Setting up geometry

Ive been chasing for so many years suspension issues with ever getting the bike to handle like a knife carving through butter.

I know nothing of suspension, so I always ask for help from suspension tuners. Clickie here, clickie their and still not perfect.

Kept saying feels like the bike is not properly align (geometry maybe?) but alll they keep doing is clickie clicks.

So this past Ocotber, I decided to raise the rear and the bike felt so much more planted, but since I raised the rear plus added a taler rear tire (200) I couldn't get the rear to hook up.

I do think I finaly hit the nail on the head and know my issues were all due to geometry.

So by question is, HOW DO I CORRECT/SET GEOMETRY ?

trail and error ???

Thnx

 

Did any of these "suspension tuners" suggest that changing geometry might be the answer? If all they did was "clickie-clickie", I think you've given them a title they don't really deserve. "Screwdriver operator" might be better.

Geometry must be in the ballpark long before the clicking starts. My suggestion would be to find a suspension guy who is willing to make geometry changes at the track and work with you during trackdays or race weekends. He will undoubtedly cost more than the screwdriver guy. One weekend of that (with an experienced tuner) will probably have a big effect that you can then fine tune with smaller adjustments.

Having some kind if data acquisition is tremendously helpful. Doesn't need to be Marelli or pro level, but travel potentiometers are not terribly expensive to add to something like an AIM system.

You can continue guessing, and you might hit the nail on the head again, but it will take much, much longer.

 

The only way to truly understand is to do some trial and error. Yes there are 'ball park' numbers because sportbikes haven't really changed geometrically in 20 or more years. Here's a couple of basics from 30,000ft that you can keep in the back pocket; just basics, not by any means a conclusive list. Also worthwhile to keep in mind every change you make to geometry has multiple effects - there is no free lunch.

The big numbers that matter and how they affect the bike.

Wheelbase - Generally 1500mm +/- : Longer wheelbase requires more lean angle to traverse a given arc, but generally increases stability.

Rake(angle) and Trail (distance) - generally between 23-25 degrees from the vertical and 90-105mm. Steeper the rake (lower the number) and lower the trail amount, the quicker the bike will be to respond to handlebar input at the expense of stability and will less self righting when leant over.

Swingarm angle - Generally 10-13* from the horizontal. More swingarm angle increases antisquat.

Center of Mass - As you raise the center of mass of the bike it capsize faster and have more ground clearance for more lean angle. Lower will provide a smaller leverage arm for wheelies and stoppies to occur and will make the bike less susceptible to input.


To touch on your initial post - when you raise the rear of the bike you steepen the rake slightly, reduce the trail slightly and also increase the front weight bias slightly. Two of these things would make the bike faster/twitchier to steer, and the other would provide a little more feedback from the front tire. Additionally, you've also increased the swingarm angle and antisquat which would provide more drive grip when exiting a corner, especially when lean angle is still present.

 

There are many diff levels for the skillset of suspension tuners. Generally, the bottom are the guys that turn knobs and set sag for street and trackday riders. Somewhere in the middle is your avg tuner at club races. And at the top are the guys that are employed by pro race teams or suspension manufacturers. IMO, at a minimum you want to be working with someone that has previous experience with Expert race winners on your bike with your tires. Those tuners should have run through a huge range of settings and geometries with riders that know how to push and give feedback. Theyll have a good baseline and will know which direction to go should you have any issues, because theyve done it all before. Pay those tuners for their setup numbers and go from there.

You can do the tuning yourself. The process should go like this:
1. Identify problem
2. Make change
3. Better, worse, or no change?
4. Any positive or negative side-effects?
5. Repeat until you run out of time

This process will take a beginner tuner years to learn how to find a good setup, especially if they are teaching themselves. You probably dont yet know what each of the ~40 possible setup changes can do, nor what the results feel like. It'll take forever to explore most of them repeatedly. You may not yet know what exact issues are preventing you from going faster. You may not know what a bike should feel like for your riding, plus your riding will change over the years. It's A LOT to learn and pay attention to. Plus your biases and your mind will play tricks on you the whole time.

