16 or 19mm master cylinder?

Andy Preston andy at prestonmedina.com
Sat Jun 18 21:52:23 PDT 2011

Rather than count calipers, count pistons. It's an unfortunate way that 
they are marketed.

The 16x18 is sold as a single caliper master.  

However, the intention is a 4 piston caliper, probably supermotard.

The 19x18 is 
http://www.yoyodyneti.com/ProductInfo.aspx?productid=10.4760.70 sold for 
a 2 caliper setup, but as you noted, thats an 8 piston setup.

So if you just count pistons, a 16x18 would be more suited on stock SV 
brakes. Don't know anyone who's tried it, the caliper piston diameter 
may still not be optimal.

I run a 19x18 on my road bike and 4 piston Brembo's. I used to run a 
pressure switch for my brake lights. However, I rarely braked hard 
enough to have enough line pressure for the lights to come on. After a 
couple of times when I stopped pretty quickly and a car drivers telling 
me my brake lights didn't work I went to this 
http://www.yoyodyneti.com/ProductInfo.aspx?productid=BRP501 . Expensive 
for what it is, but at least reliable.

Those Brembos are trick, I don't regret buying one at all for my road 
bike, I can pretty much stop in no distance from any speed with one 
finger, and add in my pinky when I need to stop even faster. But it's an 
investment, as you need the MC, a reservoir, tubing to connect MC + 
reservoir, bracket for reservoir, and some way of running brake lights, 
either pressure or switch and adaptor. And probably a new banjo for your 
brake lines. I would seriously consider an OEM unit, at least the 
reservoir and brake light switch are taken care off.


On 06/18/11 20:44, matthew patton wrote:
>> Nope, the opposite. A larger m/c will deliver less braking
>> power for the
>> same lever force applied. In this case, braking force will
>> be about 30%
>> less.
> i'm confused. then why are single or double pistons mated to 13mm MC, 4 piston to 16/17mm and 8 pistons with 19/20mm MC?
> Yes, for a given force applied at lever, the smaller MC plunger means more pressure/mm^2, but the bigger the ratio between caliper and MC pistons, the more travel needed at the MC to move the caliper pistons the same amount.
> isn't the reason for the aforementioned pairings to make sure you don't run out of lever before you get enough pressure into the hydrolics?

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