Skip to main content
Bicycles

Return to Answer

added 386 characters in body
Source Link
Nathan Knutson
Nathan Knutson
  • 86.5k
  • 4
  • 95
  • 222

Cantilever brake studs are a standard dimension, and there are two different ways that cantilever brakes utilize them:

  • The frame stud is a dynamic surface. Each brake arm has a brass bushing running through that's just a little shorter than the stud is long, such that 0.1-0.3mm-ish of the stud extends past the top. The mounting bolt then tightens down the washer against the end of the stud. Any torque imparted in this design is very minimal. Yes the arm might contact the washer but the washer is not pressing down on it in any way. This kind of brake arm needs the mounting bolts torqued very low (2 ft-lbs appears on some torque charts) and should have threadlocker applied. This type is more common and is on the brakes you have.
  • The frame stud is not a dynamic surface. The arm parts extend past the top of it. You tighten the bolt and washer down on it directly (6 ft-lbs/8 Nm or so). The pivot is contained in other parts in the brake, which allows tighter tolerance control and control over the material and finish of both parts, not just the bushing. Many but not all higher-end cantis since the 90s use this design, as well as some mid-range models. There is not a consensus name for this type; I usually refer to is "integral pivot." Some examples are the Tektro Oryx and all the Paul cantilevers. Some brakes of this sort are particular about the size or shape of the bolt head, for example the Paul design where it nestles inside the spring tension adjuster, and others are indiscriminate about it.

For the design you have, where the stud is the pivot, what's really important and where things can go wrong with picking hardware is that the washer needs to fully cover the tip of the stud as best as possible. If the hole is a little too big, what can happen is that the washer gets deformed when you tighten it and start to contact the arm when it shouldn't be, which binds the brake up. Another piece of this is that some studs are nice and machined flat on top, which makes this problem less likely, and some are more rounded, which means the actual amount of contact area with the washer is very small at the best of times. All that said, a proper M6 good quality grade 8 or stainless washer from the hardware store and the matching M6 bolt should usually be fine, plus medium-strength threadlocker. For length, the manufacturer-supplied ones are anywhere from 16 to 24mm. Also if you have a common M6 disc caliper mounting bolt and washer around in the 16mm-ish length, that's fine too, it's basically the same thing as many manufacturer-supplied mounting bolts. Cantilever mounting bolts are visually prominent so they're usually domed and relatively pretty, but that's all that differentiates them from other M6 bolts with 5mm allen heads on bikes.

Cantilever brake studs are a standard dimension, and there are two different ways that cantilever brakes utilize them:

  • The frame stud is a dynamic surface. Each brake arm has a brass bushing running through that's just a little shorter than the stud is long, such that 0.1-0.3mm-ish of the stud extends past the top. The mounting bolt then tightens down the washer against the end of the stud. Any torque imparted in this design is very minimal. Yes the arm might contact the washer but the washer is not pressing down on it in any way. This kind of brake arm needs the mounting bolts torqued very low (2 ft-lbs appears on some torque charts) and should have threadlocker applied. This type is more common and is on the brakes you have.
  • The frame stud is not a dynamic surface. The arm parts extend past the top of it. You tighten the bolt and washer down on it directly (6 ft-lbs/8 Nm or so). The pivot is contained in other parts in the brake, which allows tighter tolerance control and control over the material and finish of both parts, not just the bushing. Many but not all higher-end cantis since the 90s use this design.

For the design you have, where the stud is the pivot, what's really important and where things can go wrong with picking hardware is that the washer needs to fully cover the tip of the stud as best as possible. If the hole is a little too big, what can happen is that the washer gets deformed when you tighten it and start to contact the arm when it shouldn't be, which binds the brake up. Another piece of this is that some studs are nice and machined flat on top, which makes this problem less likely, and some are more rounded, which means the actual amount of contact area with the washer is very small at the best of times. All that said, a proper M6 good quality grade 8 or stainless washer from the hardware store and the matching M6 bolt should usually be fine, plus medium-strength threadlocker. For length, the manufacturer-supplied ones are anywhere from 16 to 24mm. Also if you have a common M6 disc caliper mounting bolt and washer around in the 16mm-ish length, that's fine too, it's basically the same thing as many manufacturer-supplied mounting bolts. Cantilever mounting bolts are visually prominent so they're usually domed and relatively pretty, but that's all that differentiates them from other M6 bolts with 5mm allen heads on bikes.

