The 987 is a low profile brake that has cold forged arms made of aluminum alloy. The arms are anodized in five colors, Blue, Black, Ti Grey, Lavender, or Silver.
Mechanical explanation of the 987. Each arm's internal tension spring is accessible, replaceable, and adjustable. One end of the spring fits into a hole on the arm, the other end of the spring fits into a cadmium plated metal nut. The bottom of this nut is hex shaped with a 3.5mm rise, so a 13mm cone wrench can be used to adjust the spring tension. When mounted on the bike, turning it clockwise tightens the spring. A Black plastic shroud covers the spring assembly leaving just the hex bottom visible.
The brake arm revolves around a machined steel bushing inserted into a brass sleeve inside the brake arm. So the aluminum arm has a brass inner sleeve, which has a separate steel bushing that the mounting stud passes through. The brake pads are mounted on the rear of the arm. Dia-Compe uses four steel parts to hold and pivot the brake pad. The steel parts are the pad holder, the washer that is the base for the pad to rest against, a small flat washer and a Black painted, conically shaped steel nut. This steel nut uses a recessed 6mm hex fitting to tighten it from the front. Each of the cadmium plated steel pad holders weighs 8.5 grams. We found any of the SRP Ti pad holder (eyebolt) replacements worked in place of the original, but the short length, bulb shape (our part number 06-91-PH) did particularly well because the short threaded post didn't interfere with the 6mm wrench insertion into the conical nut as the nut was tightened. By coincidence they are also the lightest Ti replacements.
The 987 relies on a traditional cable carrier arrangement. Each 987 comes with a 270mm long straddle cable that has two lead anchors on one end. A 7mm barrel shaped lead piece fits into the top of the left arm, the second lead anchor is to make a finger hold to quick release open the brake. The other end of the cable is bolted down, at the rear, to the top of the right arm. The cable fastening bolt is cadmium plated steel, with a 5mm hex fitting in its head. It's threaded has 6mm by 1mm pitched threads and is 10mm long with a 3.5 grams weight. The straddle wire is carried by a carrier stamped from aluminum plate. The Black carrier uses a "keyed" (fits in just one way) steel bolt with a hole through it. The brake cable inner wire passes through the hole and a Black aluminum nut tightens the bolt and two spacing washers to securely hold the inner wire. End of Mechanical.
The 987 comes with two Black steel washers and two Black steel mushroom head mounting bolts. These bolts have 6mm by 1mm threads, are 13mm long and weigh 5.5 grams. The steel washer covers the pivot axle beneath the mounting bolt. The brake pads are a one-piece molded design using steel re-enforcement and a non-threaded aluminum mounting post. The pad is 53mm long by 15.3mm high with a rim contact surface that is 50mm by 10mm in a slightly arched shape to mimic the shape of the rim. The pads are Black except in the case of the Blue or Lavender 987 where they are Grey. We found the Black pad had an A/92 hardness and the Grey measured to an A/91. The brake pads weighed 36 grams per pair.
We found the 987 cantilever had a Bike-Pro brake profile measurement of 51mm. The 987 can be used as either a front or a rear and weighs 155.5 grams. To this add 15.5 grams for the straddle cable and carrier, and 13 grams for the mounting bolts and washers for a total weight of 184 grams. Specify color. Made in Japan.
Color-B-BK-L-S-T $ Price in Catalog
The 986, like the 987 has cold forged arms, in this case available only in three colors, Black, Ti Grey or Silver. You might notice that it has stylistic similarity to the Ritchey Logic cantilever, this is because Dia-Compe makes the Ritchey brake. The two brakes were developed simultaneously and released on the market at about the same time.
Mechanical explanation of the 986. Many of the parts used in making the 987 are also used on the 986. In some ways it will be easier to point you back to the above writing where the part or principle is the same. First, the internal tension springs are again accessible, replaceable and adjustable. This is because are the parts related to the spring system, plastic shroud, cadmium plated nut, the spring and the inner machined steel bushing are exactly the same as those used in the 987. Therefore a 13mm cone wrench will again make tension adjustments on either arm. As it happens, the Dia-Compe 986 uses the same pieces to hold the brake pad. There is an almost imperceptible difference in the conical nut that is not functional. The conical nut and the aluminum washer are Silver in color on this brake rather than Black, but they are the same. All the SRP Ti pad holders will work, but exactly like the 987 the short length, bulb shaped (our part number 06-91-PH) did particularly well for the same reasons.
The 986 uses the same cable carrier and straddle wire as the 987. For the 986 though, the aluminum plate and nut on the carrier are Silver instead of Black. The straddle wire again cinches down at the top of the right arm, using the same cadmium plated bolt found in the 987. The Silver color carries over into the mounting bolts and washers. Though the same as the 987 these are also Silver. End of Mechanical.
The 986 comes with Grey brake pads, the same ones sold on the 987. So the largest difference between these brakes will be the difference in the weight of the arms, since most everything else is identical. We found the 986 had a Bike-Pro brake profile measurement of 61mm. The 986 can be used as a front or a rear and weighs 156.5 grams. To this add 15.5 grams for the straddle cable and carrier, and 12.5 grams for the for the mounting bolts and washers bringing the total weight to 184.5 grams. Just a 1/2 gram heavier than the 987!! Made in Japan
Color - BK-S-T $ Price in Catalog