IRD Rotary brake

The history of mountainbiking is filled with small companies that tried to make their mark by refining existing component designs, there are only a few companies that had the engineering know-how to design and fabricate their own unique parts. One of these companies was IRD or Interloc Racing Design.

IRD was founded by Rod Moses who partnered with Ray Baldwin to produce some of the most well engineered components to be found! Although they are probably most famous for the invention of the two-bolt seatpost, which until today is copied by a lot of companies, their brake designs is what i'm most interested in.

In the eighties and the beginning of the nineties the u-brake was used as an alternative over standard cantilever designs. The problem with cantilevers is that they pivot at the bottom end of the brake-arms and that they are mounted on the seatstays. Because the seatstays are longer and often thinner than the chainstays they will flex outwards resulting in lost perfomance. U-brakes are best mounted under the chainstays and that combined with a pivoting point in the middle of the brake-arms gives a lot less flex.

IRD came up with an ever better design. Although the pivot point and the brake pads are held in the same position as a standard u-brake, the way the power is delivered is just brilliant and powerful!

The photo above shows the mechanics of this brake. The cable that sticks out at the top of the brake wraps around the big wheel which is mounted to the right arm at top center. The other end of the cable is fixed on the big wheel on the other side of it's mounting point. The mounting point allows the big wheel to rotate. What happens is that when you pull the cable the big wheel will swing out to the left, pushing the top of both arms outwards and both brake pads together crushing the rim!