Ok so my question is, by putting a 19x18 lever on a 19x20 master am I changing the ratio? Am I wrong?
FWIW, I stick with whatever lever originally came with the m/c or whatever lever(s) the m/c's mfg offers as alternative levers for that m/c. Unless someone knows for certain that the combo you're attempting works (you're gonna have to mention brand names), I wouldn't go into it with any expectations of success. If, by chance, that 18 lever is provided as an alternative to the 20 lever and all by the same mfg then the answer to your question(s) is(are)... Yes. No.
I think you're in luck but I can't say for certain. To reiterate, yes, you will be changing the ratio. Going from 20 to 18, you will also have to pull the lever farther for the same amount of brake pressure but it wont be harder to do. In fact, it will be easier. Your "control" of that brake pressure will be enhanced but your "feel" will be diminished. The good, you can more easily increase pressure. The bad, you can more easily add too much pressure While getting used to the new ratio, just don't go grabbin' a handful. You could try the RCS lever. I see no reason it wouldn't fit any less than I see any reason an 18 lever can't replace a 20 lever, or whatever I'm tryin' to say there. Why would anyone want the RCS adjustability? Some tracks demand braking finesse, some tracks don't care how hard you hammer the brakes, some tracks require a lot of braking, some tracks require very little braking...and, how hard can you work your brake fingers before your braking becomes inconsistent due to fatigue or your modulation of that lever becomes inaccurate, also due to fatigue?
I've always used the 19x18 but scored a stupid deal on a billet 19x20. My plan was to just swap the lever or replace it with a 19x18. If it doesn't work this way I'll sell it and buy a proper 19x18 but the deal was too good to pass up.
Geez, you coulda tried the swap before askin' about it. Do you have any idea how much (wasted) time I spent thinkin' about this so as not give you a wrong answer. My whole day is shot, my brain is fried, my internal balancing gyroscope has warped and the pads that dampin' its oscillations of mental instability due to over-heating have glazed. My vice-like mind has lost its grip and, now, I have to order a whole new Brainbo system just to keep from over-revving as I attempt to catch up with myself... <sigh> BTW, I think the only difference between one Brembo m/c and another like/similar Brembo m/c is the lever and its ratio. I could be wrong. There could be a lever issue when going from one type of Brembo m/c to another type of Brembo m/c... I could be wrong about that, too. In fact, I'm sure a lever for a base model Brembo m/c supplied by OEM mfgs won't fit their top of the line m/c. But I've been wrong before... At any rate, I hope it works for ya. Whatcha gonna do with the old m/c? I have a need.
Well now I think we've come full circle and still don't really know! Lol. My thinking is it just changes the lever pivot but I've never tried this before, I always just bought the 19x18 and used the lever it came with. If this doesn't work I'll have a sweet deal on a billet master
I'm thinkin' the different levers only change the distance from the pivot to the piston. In every pic I've ever seen, the only difference I could discern was that different distance. It's the same pushrod (I checked the numbers) and appears to be the same m/c housing (which I didn't think to verify).
I looked again. I don't have access to the housing part numbers, and the RCS lever uses a different pivot pin which could mean a completely different housing or just machined differently...or they just wanted a fancy pin to go with that fancy lever.
moving the master relative to your hand also changes the lever ratio. move the master left, the lever ratio increases. move the master right, the ratio decreases. given how little the master can move on some bikes, its not a huge change. but its something u can play with to find the best feeling for u.
Well I guess some testing is going to be necessary. I already use the very end of the lever with one/two fingers. If I tried three I'd be using the ball end.
Now why did you have to burst my bubble! I was wondering because you're moving the pivot point. You'd think they'd just stamp "19" on the top and then you choose your lever... Maybe I'll just sell it.
Regarding the actual master cylinder dimensions, no they don't change if you swap levers. It's the actual dimension of the piston inside. The discussion about changing ratios from different levers is silly. If you grab it closer to the master VS towards the edge of the lever that will change the pull ratio just the same.
nope. the lever ratio changes if u adjust the distance from the pivot to the pushrod on the lever. see the Brembo RCS and its adjustable lever for an ez example. the geometry isnt as nice if you are "bending" the pushrod, but its still a diff lever ratio.
