Gearing Up (or down) 401

[Vintage Veloce]

Interesting... I never thought about the noise. Many years ago I had an aluminum sprocket and it wore very quickly. But I suspect they are much better now!

 

[BISavage]

I am sure it doesn't last as long as a sealed chain on a steel rear sprocket, but it should last as long as the unsealed chain.

I am wondering if I need to adjust the rebound to compensate for the weight loss.

 

[Vintage Veloce]

Well, the sprocket is unsprung weight...

 

[BISavage]

Less weight means I need more dampening to slow it down? Or the other way round...

 

[aitormartin]

Less weight (m) means you need less damping (c) to achieve the same damping ratio (zeta).



But bear in mind that the weight is inside the square root, so a small variation in weight shouldn't really have much effect.

 

[Vintage Veloce]

Also, there is a difference between sprung and unsprung weights effect on the damping... I assume. Not sure how to account for that will the the math.

 

[BISavage]

For sprung weight @aitormartin is absolutely right.

As the unsprung rotating mass, on the opposite end of the spring/dampener has changed, it won't effect the formula and the adjustments which can be set in the garage, it will effect the dynamic performance of the suspension and will probably need to be set for the typical riding conditions; speed and surface.

Might be only marginal with a sprocket, and would first become an issue with lightweight wheels...

 

[aitormartin]

Also, there is a difference between sprung and unsprung weights effect on the damping... I assume. Not sure how to account for that will the the math.

Here you go :




This last formula is the one I mentioned on my last reply, you would have to substitute the critical damping from both cases (Sprung and Unsprung) here.


Of course this is not useful if you dont have a way of meassuring your spring of tire stiffness. But it's good to know what affects what.

All of this is taken from a seminar aimed to FSAE cars, but it would still apply to bikes. If you are interested in the full presentation, it's avaliable Here.

 

[BISavage]

Got it dialed, vs. The driven adventure 16/45 114 link setup, the esjot 15/45 112 link it needed 2 turns preload & 1 click more rebound.

This is how it looked:

 

[Vintage Veloce]

That's good...I was searching all over for my calculator to try out aitormartin's equations!

 

[BISavage]

Algebra shmalgebra.

 

[BISavage]

So, just thinking about what to put on when the current chain come off for cleaning... What about this:

 

[BISavage]

This one looks pretty cool, JT Racelite Aluminum; JTA890

At 335g its pretty light too.

Prolly slap it on real soon like 'cause the 15/47 be plain stuntin'.

 

[Vintage Veloce]

I really like the look of that one!

 

[BISavage]

So here is the Racelite on the bike with the CZ chain:

 

[Vintage Veloce]

Wheels?! (sprocket looks great!)

 

[BISavage]

Yeah, I wanted to be able to run different tires depending on were I was riding, so I got the Husqvarna Wheels (which are the same as a duke 125 / duke 390) and put my semi used Pilots on them... once these tires "lose" about 1.5mm of tread I will put on my new set of 2CT tires which I have been really interested to try.

(I may just get impatient and smoke it down though...)