Handle Bar construction and steering forces / impulse to high? - Ducati Supersport 939 Forum
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post #1 of 34 (permalink) Old 08-14-2019, 06:22 AM Thread Starter
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Handle Bar construction and steering forces / impulse to high?

When I drive narrow, twisty roads with large lean angles (> 42°) and many following curves, I noticed that the necessary steering forces are sometimes quite high. Especially the shifting from one leaning angle to the other is sometimes difficult. I have thought about this at home and have put up the following theory. I would like to introduce them to you and ask for your opinions and experiences.

I've been riding motorcycles since I was 16. After all, that's already 21 years. Just to start with, so you don't think I'm a beginner who just needs to practice a little more. You can never have enough practice, but my feeling tells me that something is going on here.

Our cockpits looks like that:


I would like to draw your attention to the following:
- The handlebars are not mounted as clamps around the fork tubes, but are screwed onto the fork bridge.
- The angle is similar to that of super sporty bikes like the V4S.

Cockpit from the Z1000 SX (Many say that it is the main competitor of our motorcycle):


As you can see, the handlebars are mounted directly to the fork tubes. In addition the angle is much wider, so that the handlebars are much wider. Therefore you can realize much higher leverage forces. The leverage becomes larger by the wider handlebar and at the same time the force is transferred more directly by the mounting on the fork tubes.

Cockpit from the Honda CBR 650 R (in my opinion, biggest competitor):


The handlebars are mounted at about the same angle as on our motorcycle, but just like on the Z1000SX directly on the fork tubes.

My theorie:
The handlebar of Supersport has two disadvantages:
1. mounting from above on the fork bridge, so that forces are transmitted only indirectly
2. the angle is similar to sporty motorcycles and less suitable for touring

Overall, this results in much higher steering impulses, which the driver must carry out in order to move the machine from one leaning position to the other.

What do you think about it?

Is it a solution to mount the Ducabike handlebar stubs? What experience have you had with it? Would you recommend the 2° or the 10° version?

Last edited by ChuXseN; 08-14-2019 at 06:27 AM.
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post #2 of 34 (permalink) Old 08-14-2019, 07:36 AM
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Quote:
Originally Posted by ChuXseN View Post
My theorie:
The handlebar of Supersport has two disadvantages:
1. mounting from above on the fork bridge, so that forces are transmitted only indirectly
2. the angle is similar to sporty motorcycles and less suitable for touring

Overall, this results in much higher steering impulses, which the driver must carry out in order to move the machine from one leaning position to the other.

What do you think about it?

Is it a solution to mount the Ducabike handlebar stubs? What experience have you had with it? Would you recommend the 2° or the 10° version?
I think it’s the tires being different profile and needing more “effort” to hold a line than other tire models do, nothing more.

Your handlebar mounting theory really doesn’t come into play in my opinion because effectively, they all mount to the same place on the bike and at similar angles. So yeah some you show mount direct to the fork tube which is stolidly mounted in the bridge which is where the clip ons mount to on the SS. They control the same thing, the top bridge.

I’ve noticed the Rossi IIIs can take a bit more effort at the more severe lean angles than at the initial turn in, but to me that helps me when I’m leaving the corner to more easily stand the bike upright. I may go with a slightly more sporty model tire when I wear these out but honestly I like the feel, mileage and level of grip I’ve gotten so I may just stay.

Someone has the Ducabike bars and sold them when they sold the bike. No idea who bought them, hopefully they’ll chime in, I think it was the 10 degree one.

Mike

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post #3 of 34 (permalink) Old 08-14-2019, 09:47 AM
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I think your theory about the angle of the handlebar is correct, as in, it's more sporty and harder to steer at extreme lean angles. However, I agree with @Miweber929 , it helps me ride it harder when I'm leaning, definitely gives a more sporty feel. I had a 2005 Monster S4R and took it to track days, it was the easiest thing to flip and largely because of the handlebar being so straight IMO. However, I prefer the SS angles as the bike feels more stable at extreme leans, but that might be just my opinion. Also when you go full throttle in a straight line, the angle allows you to tuck your elbows in more comfortably and I like that position a lot more.

I also like the fact that the handlebars are raised. For everyday riding and for touring it's so much more comfortable IMO. I've once ridden a Monster 900 with clip ons mounted to the forks. Although it looked really good, my back and my wrists were aching after about 20 minutes! There was so much vibration too!

I've only been riding for about 8 years and haven't done too many track days and have only been on long trips 4 times (more than 3 days trips), but in my opinion the SS handlebar position is perfect. Sporty enough for me and definitely comfortable enough too.
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post #4 of 34 (permalink) Old 08-14-2019, 10:56 AM
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For sure leverage will make a big difference. I have flat and wide handlebar conversion on my V11 Sport and it's quicker to steer vs the factory clip ons.

OTOH, I am not sure I've ever a ridden liter bike as quick and easy to steer than the SS. IIRC, we posted a vid comparing it to the 959, VFR and Kaw, and the handling was much livelier.

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post #5 of 34 (permalink) Old 08-14-2019, 12:02 PM
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There are so many factors at play other than the angle of the handle bars. Fork angle, trail, seat position, weight center of gravity, tires (like wiener says) etc all are hugely influential so I’d say if the angle of the bars are a few degrees back or forward should have very little impact on the handling.

