Timeline for Why dual pivot brakes, not longer brake arms?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Apr 20, 2021 at 3:21 | comment | added | Criggie♦ | @KonstantinShemyak I suspect it is because the pivot is (approx) above the brake pad then the arm below the pivot and therefore the pad is moving sideways, whereas an older single pivot both the arm and the pad have some "downward" component to their movement path, meaning the pad hits the rim at an angle, giving a "sum of vectors" result of less braking force applied to rim. | |
| Apr 19, 2021 at 7:48 | comment | added | Michael | @KonstantinShemyak: I’m not sure but I think in dual pivot designs it’s possible to adjust the spring tension of both arms independently, thus making sure that both brake pads have the same distance to the rim and hit the rim at the same time. | |
| Apr 19, 2021 at 6:43 | comment | added | Konstantin Shemyak | @Michael I accept the point about longer arms sticking aside! But I don't seee how does dual-pivot design allow the pads to be closer to the rim. | |
| Apr 19, 2021 at 6:36 | comment | added | Michael | @KonstantinShemyak: A longer arm would have to stick out sideways which would look bad, increase drag, increase the risk of it getting caught on something etc. You’d also have to position the brake pads much more carefully (which is apparently easier with dual pivot designs, allowing them to be closer to the rims). | |
| Apr 19, 2021 at 3:56 | comment | added | cmaster - reinstate monica | @Pisco Sorry, I misread the article. I've deleted my erroneous comment now. Thanks for correcting me. | |
| Apr 18, 2021 at 23:27 | comment | added | Pisco | @cmaster-reinstatemonica I don’t see where that article says that dual pivot side pulls exert a net sideways force on the rim. It seems to me that the centering screw not only communicates position between the arms but also transfers force from the arm with the cable fixing bolt, to the arm with the housing stop. presumably designers could position it between the pivots such that the pads move with the same speed and force, no? | |
| Apr 18, 2021 at 20:12 | comment | added | Konstantin Shemyak | Yes, dual pivot design creates a longer arm. So, I'm asking what is the technical reason (if any) not to just make longer arms without introducing the second pivot. | |
| Apr 18, 2021 at 20:05 | history | edited | Michael | CC BY-SA 4.0 |
added 188 characters in body
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| Apr 18, 2021 at 19:59 | history | answered | Michael | CC BY-SA 4.0 |