Changing gearing -- front vs rear

Randy Grein randygrein at comcast.net
Tue Jun 24 21:15:45 PDT 2008


Um, yeah. Industrial designs also underload chain & sprocket rigs  
compared to bikes by a factor of 10 or more IIRC. Bikes are a serious  
mechanical compromise, this is just one area.

Another issue, or used to be is the chain angle. The ideal is to get  
the countershaft as close to the swingarm pivot as possible, and  
equalize the sprocket sizes to eliminate chain pull on the swingarm. A  
mid-80's Bimota design had an extra wide swingarm that used  
freestanding outboard pivot points concentric with the countershaft.  
Chain slop was minimal and didn't vary throughout wheel travel.  
Complex and heavy though.


Randy Grein, WMRRA #41

On Jun 24, 2008, at 7:26 AM, Kabara, Richard M. wrote:

> I looked up some stuff last night...
> The book I was referring to "The Racing Motorcycle, A technical  
> guide for
> constructors" John Bradley. He claims "Industrial designers try to  
> avoid
> anything less than 17 teeth"
>
> Two data points on OEM stock c/s sprockets that I have in my garage...
> 2003 R6 - 16 tooth
> 2006 GSX-R750 - 17 tooth
>
> These are 'cutting edge' sportbikes where weight and compact design  
> are
> critical, still they use 'big' c/s sprockets. Of course they set the
> internal ratios to work with those sprockets, would not work on  
> SV...or rear
> sprocket would have to be unreasonably large.
>
> Moral of the story is: for long term sprocket wear, bigger is  
> better. So if
> you want to shorten your gearing, run 15/48, not 14/45. As Jim already
> proved with his 15 tooth c/s sprocket going for four years.
>
>
> -----Original Message-----
> From: Kabara, Richard M. [mailto:richard.kabara at pw.utc.com]
> Sent: Monday, June 23, 2008 5:41 PM
> To: Suzuki SV650 Mailing List
> Subject: RE: Changing gearing -- front vs rear
>
> Thanks Zoran, it's 520
>
>> From the RK chain website, comparing their "standard O-ring" chains
> http://www.rk-excel.co.jp/global/chain/chain_application.pdf
>
> 520 is 3.36  lbs / 100 links
>
> 525 is 4.30  lbs / 100 links
>
>
> So the 525 is 28% heavier.....I'd call that significantly heavier!
>
>
>
> -----Original Message-----
> From: zoran [mailto:zv30 at sbcglobal.net]
> Sent: Monday, June 23, 2008 5:24 PM
> To: Suzuki SV650 Mailing List
> Subject: Re: Changing gearing -- front vs rear
>
> 520.
>
>
> Zoran Vujasinovic
> Twin Works Factory
> 775-786-4881
> www.twfracing.com
> ----- Original Message -----
> From: "Kabara, Richard M." <richard.kabara at pw.utc.com>
> To: "Suzuki SV650 Mailing List" <sv650 at micapeak.com>
> Sent: Monday, June 23, 2008 2:26 PM
> Subject: RE: Changing gearing -- front vs rear
>
>
>> I'd bet the SV400 uses a lightweight chain, like a 418? (not sure  
>> of the
>> spec) not the heavier 525 chain the SV650 uses, so the SV400 may be  
>> more
>> tolerant of the 14 tooth c/s sprocket.
>>
>> Rich
>>
>> -----Original Message-----
>> From: Jim Stewart [mailto:js at strappe.com]
>>
>> Well, Zoran tells us that the SV 400 has a 14 tooth sprocket stock.



More information about the SV650 mailing list