XTR pads touching rotor

[AndreZA]

Here's a spanner in the works. On my first Raleigh I had Avid Juicy 3 brakes. At about 28-30km/h and riding on smooth hardpack or tar you could hear the discs scraping the pads. But only at those speeds. I then discovered the it was the tyres at a certain pressure. The tread design would cause a vibration that you could feel even when sitting. Lower the pressure and it was fine.

[Reghard111]

Just keep it above 30 then Mampara!!!

[manbearpig]

Here's a spanner in the works. On my first Raleigh I had Avid Juicy 3 brakes. At about 28-30km/h and riding on smooth hardpack or tar you could hear the discs scraping the pads. But only at those speeds. I then discovered the it was the tyres at a certain pressure. The tread design would cause a vibration that you could feel even when sitting. Lower the pressure and it was fine.

Fascinating. Today isn't a waste, I learned something new 

[Johan Bornman]

OK there are obviously two schools of thought here. Contrary to what some may believe the piston does not SLIDE in and out on the surface of the O-ring during braking. The piston and the Oring surfaces stay in the same position relative to each other. Only the FLEX in the rubber seal (o ring) allows the piston to move forward and back. The only time the piston slides along the O-ring is when it needs to move forward to make up for brake pad wear. This happens because the amount of outward movement the piston needs to make up for brake pad wear exceeds the amount of flex the o ring allows for and therefore the piston will slide past its previous seating point on the o ring. As for the "elasticity of fluid" the whole point of brake fluid is that it cannot be compressed therefore it has zero elasticity. We could use water in our braking systems if it didn't have such a low boiling point and the nasty tendency to rust things.

If anyone out there is checking the patent on the flex of rubber see if there is a patent on the cushioning effect of air in tyres while you're at it. We may all find ourselves in court soon. As I said before this is my humble opinion but feel free to pm me if you would like to ask me with what experience I allow myself to make these deductions.

 

I feel like one of those okes in a wheelchair where everyone talks to the pusher, not the person.

 

Anyway, I can't find anyone who claimed that the piston slides past the O-ring during braking. I think that is well understood. However, I made the point that the retracting action changes with age, condition and lubrication. There are times when the piston slides - new pads, accidental activation when the wheel is out, etc etc. The discussion was also about making it slide back to give clearance. This will require a good piston and O-ring health.

 

The point you missed was whether the action you talk about was by design or as I said, by fluke. If it was by design, someone would have designed it that way and then most likely patented the design. USPatent.gov is a wealth of information on such matters. My guess was that it wasn't claimed by anybody. I looked and didn't find anything.

 

I didn't say there would be a patent on rubber flex, I spoke about a pantent for piston retraction using rubber flex.  There is a difference.

 

And by the way, fluid is compressible. At school they wrongly teach you that fluid is incompressible, as is solids. That is not the case. It is much less compressible than gas, but still compressible.

 

 

 

 

 

[Reghard111]

So when you wipe your bum and your ass cheeks seperate then this is by design? A patent by the the toiletpaper manufacterer?

I'd say its just fluke....

[techguy]

By your comments Manbearpig I assume you are a qualified motor vehicle mechanic with a number of years experience as I am...so you and I can understand the design of these things...

[Reghard111]

Qualified bwahaha.....Manbearpig is only qualified as a Babervis expert!