Let me start by first promising, I completely HATE having to learn the same lesson twice. Yet here I am, it’s nine years later and I’ve done it again. It’s ok though, if I can’t learn from my own mistakes, maybe you can.
It’s 2002, I race back east, and we dominate on our Ducati 998. You’d think a man would be satisfied with that.. But no, I’ve got to go faster. Thing is I couldn’t figure out how. Back then there was a big push going on from a company called GMD Computrack. They’re still around now, and they’re great. Wonderful way to know what’s straight, and where your chassis is at. But just like anything else in life, too much of any one thing is no good. I see on their site that they still boast a fantasy place they just love calling the “Sweet Numbers”. Best thing I can tell you right now is, there is no such thing. There is no one set of “Sweet Numbers” for every bike. How do I know this? Pinky finger, right hand, 2002 - one hour after paying them to apply their “Sweet Numbers” to my 998. Worst setup motorcycle I have ever ridden, never mind raced. Smashed bike. Angry people. Blood all over the place. “Never again…”
If you are a roadracer, well there’s a pretty good chance you’re in idiot just like me. And you’re likely desperate. And you’re probably confused more often than you’ve got a clue. If you’re a roadracer, you need to be very careful of one extremely alluring thing – the answer.
The last two years of my roadracing career are by far my favorite. Not because we won, we didn’t. They are my favorite because we took our Superduke which did not work on a racetrack the way we needed, and made it work really well. It took us a while but once we figured out the right direction to go, we continuously changed that bike, and we continuously went faster on it. One of the most vital things we learned about developing our Superduke, was the affects of altering it’s rake and trail.
If you study that image you will understand that the “rake” of your steering head pretty well got fixed there when they welded your frame together. But that doesn’t mean you can’t alter it. Push your forks down into your top triple clamp, bam, you just altered your rake by lifting the front of the motorcycle up. Study that image a bit more and it’s easy to see where your trail comes from – draw a simple vertical line straight through your front axle and down to the ground. The distance between where these two lines hit the ground is your “trail”.
Here is where it gets interesting. We found last year that our Superduke was fastest around a racetrack when we pushed the forks so far down into the top triple clamp, that we had to make a custom triple clamp. Originally our Superduke had about 92mm of trail. That is VERY steep. By the time we were through with it, as pictured in the image below, it had @ 100. That is more common. And it was beautiful.
So far that's all great, but HERE is where I blew it this past winter. When we looked into racing the RC8R, immediately I researched it’s rake and trail numbers. Holy hell, I thought, it had numbers similar to what the Superduke had when it rolled off the showroom floor. And as we learned from racing our Superduke in stock trim in 2009, this particular geometry put us on the ground far too often.
So the first thing we did was bring an RC8R to a local chassis guy here in the Bay Area. He measured our bike, punched a few numbers into his computer, and gave us his best recommendation to set up the RC8R to race - "Change the offset from 28mm, to 24mm. That will give you @ 105mm of trail - then you can slide your forks up or down in the clamps to fine-adjust from there.." Holy hell here we go again, I thought. So we set out searching for adjustable triple clamps for the KTM RC8R. Problem was, no one sells off-set triple clamps for the RC8R. I tried to get Nichols to take on our new project like they did for our Superduke, but I couldn't get a rise out of them. Lucky for us though, Dannyboy is very good friends with another super-creative machinist, who thankfully is also very passionate about bikes. Especially modifying them :-).
Enter... John Starks. John is about as big as a Grizzly Bear in stature, and thankfully for us, also in his abilities as a machinist. He grabbed at the challenge of building us a special set of clamps just for our RC8R. And man, did he deliver..
I’ve never made mention of this before but with all the progress we made on our Superduke last year, there was actually still more to come. We hadn't gotten that bike as good as it can be. You see our pushing the forks down into the Nichols top triple clamp (VIDEO) gave us more rake and trail, which was an exceptional improvement to the bike overall, but at the extreme height we ran fastest with it at, it also left our Superduke real tall. What does this matter? Well all that height, coupled with my "Bull in a China Shop" riding style, made throwing our bike from one side to the next slightly unsettling. In fact through turn 9 at Infineon, which is a second gear violent switchback right-to-left chicane, we felt the affects of running so tall the worst. Landing that bike on it’s side through that chicane in a heated battle in F-1 was like being thrown out the front windshield of a school bus and into a speeding train coming in the opposite direction... But this setting was where the bike worked best everywhere else, so we took that chicane on the chin.. For the new bike though, in an effort to avoid imprinting the same tall trait on our RC8R, we followed a tip which came directly from the world of digital beeps and numbers – instead of pushing our forks down into it's triple clamps to get over 100mm of trail, we asked John Starks to change the offset on our triple clamps from 28mm, to 24mm - which effectively (and this is a quote) "Will do the same thing...."
