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Discussion Starter #1
I had been having issues with not having enough weight on the front and not getting good turn in and the tire wouldn't warm up. The easiest thing to do was to lengthen the shock at the bottom clevis and I raised it about 2mm from stock length and adjusted rebound/ compression on the front and it solved my issues. I heard a couple of people at the track suggesting to adjust the forks first. So what is the difference between raising the rear and dropping the front? Wouldn't there be a similar effect with swingarm angle and rake?

What's a good baseline for 13+(includes 19+ :D) models?
 

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I had been having issues with not having enough weight on the front and not getting good turn in and the tire wouldn't warm up. The easiest thing to do was to lengthen the shock at the bottom clevis and I raised it about 2mm from stock length and adjusted rebound/ compression on the front and it solved my issues. I heard a couple of people at the track suggesting to adjust the forks first. So what is the difference between raising the rear and dropping the front? Wouldn't there be a similar effect with swingarm angle and rake?

What's a good baseline for 13+(includes 19+ :D) models?
Mathematically there is a difference but I couldn't tell you what without doing a bunch of measurements and calculations. 2 mm change on the shock length has a different effect to rake/trail/swing arm angle than 2 mm change on the forks. It varies by bike too all based on how the shock is mounted, the linkages used (if any), etc. Tough question to answer exactly.

The other thing it affects is overall ride height. Do you want to have a higher rear end or a lower front? In theory it's possible to achieve the same rake/trail/swing arm angle setup by only adjusting rear height as you would by only adjusting the front height, but then the difference is in the height. With one setup you'll have a higher overall height than with the other which affects your center of gravity.
 
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Man, seems like you and I mess with the suspension a lot.

From what I was told the biggest difference between raising the back and lowering the front to get overall better turn in is ground clearance. The stability difference between raising the rear versus dropping the front is minimal. I have heard that you should focus on raising the rear before lowering the front for what it is worth. I have raised the rear 3/16" which put my seat 11mm higher. Planning on going another 3/16" and see how it works out at the next track day. Then maybe drop the forks a couple mm's and so on until the bike becomes unstable. Then back out 1 move. But I want to raise the rear twice before I lower the forks to keep my seat height up and keep ground clearance as high as possible.

I had a buddy on an R6 show me some measurements he took when messing with his geometry. Making the same move in the rear and the front (raising the rear, lowering the front). He was able to get ~0.5 degrees more lean by raising the back, and ~0.5 degrees less lean by lowering the front.

Hope this helps.
 

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Do you know what your swingarm angle is?
rake?
trail?

Those are pretty important numbers to know to really start making changes......

3 different bikes, 3 different results- 3 different riders liking somehting different.....but generally 10-12* swingarm angle is the sweet spot
 

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So what is the difference between raising the rear and dropping the front? Wouldn't there be a similar effect with swingarm angle and rake?
The biggest difference is that raising the rear also affects where you sit in the linkage curve for rear suspension response and the chain pull angle, which affects rear squat under acceleration. For fast riders swingarm angle is a big thing to get right because it can have a major effect on handling when coming off corners.


Mark
 

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Discussion Starter #9 (Edited)
Do you know what your swingarm angle is?
rake?
trail?

Those are pretty important numbers to know to really start making changes......

3 different bikes, 3 different results- 3 different riders liking somehting different.....but generally 10-12* swingarm angle is the sweet spot
Thanks. Just ordered a digital inclinometer.
 

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10* is very flat... running wide and having on the throttle steering issues will be forth coming. 12-13 is more in the range that works, especially for low powered 600's (including 636's over 125hp). I like about 12-12.5 so the rear just barely gets squirming when I squeeze on the gas at the apex.

Even on 200hp literbikes, they set the anti squat in this range. Once you past 13.5ish degree's rear edge grip starts to go away and you really need to have sensative throttle control to make it work. It's great fun on point and shoot tracks, but I've been thrown out of the seat using 5% throttle at over 55* lean with a 13*+ swingarm angle.
 

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Is it legal in racing to change the shock linkage?
In Superstock classes, it's mostly not allowed. Check the organization rules to be sure. In Superbike classes, it's usually not an issue, bottom line, check with the organizations rules to be sure.
 

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10* is very flat... running wide and having on the throttle steering issues will be forth coming. 12-13 is more in the range that works, especially for low powered 600's (including 636's over 125hp). I like about 12-12.5 so the rear just barely gets squirming when I squeeze on the gas at the apex.

Even on 200hp literbikes, they set the anti squat in this range. Once you past 13.5ish degree's rear edge grip starts to go away and you really need to have sensative throttle control to make it work. It's great fun on point and shoot tracks, but I've been thrown out of the seat using 5% throttle at over 55* lean with a 13*+ swingarm angle.

When measuring the swingarm angle: are we talking with the bike on it’s own weight alone, or with the rider onboard? I would think that would make a difference.
 

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This is the tricky part. You can't have the bike on stands OR on it's own weight to get an accurate measurement. The tires must be a hair off the ground to see the static angle.

Personally, I don't bother with this every time I change the angle. The first time, yes. However, after the initial setup I just make 1mm adjustments and see how it feels. Chasing numbers isn't going to make you faster unless you're at the sharp end of the white plate's.
 

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This is the tricky part. You can't have the bike on stands OR on it's own weight to get an accurate measurement. The tires must be a hair off the ground to see the static angle.

