Brake pipe bore

Is there any reason why the bore of a brake pipe has to
be the size it is? If the pipe is only use to transmit preasure
from one end to the other could the bore be smaller than it is?

Cheers taz.

 

Smaller bore probably means higher friction losses in the pipe (it would
have to move faster and further). Also, the fluid may therefore be
unable to reverse flow fast enough when the brake lever is released.
Don't know what the ideal flow rate is but suspect that it is better to
be slower rather than quicker (bigger rather than smaller bore) to avoid
friction losses and other issues associated with hydraulics.

 

Dunno if this is of any help, but the aftermarket braided hos
--
Dan L (Oldbloke)
My bike 1996 Kawasaki ZR1100 Zephyr
M'boy's bike 2003 Honda NSR125R
Spare Bike 1990 Suzuki TS50X
BOTAFOT #140, DIAABTCOD #26, BOMB#18 (slow)

es always seem to be a smaller bore than the original rubber hoses. mined
ewe, this is purely as viewed fro the exterior, rather than looking at the
hole size, iyswim.

 

Well, the pad does move a bit. Which means the piston moves a bit.
Which means the fluid moves down the hoses.

ISTR that there's a version of braided hose called microbore, or
similar, which is meant to provide some improvement, but I can't be
bothered to do the physics now.

 

I just had a conversation with a mechanical engineer with some amount of
hydraulic knowledge. He reckons that there will be a small improvement in
brake feel due to lower stress on the smaller ID brake hose. Same sort
of improvement that you get from going from a somewhat 'springy' rubber
brake hose to a braided stainless covered hose, although probably not
the same magnitude of improvement.

He wasn't able to say where the crossing over point would be, between
improved feel and and unwanted restriction in fluid flow from the
reduced diameter.

My take on it is that I wouldn't go for anything drastic, changing from
3mm ID to 2mm ID should be safe enough, but as far as there being a huge
improvement, I'd doubt it. I'd certainly not pay a premium for it.

 

I just had a conversation with a mechanical engineer with some amount of

I'm not quite sure of the internal size of the pipe on it, at the moment
but if the external size is owt to go on then it would be about 6mm.
They are not braded steel ones though. I was going to use a stainless
steel braided hose that in comparison seems much less in diameter.
If 3mm on a braided hose is OK Then the ones I have will do just fine.

Cheers taz.