True that a wider bar gives you more leverage than the typical narrower sport bike bars and hence possibly more sensitive steering inputs. On the other hand I think has more to do with the the fact that on a sports bike you want your arms to be tucked in behind the fairing when riding fast rather than anything about quick or slow steering inputs (which is mostly about rake and trail anyway, as above). The fact that bars are mounted below or above the triples should have zero impact on leverage but since your body is pushed a bit further back with the bars on the SS, it also means that you have to force yourself forward more to get that aggressive stance that you get “automatically” with lower mounted bars. However, once you hold your torso in a more forward position you likely will see very little diff handling wise. I know that my old SV650S (half fairing budget sport bike) felt much more aggressive than what the SS does since the body position was much more forward leaning but I also had wrist aches after very little time on it.

In my experience, changing the tires from the Rosso III to Metzeler Sportec M7RR made turning quicker, with less force required to initiate or change lean but I also didn’t compare two sets of new tyres so difficult to say if it was just new tires that made the diff. Wouldn’t you want more stable handling when touring though?

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post #6 of 34 (permalink) Old 08-14-2019, 03:42 PM
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I don't want wider handlebars. I agree that wider bars afford more leverage, but narrower bars provide quicker response and are more aerodynamic. A change in handlebars was the first modification I made to my last road bicycle. It is more obvious on a bicycle that narrow bars have and aerodynamic advantage.
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post #7 of 34 (permalink) Old 08-14-2019, 04:49 PM
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Originally Posted by Dino de Laurentiis View Post
There are so many factors at play other than the angle of the handle bars. Fork angle, trail, seat position, weight center of gravity, tires (like wiener says) etc all are hugely influential so I’d say if the angle of the bars are a few degrees back or forward should have very little impact on the handling.

In my experience, changing the tires from the Rosso III to Metzeler Sportec M7RR made turning quicker, with less force required to initiate or change lean but I also didn’t compare two sets of new tyres so difficult to say if it was just new tires that made the diff. Wouldn’t you want more stable handling when touring though?
The Pirellis have a "pointy" profile that is quick to tip in from center, but flatter at the edge, so the input effort will vary depending on where you are "on the tire" and which way you are turning the bar. I got rid of the Pirellis because they would exhibit weird behaviors on turning into off camber turns - the bike felt like it was resisting input. I went with Dunlops which have a particularly round profile and require the same effort to turn in regardless of where you are "on the tire."

Turn in is definitely a function of several geometry numbers on the bike: Steering angle, trail, wheel base, tire size, tire profile, wheel weight and handlebar width.

To the OP's point, the bar attachment isn't as important. But the overall width is - a longer bar gives more leverage, meaning that for the same physical effort the front wheel will rotate more. Alternatively, shorter bars reduce the leverage and prevent over-input from riders, sort of like a poor-mans steering damper. Where those bars attach isn't as important to the function of turning in.
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post #8 of 34 (permalink) Old 08-14-2019, 10:14 PM
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Originally Posted by ChuXseN View Post
...The handlebar of Supersport has two disadvantages:
1. mounting from above on the fork bridge, so that forces are transmitted only indirectly
2. the angle is similar to sporty motorcycles and less suitable for touring...
I think you are wrong in your assessment of the mounting position. It is still a collar going around the fork tube. The only difference is the placement of the fasteners. Also consider the steering pivots around the steering head, not the individual fork tubes.

There should be no difference between the angle of the grips, irrespective of whether the bike is a sportbike or a tourer. The angle of the handgrips should be the same as the angle your hand falls naturally. If the angle is too narrow (for you) you will tend to ride like you have chook wings, elbows pointed up and away from your body. Too great an angle and your elbows are tucked in but you tend to lose leverage.

In an ideal world, we would be able to adjust the angle of the grips. Old school clipons, actually clamped to the fork tubs, allowed this but as mitigation became the curse of the modern world, manufacturers started pinning the clamps so they couldn't rotate, or using some other method that effectively removed adjustability. Similarly, some manufacturers pin the level blocks so you can't rotate the clutch or front brake lever to the correct position for you.

One of the reasons I love the Supersp[ort is the way it fits me. But I understand it doesn't fit everyone. The same can be said for all bikes, and part of the decision to buy a bike should be how much it will cost to make it fit. As you say, there are third party products that can be used to modify the handlebars. But I don't think they'll change the mechanical advantage as much as ergonomically fitting a rider so they can apply effort effectively.

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Last edited by theresanothersteve; 08-14-2019 at 10:16 PM.
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post #9 of 34 (permalink) Old 08-15-2019, 04:20 AM Thread Starter
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Thanks for your feedback!

Apparently I have to reject my theory.

I have also thought about mounting a Metzeler Sportec or Roadtec next. In the beginning I had mounted the Rosso III and changed to the Angel GT 2, but the Pirelli tyres don't seem to be made for my driving style. At least I don't get enough feedback from the tyres. With Metzeler tyres I only had good experiences on my last bikes so far. This might also solve my problem of quickly turning the bike over at high lean angles.

In the next few weeks I will also have a suspension specialist (Oehlins Service Point) adjust my suspension to me.

I will try out the Ducabike handlebars as the last option. I'm still not sure if I should choose the 2° or 10° option.
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post #10 of 34 (permalink) Old 08-15-2019, 04:24 AM
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Quote:
Originally Posted by ChuXseN View Post
I will try out the Ducabike handlebars as the last option. I'm still not sure if I should choose the 2° or 10° option.
I have the 10º Ducabike bars fitted to bring the bars up as well as back. Each bar is 25mm longer than the OEM bars which I don't really like but it could help you with the extra purchase you feel you need.
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