Personally, I don't bother with this every time I change the angle. The first time, yes. However, after the initial setup I just make 1mm adjustments and see how it feels. Chasing numbers isn't going to make you faster unless you're at the sharp end of the white plate's.
It just seems like a dynamic number: bike off the ground/bike on the ground/rider on the bike/under acceleration/under deceleration - the number is constantly changing. Tough to chase a constantly changing number.
 

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Discussion Starter #16
Is it legal in racing to change the shock linkage?
Too bad there aren't any aftermarket linkages available for our bikes. The 13+is a little more progressive than previous years.
 

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Neonmarine;1839774I like about 12-12.5 so the rear just barely gets squirming when I squeeze on the gas at the apex.[/QUOTE said:
So you are trading edge grip for turning response with that? I'm not fast enough to really notice as long as it isn't way outside the range of OK but it is interesting that you can play with the feel like that.


It just seems like a dynamic number: bike off the ground/bike on the ground/rider on the bike/under acceleration/under deceleration - the number is constantly changing. Tough to chase a constantly changing number.
It is a dynamic number, but measuring at full droop allows to you always have a consistent baseline to see how much you have changed the angle to start with. The interactions between the static angle and shock settings/performance make it hard to sort the various settings and effects from one another. In the end it is rider preference and feel that matters.


Too bad there aren't any aftermarket linkages available for our bikes. The 13+is a little more progressive than previous years.
There might be a business opportunity there, but I doubt it. If links are not supersport legal then there wouldn't be much of a market for them.


Mark
 

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When measuring the swingarm angle: are we talking with the bike on it’s own weight alone, or with the rider onboard? I would think that would make a difference.
It just seems like a dynamic number: bike off the ground/bike on the ground/rider on the bike/under acceleration/under deceleration - the number is constantly changing. Tough to chase a constantly changing number.
Starting point for my comment of 10-12 being the useable range "sweet spot" is bike sitting on its own weight perfectly upright

but yes the angle chages with a rider on board, going on gas or off, over bumps and dips, on the brakes or off etc........... but my starting point has always been as I described above
 
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So you are trading edge grip for turning response with that? I'm not fast enough to really notice as long as it isn't way outside the range of OK but it is interesting that you can play with the feel like that.

Mark
Well it's hard to really explain on the internet, but basically I'm trying to use the throttle in the exact same way I would with less swingarm angle. The difference is how much the bike rotates when you open the gas. If the angle is too sharp, then you can have an off throttle highside (done that, not fun). Not enough, the bike will squat under load and plow the front on exit. So its a fine balance when you start raising the rear. Start with the stock geometry and make small (1mm) adjustments and see what feels good.

Also, keep in mind if you don't want to jack up the front end feeling of the bike, you need to raise it correspondingly. Otherwise you start messing with trail numbers when you really only want to change swingarm angle. Oh and you need to add preload when you raise ride height. How much is debatable, but a rule of thumb is for every 1mm of added height, give the preload 1 full turn. The reason for this is that you are changing the weight balance and the center of gravity will have more leverage on the tire as it goes up. Adding preload helps retain the "feeling" from the previously lower setting.
 

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So I've been reading these posts off and on and feel the inclination to throw in my unsolicited two cents. There is a plethora of data on our bikes, especially the older ones. I'm not saying anyone shouldn't fuck with their bikes, but I'm saying I think you can avoid a lot of "trying to reinvent the wheel" and just get your suspension serviced/setup by someone that's been in the business for years and knows what they're talking about. Personally, I use Thermosman, but there's a ton of great guys out there. Get your baseline, and now you have something to go off of, and if you get too far off track, you always revert back to your baseline.

I would also caution against trying to make any major drastic changes until you reach a consistent A group pace. Speed certainly isn't everything, for sure. But I can say with certainty that I've worked with hundreds of Novice/Intermediate track day riders that have about 10 million other things to work on that's more important than their bike setup, and that's themselves. Work on the loose nut holding the two bars. I have seen 'veteran' Intermediate group guys bitch and moan about the bike not wanting to turn, all while never trail braking. Our bikes are inherently designed, and engineered, to turn in on the brakes. So while you can totally backwards engineer the bike to turn easier without using the brakes, you're not doing yourself any favors until you develop the skill, and in fact, might be hurting you later on as your skills progress because now the bike will be far more unstable during braking/corner entry.

I remember being at Barber and this guy in Intermediate was chasing tire pressure all day, convinced that 1 or 2 PSI difference was causing all these issues for him. He was turning 52's. There could have been a lot of issues with his bike, I wouldn't know as I never rode his bike. But what I do know, is that you can't get reliable feedback from a bike only running 52's at Barber.

A solid baseline setup from a good suspension person will serve you well into the pointy end of A group/mid pack Expert. I never changed springs in my R6 (when I had it) from what Thermosman gave me. Managed to podium a few times with it. In fact, Tman never worked on my bike in person. I always mailed my suspension to him. Never set sag, never checked the swingarm angle, none of that. He helped setup the endurance bike to where it's at now, and I think has touched the bike twice ever. We haven't changed the rear spring, rear height, or touched the rear outside of a few clicks of comp/reb and preload. Changed the fork springs one time, adjusted the oil height slightly, but that's been about it in the 3 years we've been running it. We've won a few races on it at this point, so the bike is most certainly capable as it sits.

TL;DR - Ride more, fiddle with knobs/geometery less.
 
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