Motorcycle Sprokets with More or Less Teeth

 2006 Honda Shadow 600.

Just out of curiosity ...

I think my motorcycle as 16 teeth in the front and 44 in the back.  Where
would I get sprockets with different numbers of teeth?

Also, I'd like to experiment with upping my gear ratio about 10%.  16/44 is
0.3636, so I would see a target of 0.4.  17/43 seems like it might do it ...

Thanks.

--
David T. Ashley              (dta@e3ft.com)
http://www.e3ft.com           (Consulting Home Page)
http://www.dtashley.com       (Personal Home Page)
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http://www.shopmawonline.com/shop.htm

They have links to the Tucker Rocky and Parts Unlimited street
catalogs.

Also try www.denniskirk.com and even www.jcwhitney.com

Does your bike have a 4-speed transmission? It's possible that the RPM
drops 20% when you shift from 3rd to 4th, in which case a 10% gearing
change makes sense.

But the typical standard or sportbike motorcycle transmission has gear
spacings that drop the RPM about 15% as you shift from 4th to 5th or
5th to 6th.

You would generally want to change the gearing no more than 7.5% in
that situation, or you would find yourself downshifting back to 4th of
5th frequently.

�16/44 is

We usually divide the number of teeth in the large sprocket by the
number of teeth in the small sprocket.

44/16 = 2.75:1

43/17 = 2.53:1

That's close to the right amount of final drive change to reduce your
RPM by about 8% while cruising in top gear.

It makes good sense to use sprockets with odd numbers of teeth,
because they wear more evenly. You'll see wear distinct patterns on
pairs of teeth on the final drive sprocket when you use sprockets with
even numbers of teeth.

 
My intuition tells me that the even number of teeth might not be the sole
issue.

Intuition tells me that you want coprimality between the number of links in
the chain and the number of teeth on both sprockets.

http://en.wikipedia.org/wiki/Coprime

My rear sprocket has 44 teeth (I think), my front has 16, and my chain has
120 links.

16 = 2 * 2 * 2 * 2

44 = 2 * 2 * 11.

120 = 2 * 2 * 2*  3 * 5

I'm not sure (I'd have to think about it), but I think if you don't have
coprimality that each link on the chain only visits a subset of the sprocket
notches over its entire life.

This is just me rambling ... I haven't had a lot of time to think about it.

So, for example, it might be the case that if your chain had 119 links and
your sprocket had an even number of teeth that shared no prime factors with
119 that it would wear evenly.

 David T. Ashley wrote:

Uh, why didn't you spring for the Moebius chain?   Besides the coprimal
link count, it's installed in a figure 8 pattern with a half twist.
That way you wear the top, bottom, left, and right of each link equally.
 Plus it makes you go backwards.

 Dnia 2008-10-16 timeOday napisa³(a):

Moebius chains don't have tops and bottoms.  ;-)

--
Andrzej Rosa