Official JABBER Thread (Showing off a Prototype from Austria) - Page 47 - RC Groups
Dec 27, 2011, 07:45 AM
Registered User
There have been discussions about the amount of suspension needed for 1/5th Onroadbikes. Heres what I think about it:

Given a "pothole" on the track with a depth of 5mm when you go over it in a straight line: When you drive over this at a leaning angle of 25° this "pothole" is suddenly 12mm deep... and your suspension should still be able to cope with that too ..

### Images

 Dec 27, 2011, 08:32 AM Big thrills w/o hospital bills Nice visual explanation, Edi.. Our track has plenty of that, especially at the end of the front and back straights, both fast entry corners too.. We all blame the bumps on the 1/5 tourers..
 Dec 27, 2011, 03:06 PM Registered User Not sure on that one Edi. maybe your point lost in translation, The pot hole wont gain 7mm depth with the bike lent over it impossable. The surspension might compress and rebound more due to more load being put on it. seems more like the differance in the radias of the tyre from center to the shoulder could be giving this reading. Can you show the formular you used for this please i could be mistaken myself. Last edited by Whitham69; Dec 27, 2011 at 03:13 PM.
 Dec 27, 2011, 03:21 PM Registered User I see what you done, you messure the angle across at 25 degrees, The wheel will drop down only 5mm no matter what angle the bike at, dont forget the laws of gravity. It easyer to measure the other way, put a 5mm block under the tyre while up right, it measure 5mm, now at 25 Degrees angle the tyre still 5mm off the floor. it same for the hole, Basically the contact point always going to be at the lowest point of the tyre, not on the angle. Last edited by Whitham69; Dec 27, 2011 at 03:38 PM.
Dec 27, 2011, 05:27 PM
Registered User
I think what he was trying to say is that to get 5mm of vertical travel on the tyre when the bike it lent over (so the point of contact between the tyre and track remains constant) the suspension must either compress or extend by 12mm.
However if you are relying purely on the suspension travel during cornering to absorb bumps then this will create a horizontal displacement of the wheel from a vertical disturbence. This is why I have always designed some torsional flexability into my bikes so that when cornering the flex in the chassis is allowing the wheel to move over bumps without creating any horizonal movement.

### Images

 Dec 27, 2011, 06:33 PM Registered User that make more sense, thought something was lost in translation. Maths is correct but I still dont think it 100% correct formuler for working this out. like you say your still going to get vetical movment of the bike which will lower the suspenstion travel movement need and tyre deformation would effect it plus the flex in the chassie and forks. The maths is just to simple for motorbike. Last edited by Whitham69; Dec 27, 2011 at 06:43 PM.
 Dec 28, 2011, 06:24 AM Registered User Just look at the picture I didnt do any maths. Maths is not really needed on Bikes because bikes are really primitive... a little bit of common sense helps you out of most of your "problems" .. for example a bike ( I mean a really fast 1/5th scale bike) "pulls" up to 2.5Gs in a turn... then "your vertical" is my "25° leaning angle". And when I go through a turn at 25°/65° I am NOT doing that with the scratchbars touching ground *giggle*.
 Dec 28, 2011, 11:03 AM Registered User Thank you for all the information in your thread Edi. Even though the bike I'm building is far behind the "tech" you have in yours, I learn allot in here. So would you say 24mm of rear suspension travel is a good place to start?
Dec 28, 2011, 03:09 PM
Registered User
Quote:
 Originally Posted by edi.winter Just look at the picture I didnt do any maths. .
i notice you never it why the answer of 12 is misleading, it one dimensional thinking. Try adding just one other factor of many time, How long it takes to rebound or compress 12mm to the time taken for a really fast bike to travel over a 5mm pothole.

no disrespect it not as simple as you think

Quote:
 Originally Posted by edi.winter I am NOT doing that with the scratchbars touching ground *giggle*..
Dec 29, 2011, 03:15 AM
Registered User
Quote:
 Originally Posted by ray schrauwen Thank you for all the information in your thread Edi. Even though the bike I'm building is far behind the "tech" you have in yours, I learn allot in here. So would you say 24mm of rear suspension travel is a good place to start?
16mm Front and 25mm Rear is about right...
Dec 29, 2011, 12:32 PM
Registered User
I have been posting a lot of information on Facebook but still there are a lot checking out whats happening here

I have finished the 2012 and started ordering the parts. I hope its not a hell of money wasted .... on second thought: IT IS A WASTE of MONEY!! still I luv it.

On the Front view you see the max. leaning angle of 16°/74° and the practical leaning angle of approx.23°/67°.

The other is just a overall view. I am still shading it a bit. Not because I really do not want you to see it. Its more because I am not sure if it works. I do not want to mislead the community with non functioning solutions. Once its up and running and is making a goodish figure on the track its free to see

### Images

 Dec 29, 2011, 12:41 PM I'm hooked on RC Moto The picture is still a little blurry. Could you fix that?
 Dec 29, 2011, 12:45 PM Registered User If you stare at it long enough and have a few beers in the process you wont notice the blurryness after a while
Dec 29, 2011, 05:10 PM
Registered User
Quote:
 Originally Posted by edi.winter 16mm Front and 25mm Rear is about right...
Thank you MUCH
Dec 30, 2011, 08:41 AM
Registered User
Quote:
 Originally Posted by edi.winter If you stare at it long enough and have a few beers in the process you wont notice the blurryness after a while
I like your way of thinking Edi.

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