The front brake calipers were manufactured by Lockheed and used two pistons per caliper. The brake caliper is the assembly which houses the brake pads and pistons. Bianchi pioneered the front-wheel caliper brake. Disc brakes consist of a rotor and caliper at each wheel. These rims cannot be used with caliper rim brakes. But they are almost ubiquitous on road bikes, particularly the dual-pivot side-pull caliper brake. Thus caliper brakes are rarely found on modern mountain bikes. A sticking front caliper may also cause steering vibration. A clamp force sensor is a relatively expensive component in an EMB caliper. Brembo M50 is standard front caliper for the S model and Pikes Peak. The gauge is then removed and measured with a caliper or micrometer. This situation can be avoided by embedding a clamp force sensor deep within the caliper. This is a greater problem with a caliper incorporating a wheel, which lends mechanical advantage. Measuring equipment such as a Vernier caliper is often essential. Instead, it is measured and specified separately as its caliper.