January 30, 2015 at 8:48 pm
    • Jan Heine, Editor, Bicycle Quarterly

      Cantis are mounted on an unsupported portion of the fork blades. When you brake hard, they twist the fork blades. That changes the toe-in of the brake pads, and leads to inconsistent braking. So the modulation of cantis often is poor. Centerpulls are mounted near the fork crown, so the fork blades don’t twist as you brake. Braking action is very linear, and modulation is excellent.

      January 31, 2015 at 4:47 am
  • Jimmy

    Seems like the optimal solution for rim-brake CX mud clearance would be to use a linear pull brake. The frame/fork is then free to be designed with the crown and bridges well away from the tire. Canti brakes would give similar design freedom. And for both of those brakes, a simple reinforcing arch (like the CNC aluminum ones from early MTB days) could be used to help with blade twist.
    That first drawing is attractive. Removing the balloons would make a nice t-shirt design.

    February 2, 2015 at 11:57 am

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