RC51 Forums banner

1 - 15 of 15 Posts

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #1
Rolled my RC out on a perfectly leveled surface, having the chance to take one more picture of it :D , .... ....



.....my bathroom scale and my camera.
The scale is tricky cause once it stabilizes on a number, it shuts off automatically after 5-6 seconds.
So the numbers may be of a couple of pounds, but they will give us a ball park of the idea. After all, personally I don't care for a couple of pounds difference on the weight of my RC, since I don't race it.

So I put the scale underneath the rear wheel, with the front wheel touching the ground (no front stand)



Then I tighten the bike to an upright position, minding the belt not to lift or pushing it downwards





This is what I got

 

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #3
Put the scale underneath the rear tire



and removed the rear stand



Almost 4 lbs heavier by lifting the front wheel for like 5mm! ! ! !

Then I measure the front.

Unfortunately the scale couldn't fit inside the stand so I had to measure it without the stands, just by balancing it to an upright position again. And I got this



So summing up the results:

Rear without stands



Rear with front stand on



Front without stands



I guess I would read a lot more than 4 extra lbs on the front, if the scale could fit inside the stand, since the rear stand lifts the bike a lot more than 5mm
 

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #4 (Edited)
So, using a paddock stand, proved to be messing with the measurements as expected.

If I add the two numbers I got without the stand, it's

235.2lbs (106.68kg) + 231lbs (104.77kg) = 466.2lbs (211.45kg)

That number makes total sense to me, since my bike has all the fluids in it and a full tank to the cap (18lit)

What do you guys think?

P.S> I still don't get it, why the rear is heavier than the front :confused: :confused:
 

·
Registered
Joined
·
284 Posts
I did the, almost, same couple days ago. Only I bought a second scale (on sale 16USD) and put it on both at the same time.
Did the weighing twice and got 1kg difference, so the scales arent THAT precise.

As to the weight distribution (Ive just asked this question on another topic - what is the f/r bias on a standard SP1?)

Your difference is less that 2kg - thats less than 1kg front and rear out of little more than 100kg - so little less than 1% - which if you weight multiple times might change around.

Why the rear is heavier than the front? In your case it's not much - but remember behind the engine you also got the tail, massive swingarm, wider rim, begger wheel, chain, exhausts, compared to in front the forks and smaller wheel and rim.

You got 50,5% rear and 49,5% front - its pretty damn close.
Ive got 49,9% rear and 50,1% front - still pretty damn close.
 

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #6
Lowering the triples on the front shifts the weight forward. Don't know how much cause I didn't scale the bike when I was adjusting the triple height.
However the bike steers much worse if I lower the triple two lines lower that where it is now.
Makes me think if having a front shifted weight is actually better or not.

With the weight distribution I have now, I totally "feel" the bike when it leans and my steering feels quite "light".
Maybe I haven't learn to lean as I should and this "wrong" setting (rear shifted weight) fits my "wrong" way of riding......

I have a lot of experiments to complete if I want to have a solid answer to any of those questions.

Hanberg, thank you very much for sharing your numbers....helps a lot buddy :)
 

·
Registered
Joined
·
284 Posts
Your welcome.

In your first setup, with the bike supported by a strap, this will take weight of the wheels. I dont know how much your bike was supported by it, but considering you felt it was safe with only one strap, I would guess some.
You need to balance it, maybe have a friend balance it while you watch the scales.
You can test this by putting a bottle of water on a kitchen scale, weigh it, and then weight it again leaning against something.

Also, people talk about lowering the front as putting more weight on the front.
This is right in theory, but we are talking miniscule amounts, and the much more drastic change in geometry will completely cover the change in weight.
What you feel is change in geometry, not weight change.
 

·
Registered
Joined
·
284 Posts
If you want to play around with the weight distribution, you would need to move heavy stuff around - relocate battery to the front is an obvious example to put weight forward.
Or move the entire bikes weight relative to the wheels, but now we are talking rake and different swingarm and big $$$ not to mention the geometry will also change dramatically.
 

·
Registered
Joined
·
162 Posts
I did the, almost, same couple days ago. Only I bought a second scale (on sale 16USD) and put it on both at the same time.
Did the weighing twice and got 1kg difference, so the scales arent THAT precise.
You might find the 2nd time you loaded it up on the scales you hit the brake a bit harder than the first time loading the front/rear suspension differently, that's where I'd say the 1kg swing could be.
 