The thing you must learn to work with any tuner, including yourself, is how to give proper feedback. Things go a lot better if you can clearly describe issues that you are feeling, in terms that are understood. "Planted" and "hook up" are not that clear. Where on track was the bike better - entry, midcorner, exit? What was better - more grip, faster steering, easier change of direction? Was it better on, off the brakes, or both? Did the rear start to spin or slide? Where? What were you doing with the throttle then? Etc etc. Think about these answers and take them to a pro.

 

You ever think to call/visit John Sharrard at Accelerated Technologies in Ontario?

 

I've worked with him in the past but he's no longer at the track like back in the day.

I've also worked Jon Corwell "Corndog" (Jake Gagner's crew chief suspension dude) but didn't get the results I wanted.

Thing is often, when you're not a Gagne, they might not always give more time then they can.

They both have helped me a lot in the past but unfortunatly, they are no longer at trackside, reason why I'm asking and will take matters into my own hands I guess.

Don't want to make a fool of myself at the next D200 !



Thank you all for your help and I will put all the info writen here into practice for Jennings, the Tuesday before the D200.

 

If you're trying to get to a base line why not call Thermosman now and get some ideas of what to change before the big D and hire him to help you at the 200?
And will the rears you use at Jennings be different width/diameter from Daytona tires?

 

Alex you need to talk to Thermosman. You're on a ZX6 and he helped Stefano with that bike for years. Have you measured any other fast guy's ZX6?

Are you able to communicate exactly what you want the bike to do differently that it's not doing now? This is (one of) my problems, I know right away if it's better or not, but sometimes I don't really know what I want to be better. That's why riding different bikes has helped me a lot over the years.

 

Some ideas for the trial and error route:

Supersport so you're using stock triples, right?

The new Dunlops added +4mm of ride height- so if you're using the new rear and an old front that is a huge change. Assuming you're using the new front AND rear-

If you raised the rear (how much?) and the bike front felt more planted (turns in better, holds the line, doesn't run wide on acceleration) then I would lower the rear a bit- maybe halfway as much as you raised it, and lower the front a bit.

Another thing to try is less preload on the rear shock, or softer rear spring with your current geometry. Does the rear pump under acceleration? Raising the rear probably affected the swingarm angle and it's topping out when you get on the gas due to chain pull/ too much preload or too much spring for that particular rear ride height.

Since I was in Montreal last week, I'm pretty sure you're not riding any time soon, so you have all winter to think about it?

 

Setting as bike up for Daytona is so different than setup for any other track...it's all about maximizing rear mechanical grip because the tires are rocks and the track is slippery. Don't over analyze the setup, concentrate on getting drive out of 6 and the chicane without losing initial front end turn in grip. The rest is pretty simple - get it plush over the bumps, stay on two wheels, and try to relax.

 

What should he do if he's running the other tire brand that's won a bunch of recent 200s?
Or the other ones?

 

Trying to figure out if you're taking the piss.

 

Huh? The last I saw and read in Alex's bio was he was running BStones so hence my question?

 

Yes, Bridgestone will have on hand the tires for the D200 at Jennings.

 

Big issue is the front at Daytona, since I moved to Bridgestone.
I need to feel better on the front or else I loose WAY TOO much time in the corners when trying to exit them. Especially the slow corners like both Horse Shoes.

 

I'll ask Mike from KWS to set the bike like Stefano's bike (we have the same - if he still has his ZX6R)

I thnk that base line will be better to start off with.

 

I’ll throw another vote in for Thermosman. He tweaked the geometry on my ZX6 at Barber and I immediately felt better and went faster.

Do you have a shim kit for the rear?

 

You weren't. Never mind.

 

Hence the need for concentrating on your exits, however remember that your lap times will benefit more from better exits at 6 and the chicane.

 

Don't think I do have a shim kit for my rear.