Locking hydraulic disk brake

[JeffD]

When I took off my front wheel I pulled the front brakes by accident and they locked as there was no wheel in place. I took my bike to my local bike shop and they sorted it out.

 

Then while packing up after the Lost City race yesterday like an idiot I did it again

 

How can I fix it myself without damaging the brakes and can someone please explain the physics to me why this happens i.e. why the brakes lock when there is no wheel in place?

[AndreZA]

You can use a flat screwdriver but rather something plastic and just pry the pads apart. No biggy at all. Try and get yourself the spacers for you pads just to transport your bike just to prevent this from happening again.

[JeffD]

Thanks. Why does this happen though when there is no disk in place?

[MintSauce]

The brakes are self-adjusting, meaning that as the pad wears they adjust inwards to compensate for pad wear. They push up against the disc and they will always retract to leave the same distance between the pad surface and the disc, irrespective of wear. Remove the disc and they adjust until they meet each other.

 

You can pry them apart, but be very carful as the pads are generally quite soft and you could damage them beyond use.

 

 

 

[TNT1]

 

 

You can pry them apart' date=' but be very carful as the pads are generally quite soft and you could damage them beyond use.

 

 

 

[/quote']

 

And next time don't depress the brake lever with no disc in the way....

 

[wackwack]

The brakes are self-adjusting' date=' meaning that as the pad wears they adjust inwards to compensate for pad wear. They push up against the disc and they will always retract to leave the same distance between the pad surface and the disc, irrespective of wear. Remove the disc and they adjust until they meet each other.You can pry them apart, but be very carful as the pads are generally quite soft and you could damage them beyond use.

 

[/quote']

 

 

 

I think beyond use is a bit of an over exaggeration - unless you planning to take a 10 Pound Hammer & a chizzel!wackwack2009-08-25 12:16:43

[Musashi]

My easy solution:  take two business card, fold them in two and put them in the place of the disc.

[MintSauce]

 

You can pry them apart' date=' but be very carful as the pads are generally quite soft and you could damage them beyond use.

 

[/quote']I think beyond use is a bit of an over exaggeration

 

 

Not when you've seen someone remove half the pad surface with a large screwdriver while trying to push back the pistons

 

 

 

 

[Guest Big H]

Get yourself one of these.....

 

http://www.chainreactioncycles.com/Images/Models/120/29801.jpg

 

It has an attached spacer (the red thingie on the cable) that goes in the place of the disk rotor and also saves your fork from damage when it is bumped. They are made by BBB and Rav X.

 

Let me try to explain why this happened. In your brake lever is a master cylinder ..... think of a syringe connected to your brake lever. At the other end you have caliper which houses the two pistons with seals. These pistons can move inside the brake caliper. The whole thing is connected by the brake hose and is a sealed unit filled with hydraulic fluid. When you pull the brake lever it presses on the "syringe" or master cyclinder and displaces the brake fluid inside and exerting pressure on the two (or one in some and some even four or six) pistons. These pistons are faced with the brake pads..... or in your case NO BRAKE PADS and the pistons are forced inwards onto the brake rotor or disk. The resulting friction stops the bike. Thers is very little float in these pistons and the pads normally rides very very close to the rotor. The danger is also that you may pop on or both of the pistons out of their housing and may end up with hydraulic oil all over the place. Your pistons moved out further becuase the disc rotor was not in place and got very close to the point of popping out. Better have them checked to see if there were not any seal damage.

 

 

Big H2009-08-25 13:46:40