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #10
In your first setup, with the bike supported by a strap, this will take weight of the wheels. I dont know how much your bike was supported by it, but considering you felt it was safe with only one strap, I would guess some.
You need to balance it, maybe have a friend balance it while you watch the scales.
You can test this by putting a bottle of water on a kitchen scale, weigh it, and then weight it again leaning against something.
I've made sure this wasn't the case. The belt didn't push or pull the bike at all. The way you see it in the picture was barely standing upright, in a way that if I push it very lightly on the left side with just one finger, the bike would lean over towards the belt and fell over.
That's why I said "it was tricky with the scale" cause it took me a while to balance it and I didn't have the time I needed to take a picture of the scale's number. The scale was already shut off. Balancing the bike at a precise upright position is very tricky.

Also, people talk about lowering the front as putting more weight on the front.
This is right in theory, but we are talking minuscule amounts, and the much more drastic change in geometry will completely cover the change in weight.
What you feel is change in geometry, not weight change.
I am aware of those improvements, but the whole experiment, started under the assumption that the RC51 is pure breed superbike. By definition that means that it is a more forward weight distributed balanced bike than others.
And that is what surprises me the most
 

·
Premium Member
Joined
·
3,239 Posts
Discussion Starter #12
Theoretically speaking, if the bike is upright so it's weight force is applied completely on it's vertical axis, it's mass (and not weight cause that is a force) will be the same with it's suspension loaded or not.

However, using a paddock stand, changes things.

Focusing on the rear wheel for example.......



The mass measured on the scale under the rear wheel, is only a part of the total mass (Fgrav).
The bikes weight is divided through it's whole structure ending up on two main forces running through each wheel vertically towards the ground.

What we measure at the scale is the F1 force on the picture.
The F2 is transferred through the bike's chasis to the front wheel and the same thing happens on the front wheel towards the rear.

So when I lift the front end with a paddock stand, the F1 on the front wheel is decreasing and part of it is added to the F2.
The F2 transferred through the bike's chassis is being added to the rear wheel's F1.
Considering now that the rear wheel's F2 is decreasing as well due to the angle change, the amount of the force that is taken from that F2 is added to the rear wheel's F1 as well.

That's why, a slight lift of 5mm on the front wheel, causes the scale to measure 4lbs more on the rear.

Imagine that we could start lifting the bike's front wheel all the way to the vertical position of the bike (the perfect wheelie). Now the scale under the rear wheel would show us the bike's total mass on it's display
 

·
Registered
Joined
·
284 Posts
I agree to you 100% - my question was more a comment to weegaz22

You might find the 2nd time you loaded it up on the scales you hit the brake a bit harder than the first time loading the front/rear suspension differently, that's where I'd say the 1kg swing could be.
I might have been unclear, but the 1kg difference I got was was the overall weight - which wouldnt change no matter how you angle the bike :)

Oh found some numbers online:
Ducati 1098S 434 - 49.6F/50.4R
Honda CBR1000RR 450 - 51.6F/48.4R
Kawasaki ZX-10R 451 - 51.0F/49.0R
Yamaha YZF-R1 459 - 51.9F/48.1R
Suzuki GSX-R1000 466 - 50.7F/49.3R
MV Augusta F-1000R 478 - 51.7F/48.3R

So Ive though their bias is towards the front, we're not talking much.
 

·
Registered
Joined
·
20 Posts
Several months ago I needed to take my front forks out,and tried to lift the front of the bike with a jack at the most forward part of the engine and guess what? The rear of the bike lifted and I had to use a barbell weight to hold the rear down.
I realised then that these bikes are weighted more in the front, thanks for the figures hannberg,good info to know.
lowering the front end makes most if not all bikes steer much quicker every time I've tried it,sometimes it can have a very negative effect.

Like hannberg lowering the front is changing the geometry I beleive.
 

·
Registered
Joined
·
162 Posts
I agree to you 100% - my question was more a comment to weegaz22



I might have been unclear, but the 1kg difference I got was was the overall weight - which wouldnt change no matter how you angle the bike :)

Oh found some numbers online:
Ducati 1098S 434 - 49.6F/50.4R
Honda CBR1000RR 450 - 51.6F/48.4R
Kawasaki ZX-10R 451 - 51.0F/49.0R
Yamaha YZF-R1 459 - 51.9F/48.1R
Suzuki GSX-R1000 466 - 50.7F/49.3R
MV Augusta F-1000R 478 - 51.7F/48.3R

So Ive though their bias is towards the front, we're not talking much.
Yes as you said above i had taken the 1kg difference as a front/rear ratio difference not the overall weight of the bike itself.
 
1 - 15 of 15 Posts
Top