Oddjob
Merry fucking Xmas to you assholes
Maybe I should have started a new thread so you could all tell me to use the search function
We have to haze the newbies somehow...
"Brake jack" - an explanation.
- Thread starter S.
- Start date
We have to haze the newbies somehow...
S.
ex offender
Maybe I should have started a new thread so you could all tell me to use the search function
So to be "fully active..." you need three things?
-Two of the links which are perfectly parallel with one another all throughout the travel.
-a CC which is fixed with respect to at least on of the pivots.
-an IC distance which is infinitely far away (in front or in back of the axle).
???
If by "fully active" you mean no brake input to the suspension whatsoever, you'd need two parallel links (which give you the infinitely far away IC) and a vertical axle path. But that's assuming you want no brake input to the suspension...
bromontryder
Cannon Fodder
S.
ex offender
No - IC height also has a big effect like I said. Position of the centre of mass, wheelbase, and shock rate all come into play if you want to do a quantitative analysis.
Any low pivot bike with a parallelogram floater is going to be pretty close, but the reality is that there is a limit to what you can actually feel anyway, let alone what is actually detrimental to the bike's performance, so it doesn't really matter all that much anyway if it's not "perfect". Besides that, what's 100% neutral is not necessarily the "best" setup - Barel for example had that crossover floater that gave the bike an insane amount of squat because it helped keep the bike level when braking hard.
Non-reacting suspension to breaking
Form the first post:
- It is possible, although not necessarily desirable, to have a suspension setup which does not have a squatting or extending tendency under brakes (at a given instant or instances). This, I believe, should be kept separate in terminology, from suspension extension due to weight shift. It is fairly easy to understand that if the brake torque/axle reaction force doesn’t exhibit a compressive or extensive force/moment on the suspension AT ALL, then under any braking the suspension will extend due to weight shifting forwards. For this reason, it may be useful to have some amount of pro-squat (tendency to compress). I know of no situations where it is helpful to have anti-squat (a net extension force, in other words actual “brake jack”) under brakes, as this only exaggerates the forwards weight transfer.
Question:
Wouldn't it be better to consider a system where the pro-squat fully counteract weight shift as a 100% non-reacting suspension to braking? I think this is what anti-squat calculation is about (use in bike suspension marketing for the DW-Link)
This system will not, when the rear brake is applied, create any add in vertical forces to the rider thus it will not create any vertical acceleration on him.
Wouldn't this system be the best compromise for having good bracking caracteristics?
Form the first post:
- It is possible, although not necessarily desirable, to have a suspension setup which does not have a squatting or extending tendency under brakes (at a given instant or instances). This, I believe, should be kept separate in terminology, from suspension extension due to weight shift. It is fairly easy to understand that if the brake torque/axle reaction force doesn’t exhibit a compressive or extensive force/moment on the suspension AT ALL, then under any braking the suspension will extend due to weight shifting forwards. For this reason, it may be useful to have some amount of pro-squat (tendency to compress). I know of no situations where it is helpful to have anti-squat (a net extension force, in other words actual “brake jack”) under brakes, as this only exaggerates the forwards weight transfer.
Question:
Wouldn't it be better to consider a system where the pro-squat fully counteract weight shift as a 100% non-reacting suspension to braking? I think this is what anti-squat calculation is about (use in bike suspension marketing for the DW-Link)
This system will not, when the rear brake is applied, create any add in vertical forces to the rider thus it will not create any vertical acceleration on him.
Wouldn't this system be the best compromise for having good bracking caracteristics?
Last edited:
SouthYarraSage
Likes Dirt
Not sure you wouldn't want a bit of extension - having your bottom bracket drop 3 or so inches on hard braking could be a little disconcerting...?