Cantilever brake studs are a standard dimension, and there are two different ways that cantilever brakes utilize them:

  • The frame stud is a dynamic surface. Each brake arm has a brass bushing running through that's just a little shorter than the stud is long, such that 0.1-0.3mm-ish of the stud extends past the top. The mounting bolt then tightens down the washer against the end of the stud. Any torque imparted in this design is very minimal. Yes the arm might contact the washer but the washer is not pressing down on it in any way. This kind of brake arm needs the mounting bolts torqued very low (2 ft-lbs appears on some torque charts) and should have threadlocker applied. This type is more common and is on the brakes you have.
  • The frame stud is not a dynamic surface. The arm parts extend past the top of it. You tighten the bolt and washer down on it directly (6 ft-lbs/8 Nm or so). The pivot is contained in other parts in the brake, which allows tighter tolerance control and control over the material and finish of both parts, not just the bushing. Many but not all higher-end cantis since the 90s use this design, as well as some mid-range models. There is not a consensus name for this type; I usually refer to is "integral pivot." Some examples are the Tektro Oryx and all the Paul cantilevers. Some brakes of this sort are particular about the size or shape of the bolt head, for example the Paul design where it nestles inside the spring tension adjuster, and others are indiscriminate about it.

For the design you have, where the stud is the pivot, what's really important and where things can go wrong with picking hardware is that the washer needs to fully cover the tip of the stud as best as possible. If the hole is a little too big, what can happen is that the washer gets deformed when you tighten it and start to contact the arm when it shouldn't be, which binds the brake up. Another piece of this is that some studs are nice and machined flat on top, which makes this problem less likely, and some are more rounded, which means the actual amount of contact area with the washer is very small at the best of times. All that said, a proper M6 good quality grade 8 or stainless washer from the hardware store and the matching M6 bolt should usually be fine, plus medium-strength threadlocker. For length, the manufacturer-supplied ones are anywhere from 16 to 24mm. Also if you have a common M6 disc caliper mounting bolt and washer around in the 16mm-ish length, that's fine too, it's basically the same thing as many manufacturer-supplied mounting bolts. Cantilever mounting bolts are visually prominent so they're usually domed and relatively pretty, but that's all that differentiates them from other M6 bolts with 5mm allen heads on bikes.

Source Link
Nathan Knutson
Nathan Knutson
  • 86.5k
  • 4
  • 95
  • 222

Cantilever brake studs are a standard dimension, and there are two different ways that cantilever brakes utilize them:

  • The frame stud is a dynamic surface. Each brake arm has a brass bushing running through that's just a little shorter than the stud is long, such that 0.1-0.3mm-ish of the stud extends past the top. The mounting bolt then tightens down the washer against the end of the stud. Any torque imparted in this design is very minimal. Yes the arm might contact the washer but the washer is not pressing down on it in any way. This kind of brake arm needs the mounting bolts torqued very low (2 ft-lbs appears on some torque charts) and should have threadlocker applied. This type is more common and is on the brakes you have.
  • The frame stud is not a dynamic surface. The arm parts extend past the top of it. You tighten the bolt and washer down on it directly (6 ft-lbs/8 Nm or so). The pivot is contained in other parts in the brake, which allows tighter tolerance control and control over the material and finish of both parts, not just the bushing. Many but not all higher-end cantis since the 90s use this design.

For the design you have, where the stud is the pivot, what's really important and where things can go wrong with picking hardware is that the washer needs to fully cover the tip of the stud as best as possible. If the hole is a little too big, what can happen is that the washer gets deformed when you tighten it and start to contact the arm when it shouldn't be, which binds the brake up. Another piece of this is that some studs are nice and machined flat on top, which makes this problem less likely, and some are more rounded, which means the actual amount of contact area with the washer is very small at the best of times. All that said, a proper M6 good quality grade 8 or stainless washer from the hardware store and the matching M6 bolt should usually be fine, plus medium-strength threadlocker. For length, the manufacturer-supplied ones are anywhere from 16 to 24mm. Also if you have a common M6 disc caliper mounting bolt and washer around in the 16mm-ish length, that's fine too, it's basically the same thing as many manufacturer-supplied mounting bolts. Cantilever mounting bolts are visually prominent so they're usually domed and relatively pretty, but that's all that differentiates them from other M6 bolts with 5mm allen heads on bikes.