Advanced geometry help R6

i have a setup that works quite well on a 180 rear tire. I decided to try a 190 rear. The difference in tire size is 16mm, since I only care about axle to ground, it's 8mm. I added 8mm of length to the front end to compensate. It's not the same, it's slow to enter corners, and takes longer to finish them. A local fast guy (a guy I trust and has been at this a long time) has given me some numbers. He wants me to add 5mm more to the front and 5mm more to the rear. However, if it's slow to enter corners, wouldn't I drop the front? I suppose raising the rear accomplishes the same thing. He is much faster than I am also, so I hesitate to use his numbers, based on lap time difference.

 

I would try it, since what you have isn't working. It has been awhile and I don't have my notes, but I think we ran around 292-293 eye to eye on the rear shock without the shim. Right now I can't remember the front, but it was documented in some other threads on here, as a pretty common setup. I do know we had the front end lengthened 10mm and as I recall we seemed to vary from flush on the top to 1 line showing.

EDIT. this was running Dunlops and I think they were 190's. I know they were the GPA's, not current GPA-Pro.

 

I was on the common setup using a 180, and it was working. Trying out a 190 to see if there isn't a bit more grip/speed

His suggestion is 298 rear and 543 front.
I was at 293 rear and 530 front
Currently at 293 rear and 538 front

Forks have been lengthened 10mm and I'm already in the top triple

 

Any know the height of that Dunlop 190 GPA tire Rob is talking about?

 

I think we were at 535 front, measured from center of axle to top of lower triple.

I'm not a suspension expert and there are some on here, so take this with a grain of salt. When my son raced, with a lengthened front end, I don't remember anyone going inside the triple. Your current setup sounds close to where we were.

Is it slow to steer, because you aren't trail braking into the corner? I know some riders brake very hard, and then completely release the brakes before entry, so the suspension comes up, messing with your geometry and then it won't turn. I only know enough to be dangerous on suspension. Often our suspension tuner would have us make 3mm changes. If you lower the front 3mm you will be where we often ran. Changing your front preload, each turn is a mm, can also help when playing with this, however we usually slid the forks in the triples.

 

I believe this was the spec tire in 2012, 13



Click to Order

190/60×17 D211GP-A
Fitment specs Rear: 190/60×17 D211GP-A
Recommended Rim range (5.50-6.00), Best Rim (5.50)
Width (191.3mm/7.54″), Diameter (657.4mm/25.92″)
Available Compounds: 2662 Soft, 7455 Med, 8477 Med+
Suggested Pressures: Hot on the warmers 23psi, or cold 21psi

Note: For street riding, follow the motorcycle owner’s manual for air pressure recommendations. For track or race use, optimal air pressures vary with track conditions but general suggested air pressures are above.

 

I'm Trail braking the shit out of the bike, to the point the front wants to tuck at times.

My initial thought is to lower the front to get the turn in. But there's also a finishing the corner problem, seems to linger a bit longer coming off the apex. Maybe due to a larger tire?

 

I think I understand where the issue is.

I'm going to let this run though just to see what other answers I get.

Thanks Rob!!!!!

 

On finishing the corner, is it running wide? I'm curious what springs you have and what tires are you running? I wish I knew this stuff 100% and I don't, but if you are running wide I would think you have an issue with the rear squatting too much on throttle. So I would guess the fix is, stiffer rear spring, or more compression, or and a mm or two of ride height on the rear, but getting the rear too long can hurt traction, which was something Tyler was always fighting.

It will be interesting to hear what the guys who really know this stuff, like Metric Mike, RM inside, or others say.

 

It runs wider than the 180 did. It's like I'm waiting for it to finish. Front is .95 rear is 550#. I've be told to get a lighter spring, since there's not much preload on it.

I too would like to hear what they come up with

 

Tires are michelin EVO cups.

 

Melka should be here in no time, especially since that is supposed to be the best front tire in the industry. Well, unless it is a rain, we saw what happened with those this weekend in MotoGP.

What does 550 equate to? I'm used to .90-1.05 numbers.

 

550 lbs. I have no idea. I've always know the springs to be in lbs. I usually say the same thing when I see .9, 1.0 when referencing the rear

 

I think RMracing posted some baseline geometry #s a couple years ago.

 

Everyone including myself was using those, what wasn't included in that was tire size

 

how much wider is 190? IMO, if its actually wider, its never going to feel the same. the bike needs more lean angle for every corner. if u try to make the bike get to that lean angle faster, something else will feel different.

lowering the front makes the bars easier to turn, but it doesnt necessarily make the bike gain lean angle faster. i think its more correct to say that in general a bike with a higher CG will be more agile.

543 and 298 is way up there. im much closer to where u started while on Dunlop's 190. id still prob try it anyways just to learn what the change feels like.

 

Front is way too high.

 

Yup. You're riding a chopper.

Go tons trackday and test what works for you.

Do 5 laps then make a change. Keep up till you're happy.

 

He's where my mistake was. The "standard" setup most are using for the R6 was on a 190 tire. I added front end height to compensate for a larger rear, when that was already factored in.

 

Very disappointed in Melka, this thread has been up for 12 hrs with michelin in it. C'mon Greg, get it together.

Michelin Michelin Michelin