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Discussion Starter #1
Hello, I recently got my hands on a 748s. I know based on a previous recipt, that the steering head was change ".5" I'm not sure if there is a direction, or maybe +/- would indicate that.

Regardless, I've only ridden it once and I've never ridden this gen Superbike before but it was twitchy as hell on the ride into the shop for a look over. When I would lane split up to a stop light, the steering was downright un-ruly in any ruts, or even big thick paint on road strips. I've had a 999, a m750 (with narrow ass clipons) and my current steady is a SC s1000s. And none of them exhibited this massively twitchy behavior.

It's in the shop now for a look over (it had sat a while) and I've asked them to return the steering to "stock" which I guess would be .0?

I'd love to hear some thoughts on this.
 

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Hello, I recently got my hands on a 748s. I know based on a previous recipt, that the steering head was change ".5" I'm not sure if there is a direction, or maybe +/- would indicate that.

Regardless, I've only ridden it once and I've never ridden this gen Superbike before but it was twitchy as hell on the ride into the shop for a look over. When I would lane split up to a stop light, the steering was downright un-ruly in any ruts, or even big thick paint on road strips. I've had a 999, a m750 (with narrow ass clipons) and my current steady is a SC s1000s. And none of them exhibited this massively twitchy behavior.

It's in the shop now for a look over (it had sat a while) and I've asked them to return the steering to "stock" which I guess would be .0?

I'd love to hear some thoughts on this.

Are you saying that the head as cut and rewelded at a different angle the or the configuration of the head tube eccentric was put in the forward position? Generally speaking, if you go to the forward, steeper position, then you would change the triples to suit or else it's a little on the twitchy side. Anyways, it's the latter it's a 5 minute fix.
 

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Discussion Starter #3
Are you saying that the head as cut and rewelded at a different angle the or the configuration of the head tube eccentric was put in the forward position? Generally speaking, if you go to the forward, steeper position, then you would change the triples to suit or else it's a little on the twitchy side. Anyways, it's the latter it's a 5 minute fix.
The eccentric was adjusted .5 degrees whatever that means. So maybe based on the feeling, and stock triples, it's .5 degrees forward.

I've never ridden a bike with adjust ability in this area, is the feeling change MASSIVE?
 

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The eccentric was adjusted .5 degrees whatever that means. So maybe based on the feeling, and stock triples, it's .5 degrees forward.

I've never ridden a bike with adjust ability in this area, is the feeling change MASSIVE?
Well, this can get into a very complicated discussion that's way above my pay grade but here's a stab at some preliminaries.

First, I seem to recall that there's not a .5 adjustment. It's 23.5 or 24.5 degrees (I'm sure someone will correct me if I'm wrong). If it's .5 it's in the middle and that's not an actual setting and would make for a real mess. You can tell if it's forward or back based on where your steering damper is located (assuming someone didn't do a .5 change). Secondly, when you make the adjustment, it should be done in concert with other things - ride height, extended swing arm, different triples, among other things - to make a safe, effective change. Simply changing the head angle on its own and not at least changing the ride heights and suspension settings (let alone lots of other things) is, in my experience, a big no-no.
 

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The central issue with making this change is stability. A motorcycle is designed to return to its straight-ahead condition after hitting an object or bump in the road that causes the front wheel to deflect slightly to the right or left. In other words, it has to remain stable for a variety of road conditions, and motorcycle stability is foremost a safety issue.

The way dynamic stability is assured is to design a bike with enough distance between the point where the front wheel touches the road and the intersection point between the steering axis and the road. This is called the trail dimension.

A longer trail dimension increases the motorcycle's stability on straights, but will also negatively affect the motorcycle's turning effort, i.e., more rider's strength is required in corners and transitions. However, the more trail, the greater the ability of the bike to self-correct it's steering. It's a longer trail dimension, for example, that allows you to easily ride with no hands on some bicycles, but not others.

A shorter trail dimension, on the other hand, produces a lower opposing force to steering inputs. It's kind of like power steering. So the steering requires less rider strength, but larger handlebar displacements from bumps in the road and corners are fed back to the rider. Said another way, the shorter the trail, the more rider input that is needed to hold a line and the more responsive the bike feels since it is more sensitive to steering inputs.

The two superbike steering angle positions, 23°30' and 24°30' produce trail dimensions of 91 mm and 97 mm respectively. The wheelbase, also an important factor in stability, remains unaffected when you change it. As a comparison, the Monster steering angle is fixed at 24° and the trail dimension is 94 mm. Adjusting the trail dimension on most manufacturer's bikes is not an option.

As an aside, when you change to the steeper 23°30' position you loose a significant amount of steering lock making low speed U-turns more difficult. Also, the ignition steering head lock doesn’t engage in the steeper position.

Now, here's Ducati's warning: "Trail should only be altered after all the other (geometry and suspension) changes have been made and you are comfortable on the bike. If the bike displays any instability problems they need to be sorted out first, as this steering head angle change will magnify these characteristics."

(One reason, for example, is that part of its effect mimics changing the rear ride height.)

The Haynes Service manual goes on to say "Warning: The steering head angle must be set to the road position (longer trail) whenever the bike is used on the road. If the steering angle is set to the race position (shorter trail) ... the handling of the machine could become unpredictable on uneven road surfaces."

So, shortening the trail is considered unwise for street riding (unlike tracks) where bumps in corners, potholes and other road hazards repeatedly challenge your bikes steering stability. Here's a case where inexperienced or uninformed riders who set-up their street bike chassis geometry as racebikes are just looking for trouble.

Trying to mimic factory race bike set-ups can get you into trouble. It's central to racing that race bikes often need to sacrifice high-speed stability to handling. Riders may initially run the steeper steering head angle, but often, as they get faster, they realize they want more stability, not less.

