Handlebar Master cylinder query

[Major Softie]

It's looks to me that the brake pivot point on BMW handlebar MCs is the same, and the position of your hand is also the same as it is determined by the twist grip position, so a longer lever would not have much effect. Is it not the ratio between the master and slave cylinders that is important?

Everything else being equal, yes. Jean was speculating that everything else may not have been equal.

[Jean]

True. The ratio between the MC and the slave is what's important, but the effort YOU have to put into the MC operation is something to consider.
When you get in this situation, everything else is rarely the same.
Of course, this comes from ASSUMING that nothing else had changed when troubleshooting other problems, and THEN finding out that it ain't necessarily so.
So, to repeat...changing from a 13mm MC to a 16mm MC presents an ugly challenge to your (Mine, anyhow) right hand unless you like to do stand-on-the-front-wheel stops.

[Darryl Flynn]

Thanks Guys . I now have a 14mm and 16mm master cylinder in my possession and assuming that the 14mm will present the better result will use that and sell the 16mm. As i have managed to pick the 14mm up for £16 i am not continuing to search for a 13mm and instead will concentrate on strengthening my grip somehow

[Jean]

Eat spinach.
I think you have made the right decision.

[SteveD]

Eat spinach.
I think you have made the right decision.

Jean is missed!

How would a right throttle assembly with a 12mm master cylinder from a R80ST go on a R100 twin brembo setup, replacing the stock 15mm.
Clearly lever travel will be further, but might it be too far?

[bbelk]

How would a right throttle assembly with a 12mm master cylinder from a R80ST go on a R100 twin brembo setup, replacing the stock 15mm.
Clearly lever travel will be further, but might it be too far?[/color]

Interesting - three years and two days between this post and the last.

I think a 12mm master would be too small for duel disks. Your leverage would be great so you wouldn't need the spinach, but you may run out of travel on the lever.

[Major Softie]

How would a right throttle assembly with a 12mm master cylinder from a R80ST go on a R100 twin brembo setup, replacing the stock 15mm.
Clearly lever travel will be further, but might it be too far?[/color]

Interesting - three years and two days between this post and the last.

I think a 12mm master would be too small for duel disks. Your leverage would be great so you wouldn't need the spinach, but you may run out of travel on the lever.

That would be my guess as well. I can't swear to it, but I'm pretty sure.

[George Ryals]

It would be a simple arithmetic project to figure out how far a 12mm piston has to travel to make an ATE caliper piston travel the required amount to apply the brake. Then its a matter of measuring the lever mechanism to find out how far the lever moves to move the mc piston the required amount.

Does anyone know how far a 38 and/or 40mm ATE caliper piston moves to apply the brakes. I'm guessing its less than .5mm.

[SteveD]

Thanks lads. I suspect the 12mm m/c would allow too much lever travel. The offer for the 12mm was cheap though, so worth the question.

[Major Softie]

Thanks lads. I suspect the 12mm m/c would allow too much lever travel. The offer for the 12mm was cheap though, so worth the question.

You may want it someday for a single disc application. If it's that cheap, you may want to jump on it anyway.