What’s the big deal right? "The end result is the same.” And if you know a wizard like John Starks, hell why wouldn’t you change your offset to chase those sweet numbers…? Well I’ll tell you why -
“Smashed bike. Angry people. Blood all over the place.”
If not for the fact that I am older now, smarter, and better looking – for sure our RC8R would be a pile of twisted metal today. For sure I’d be bloody. And for sure Mike would be "Angry people".
There is a fascinating reason why changing your offset definitely does NOT produce the same thing as pushing your forks down – even though both changes may share the same goal. There is a fascinating reason why chasing all these numbers is surely relevant, but can also be misleading. There is a fascinating reason why lazy steering couples itself with stability, and quick steering couples itself with head-shakes. First let me say Doug Chandler deserves all the credit for the knowledge I am about to attempt to share with you.
On paper, on the computer, and in the words of some really experienced chassis people - the trail number we were trying to reach (105mm) was a very good number. This would steady our bike at speed, keep us from tucking the front, and give far better feel while leaned over in a turn. Where it all went wrong, ironically, is where it all went right. THAT is the conundrum. No one, of all the people I asked, ever mentioned a downside to changing our offset from 28mm to 24mm. Far as I knew, and if you ask me - far as anyone I asked knew either, this would only make our bike better. But it didn't did it. In fact it made our bike worse. .....A lot worse.
Doug and I are the same age. We've both been roadracing since 88. And we both are tall. That's about as close as I can hang with him. He's better than me just about everywhere else. He's even smarter, which pisses me off because I really try hard to understand all this crap. So I paid him, for what - I had no idea. I just paid him. He stood over our RC8R, he watched it not move, he held it's bars in his hands without ever starting it. And he never spoke a word. Right then I turned and asked myself, "You sure this was a good idea?"
After a bit Doug looked up at me squinting, like the sun was in his eyes (but we were inside) and said, "It's really close, GoGo. .... I bet it's unstable".
Alright WTF am I missing here? How is it I can talk to chassis people, theorize with people sitting in front of computers and digital measuring machines, get special parts made, drive all over the planet building bikes, race all over America for two decades, and run this dam RC8R out on the track last Saturday and not be able to say "Oh, Mary, isn't it so close? Won't it shake it's head going into Riverside?"
I mean Jesus Christ. He didn't even start the motorcycle, never mind ride it. How can he know something like that? ....Well here's how he can know something like that. He got off the bike, walked me over to it, and explained how chassis guys mostly consider bikes from their profile. A better way to think about it, he said, is from above. Then he began motioning with his hands, drawing arcs in the open air, talking about offsets and trail and stressing the need to consider all these things while the bike is leaned over, from above, instead of standing straight - from it's side.
Well holy shit.. Suddenly things started to click for me. Think about it - draw a line through your steering stem, then draw a line through your front axle - both lines parallel, both from left to right. The farther these two lines are from one another, the steadier your bike will be. The lazier your bike will steer. The Closer these two lines are to one another, the more nervous it will feel. The quicker it will steer.
THAT is the hidden difference that changing your offset creates. THAT is the conundrum. We changed our offset to get more trail, in order to gain stability. We did gain more trail, but we LOST stability...
Now imagine this - visualize your bike leaned over - in a turn. Picture one version with a very "close" setup (small steering stem to front axle distance - or "short offset"), and picture the other version with a very long setup. Now imagine what has to happen when you turn the bars to tighten up your line. That's right, turning the longer setup effectively lifts the center of the bike off the ground MORE than turning the short setup.
I think the biggest lesson learned here, at least for me, is not necessarily the physics of all this - but instead the process of it. Monday marked the second time DC10 told me NOT to make changes because chassis people tell me to, NOT because it says so in the book, and NOT because it says so on the computer. His idea, and approach, is more natural. He makes changes according to feel. Then once he gets a bike where he likes it, he uses the "numbers" more to maintain that place he likes, rather than to change it.
We should have done that instead. My mistake.
Right now John Starks is modifying the custom triple clamps he made for us, to accept different offset inserts that the steering stem will mount into. This will give us a library of offset options, rather than limiting us to just one pre-set dimension. We actually have Dan Kyle to thank for this idea, and for the insert we are using as a template.