Disc brakes (modeling)

To model disc brakes in BikeCAD, open the Brakes dialog box. If your current design uses rim brakes, you'll probably want to remove them by unchecking the include buttons on the front and rear rim brake tabs.

Moving to the Disc tab, we can check the Include boxes for both front and rear disc brakes to enable disc brakes in our design.

If we look at the front disc brake, we can see that a standard disc brake has been chosen. It's a 160mm rotor paired with an International Standard disc brake tab. An I.S. type disc tab requires an adaptor to connect the disc brake to the tab, and BikeCAD has included one for us here. The dimensions for the disc brake, the rotor, the adaptor and the tabs are all greyed out because this brake has been chosen from our library of standard parts. The one dimension field that remains accessible to us is the ∠1 field. We can still change this value because even though we expect all these components to be fixed in position relative to each other, we still want to be able to play with the angle of the entire assembly by varying the angle at which we attach our disc tab to the fork. Of course, since this particular fork is probably a commercially available suspension fork, it is not the best example of a fork we'd be welding a disc tab to. In many cases, a commercially available fork will come with post mounts which allow the brake to be mounted directly to the fork without the use of an adaptor. We can select this type of brake from our library of parts as well. It should be mentioned that a fork equipped with post mount brakes won't necessarily require an adaptor. However, adaptors may still be needed to accommodate different sized rotors. To further clarify the difference between these two options, I'll turn off the display of the brakes and we can compare the posts that are associated with a post mount disc brake and the tabs that are associated with an I.S. style disc brake.

Moving to the rear, we have the same options available here. If we use the Custom option, we can fully control all aspects of our disc brake system. If we stick with our library of standard brakes, the one dimension we will still need to consider is ∠1. ∠1 will allow us to position our brake in a range of positions behind the seat stay. If we change ∠1 to a smaller angle, the brake will move in front of the seat stay and BikeCAD will automatically recognize that the disc tabs must be mounted to the chain stays instead of the seat stays.

If we happen to switch to sliding rear dropouts, BikeCAD will automatically integrate the disc tab with the sliding part of the rear dropout so that the brake will always remain in position relative to the rotor.