To get more stability there are two things that Ducati typically changes on their racebikes: the triple clamps and the swingarm. They use triple clamps with less offset, typically 27 mm instead of the stock 36 mm, and use a 25 mm longer swingarm to increase the wheelbase. These changes to the triple clamps or the swingarm have the effect of moving the center of gravity forward which is the typical starting geometry of the Corsa race bikes.
 

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Discussion Starter #6 (Edited)
Ok wow, thank you both for the detailed response, I knew I could count on the Ducati.ms Cabal to come to my rescue.

While pushing it around the garage I did notice how shit the turning radius was. But never owning one before, I just thought it was normal. Also, the steering lock does not engage and the steering damper is placed in the "rearward" position.

So for sure the steering head angle is in the steeper setting. I seriously doubt it has a longer swing arm. There are a few safety wired parts on the bike so I imagine it was a track day toy for at least 2000 of it's 7000 miles.

With new tires and putting the steering back to stock geometry I imagine it will handle much more like I'd expect.

I'll start my search for ride height settings, looks like about 1/2 inch of fork is visible above the top tripple. I have no idea what the rear is set at but I'll measure all this stuff when I pick'r up tomorrow.

I think you can see in the photo that the head is in the forward position. I assume those are stock triples, I don't think there are those stock factory looking ones in the offset.
 

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Ok wow, thank you both for the detailed response, I knew I could count on the Ducati.ms Cabal to come to my rescue.

While pushing it around the garage I did notice how shit the turning radius was. But never owning one before, I just thought it was normal. Also, the steering lock does not engage and the steering damper is placed in the "rearward" position.

So for sure the steering head angle is in the steeper setting. I seriously doubt it has a longer swing arm. There are a few safety wired parts on the bike so I imagine it was a track day toy for at least 2000 of it's 7000 miles.

With new tires and putting the steering back to stock geometry I imagine it will handle much more like I'd expect.

I'll start my search for ride height settings, looks like about 1/2 inch of fork is visible above the top tripple. I have no idea what the rear is set at but I'll measure all this stuff when I pick'r up tomorrow.

I think you can see in the photo that the head is in the forward position. I assume those are stock triples, I don't think there are those stock factory looking ones in the offset.
Something else must be off because in that pic, that's in the "stock" setting as it's delivered for road use. Also, the steering lock should work in that position.

Someone way smarter than I am will chime in shortly suggestions with where to look, starting with the basics like tire pressure...
 

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Discussion Starter #8
looking at this thread I'm pretty sure mine is in the forward position, without having the steering damper properly adjusted. The last time the bike was seen by a shop was in 2006, on that recipt it talks about the steering head angle change. So hopefully it's just an illusion in the photo, as the response of the bike was 100% what every thread (now that I know what to look up, THANKS!) seems to talk about.

Stupid adjustments.....

http://www.ducati.ms/forums/56-supe...head-angle-how-identify-current-position.html
 

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The picture shows the eccentric in the optional steeper position, 23.5 degrees. The standard position is all the way back, 24.5 degrees. There is no in between position.

You do not have to change triple clamps to us the steeper position. Some people choose to use different offset triples for track but it’s a personal choice.

None of this has anything to do with the horrible handing symptoms you describe. Look for something else to be terribly wrong. To be honest it sounds like you’re riding on two flat tires.


Sent from my iPhone using Tapatalk Pro
 

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Stock or as delivered it should be in its most “relaxed” position and the steering lock will work. In its steepest position the steering lock won’t work. You have other issues if you’re bike is trying to kill you at the steepest setting. Check tyres, klickers front and rear, ride height, pre-load, and HEAD BEARINGS.
 

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Discussion Starter #11
The picture shows the eccentric in the optional steeper position, 23.5 degrees. The standard position is all the way back, 24.5 degrees. There is no in between position.

You do not have to change triple clamps to us the steeper position. Some people choose to use different offset triples for track but it’s a personal choice.

None of this has anything to do with the horrible handing symptoms you describe. Look for something else to be terribly wrong. To be honest it sounds like you’re riding on two flat tires.


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I think I am probably just over exaggerating the symptoms. Imagine lane splitting at real low speed, I didn't feel confident as the bike was super interested in tracking with all the groves and crap that happen as you approach stoplights with cars just a few inches either side. Not an issue on the SC, or any other bike I've owned but I gave up on that at the first stoplight I encountered on the 748s.

I'm getting brand new tires, the steering reverted to stock and we'll go from there, but I hope that fixes it.
 

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Discussion Starter #13
I still think mine is in the forward position. I mean the steering lock doesn't work, and the turning radius is crap and it's twitchy. I hope it's the steering and not something CRAZY.

Come on be the steering head angle!!! I mean, maybe it's delivered in this position but regardless, I want it in the back position for stability.
 

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I still think mine is in the forward position. I mean the steering lock doesn't work, and the turning radius is crap and it's twitchy. I hope it's the steering and not something CRAZY.

Come on be the steering head angle!!! I mean, maybe it's delivered in this position but regardless, I want it in the back position for stability.
Well, if my original thought that someone has it in neither position but rather in the middle (i.e. the 0.5) then maybe. But I am not even sure if it can be locked in that halfway position.
 

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Discussion Starter #16

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I still think mine is in the forward position. I mean the steering lock doesn't work, and the turning radius is crap and it's twitchy. I hope it's the steering and not something CRAZY.

Come on be the steering head angle!!! I mean, maybe it's delivered in this position but regardless, I want it in the back position for stability.
Actually looks like it’s set in the “track” position with the damper set in the “road” position to me

 

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Actually looks like it’s set in the “track” position with the damper set in the “road” position to me.
No. (The reason that the damper track/forward position is needed is because the damper will hit the tank if it's left in the road/rear position).
 
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