I read on here a while ago that (despite the logical obvious uneducated answer) that the 0.625" cylinder does the front, while the 0.70" does the rear?

Is this the case? If so, please can you explain to me why the smaller cylinder controls the front (bigger) brakes? I need to understand this.

Please and thank you.

 

I'd always assumed it was to do with that fact that the rear brakes should "bite" first for the sake of stability, when the front brakes kick in, as they will provide far more braking pressure. This should keep everything "true" and in shape.

I may be totally wrong, but just always what I'd assumed.

 

Yes it's true but I'm going to let someone else with more time explain why!!

Btw those sizes are a good starting point and not ideal in all cases.

 

pug 205's use .625 and .70, but they also use a .75 on the rear too

 

a smaller bore excerts more pressure per given area, but less fluid movement. and the reverse for bigger cylinders simple !

if your leg excerts 1000psi into the cylinder then proprtionatly the cylinder size will adjust that to the outlet pipe hole. bit like putting your finger over the end of the hose pipe whilsts its running water out.

 

smaller cylinder gives more pressure due to it been smaller, thats why fronts are usually .625, we did find we needed a .75 for rear cylinders as a .70 was to powerful and locked up the back end.

Ratty is setting one up on the gooon and its been a ball ache

 

beaten to it, but basically the larger the surface area of the piston, the less pressure it exerts

 

Theoretics

.625 is a hose pipe
.70 is a drain pipe
.75 is a sewer pipe

Put the same fluid into them and the hose pipe will give you greater pressure (less volume)

The sewer pipe will give you less pressure (higher volume)

Simple

 

so its like the difference between a nice tight fanny, and throwing a wand in the albert hall?

 

So, you're saying that a Sewer Pipe is only .125" bigger than a Hose Pipe?

You sure about that?

 

Remind me not to bother with the in depth technical descriptions next time

 

You do, of course, know that I was joking. right?

 

so this info means that i have my bias box cylinders the wrong way round no wonder they are as hard as nails & the bite is shit ill swap them round then .

 

I'd be interested to know what the effect would be of having them the wrong way round.