Stock 2023 V4R front master cylinder

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I’d love to hear what a stock V4R brake setup is like! It sounds atrocious and surprising it’s so different from my V4S’s setup.

From your lack of answering the question, I’ll take that as you don’t know. You’re literally changing a component that you don’t even know if you really need to change.
 
Original R is 16/21. For comparison area is 64 times PI (I'll ignore PI). 19RCS area 90.25 so 90.25/64= 1.41 RCS is 18 pivot vs 21 which lowers force. 1.41 times 18/21= 1.208. The lever requires 20 percent more force, way wooden. The 17RCS is about 7.5 percent higher with the 20 pivot and the PRS 18/19 (belt drive superbikes) is about 15 percent. There's a reason why the RCS 17 or Corta Corsa 17 is preferred with the stock calipers.
 
baggerman said:
Original R is 16/21. For comparison area is 64 times PI (I'll ignore PI). 19RCS area 90.25 so 90.25/64= 1.41 RCS is 18 pivot vs 21 which lowers force. 1.41 times 18/21= 1.208. The lever requires 20 percent more force, way wooden. The 17RCS is about 7.5 percent higher with the 20 pivot and the PRS 18/19 (belt drive superbikes) is about 15 percent. There's a reason why the RCS 17 or Corta Corsa 17 is preferred with the stock calipers.
Click to expand...

I’ve been running the SP2 at 16/20, which is pretty close to what the V4R has, so I have some idea how it will feel. It felt quite soft and a lot of lever travel was required. I needed to wind the lever out quite far so that I had room to pull the lever (and I don’t think I hit the brakes particularly hard). Same calipers except for the vented pistons on the SP2, which are irrelevant to this discussion.

Brembo recommend 17 BUT Ducati ignore that and provide 16 (maybe they feel it’s safer and even more so on the street). A LOT of people and both suppliers I am speaking with strongly recommend the 19. One guy uses the GP 19x18 (which wouldn’t be any different for me than the billet 19x18) and reported that it had a load more feel than the RCS he previously used, gave him a lot more confidence and doesn’t feel wooden at all. A couple of other people have reported the same using 19.

I get what you are saying about the mathematics but I do find it interesting that I am getting some consistent recommendations for 19 from the suppliers (who have both in stock) and some decent riders that I know. Have you tried these with Stylema or GP4-MS calipers to come to the conclusion that the 19 does feel wooden or are you basing that conclusion on mathematics?
 
So the belt drive master 18/19 gives you 15% if the 7.5% feels too mushy. That master uses the same casting as the V4's and is titanium like the V4's. Direct bolt on. I have one of these lying about. I'd like the lever firmer but not 15% so I'll bush the lever pivot hole and move the pivot to 18. Which gives me about 8.5%. I haven't tried a 19 RCS.
 
baggerman said:
So the belt drive master 18/19 gives you 15% if the 7.5% feels too mushy. That master uses the same casting as the V4's and is titanium like the V4's. Direct bolt on. I have one of these lying about. I'd like the lever firmer but not 15% so I'll bush the lever pivot hole and move the pivot to 18. Which gives me about 8.5%. I haven't tried a 19 RCS.
Click to expand...
‘Belt drive master’?
baggerman said:
BTW the 16/20 is softer than the stock one by about 5%.
Click to expand...
Not a huge margin and similar enough that I’m doing the right thing by changing it.
 
Bevels, belts, chains the evolution of Ducati camdrives. That master's off the 1098s/1198s. My point about it being softer is the change in percent is the change in lever travel. That one you had used up 5% more lever than the stock one. I'll put the 18/19 on my bike (15% less lever travel) and I'll post what it feels like. Maybe OK as is. Too cold to ride here.
 
Good maths by bagger. Modern bikes are notorious for softer braking systems due to the ABS block and longer lines. That’s why I don’t get why you don’t just bypass the ABS block and run lines direct to the calipers. Save yourself lots of time and money and you’d be working the problem up properly instead of just throwing things at the wall and seeing what sticks.

One other thing to consider is that the 19 might help mitigate the softness of the 16 when running through the ABS block so there’s that.
 
I’ve done both on track 17 is a better feel and working ratio to the std callipers.

You can’t change the size of the callipers because that’s what the ABS needs to see to work correctly.

You can’t remove the ABS because the bike needs its info to work correctly

Conclusion 17 on a 18 or 20 ratio is correct and an improvement in feel and operation
Amen!
 
!7 RCS is softer/longer travel than the stock master with the pivot on 18 about 2.5%. 7.5% firmer with the 20 pivot. 19 RCS was used with M50 calipers primarily. I'm still going to try the PR 18/19 but expect it to be too wooden. Looks pretty easy to make a couple of plugs for the lever pivot holes to be able to move the pivot 0.04 or .06 inch (1 mm or 1.5 mm) which would give you very similar lever response to the 17RCS with a 20 pivot.
 
andyb said:
I’ve done both on track 17 is a better feel and working ratio to the std callipers.

You can’t change the size of the callipers because that’s what the ABS needs to see to work correctly.

You can’t remove the ABS because the bike needs its info to work correctly

Conclusion 17 on a 18 or 20 ratio is correct and an improvement in feel and operation
Amen!
Click to expand...

Was that using non-R Stylema calipers (or 4x30mm calipers)?

I wasn’t thinking of changing caliper size.

Also no intention whatsoever of removing or bypassing ABS.

17 is certainly the recommended ratio by Brembo (ignored by Ducati and KTM of course) and seems popular.

I would have already ordered the 17RCS CC but the number of strong recommendations for 19 have confused the issue for me. I sort of fancy the billet as well and quite a few people have told me they switched to this from 17RCS and much preferred the feel (which is subjective of course) but that they don’t think it feels wooden at all.

I used to be indecisive but now I’m not so sure.
 
baggerman said:
!7 RCS is softer/longer travel than the stock master with the pivot on 18 about 2.5%. 7.5% firmer with the 20 pivot. 19 RCS was used with M50 calipers primarily. I'm still going to try the PR 18/19 but expect it to be too wooden. Looks pretty easy to make a couple of plugs for the lever pivot holes to be able to move the pivot 0.04 or .06 inch (1 mm or 1.5 mm) which would give you very similar lever response to the 17RCS with a 20 pivot.
Click to expand...

That’s interesting. So 17RCS set to 18 would be a softer feel with longer travel than the OEM 16x21 and set to 20 would not be that much firmer or shorter travel.

Wouldn’t that mean the 19x18 might not actually be too firm? There’s a 19x16 as well. The Galespeed calculator recommends a total ration of 85-95 for track use - 19x18 is a bit lower than that and 19x16 is within it.

Thanks for the responses - it’s an interesting subject.
 
can't wait to see it when you discover you can move your bars forward and back and get ones that rotate so you can alter the angle of them, let along getting wider bars and the trappings that come with that.
 
I have a rcs corsa corta 19 on my sp2 I decide to change it because the soft feeling of the oem was confusing me. Now with 19 I have a direct feeling and braking as I prefer.
 

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