racebike fork height?

Randy Grein randygrein at comcast.net
Sun Jul 6 23:18:34 PDT 2008

Rear height is more than just turn-in, it affects spin-up, overall  
height, etc. The 14mm number is what most of the fast riders have  
found works with the first gen naked bikes - the S model forks are a  
bit different length; I'm not sure what's needed there. In any case,  
raising the rear affects the turn-in less than dropping the forks. The  
whole thing is explained in Max Macallister's video 'Suspension Tuning  
for Mortals', still being sold over at traxxion.com.

You're almost right about why the GSXR forks feel fine, but I believe  
it's not rake, but trail - which is mostly set by the triple clamps.  
However, I haven't actually measured, so if anyone knows better I'll  
defer to a real measurement.

Randy Grein, WMRRA #41

On Jul 5, 2008, at 11:39 AM, Ulrich Wiedmann wrote:

> Haven't seen it mentioned yet: I'm not 100% sure about this, but I  
> thought
> all Penske shocks are height-adjustable.
> You can get the quicker turn-in as well by raising the rear. The  
> nice thing
> about the Penske's is that this is a really easy thing to do - so  
> you can do
> some trial & error at the track.
> W.r.t. the GSXR forks & length - Doesn't the rake of the forks vary  
> from
> stock after the mod? This would mean that it's not really an
> apples-to-apples comparison. i.e., despite the fact that the forks  
> are 1"
> shorter, it's not the same as lowering the stock forks 1".
> -- Ulrich
> On Thu, Jul 3, 2008 at 6:19 PM, Randy Grein <randygrein at comcast.net>  
> wrote:
>> I did it for several years. Not bad, but the competition wasn't as  
>> stiff as
>> it is now.
>> You're  just my size Roger, and the .85 springs should do you well.  
>> As to
>> fork drop you should end up around 14 mm - this is primarily due to  
>> the
>> increased ride height from stock.  That is, if the 2nd gen naked  
>> forks are
>> the same as the 1st gen. At 14 mm they JUST miss touching the lower  
>> triple.
>> Funny thing is the GSXR forks are over an inch shorter and feel  
>> great.
>> Randy Grein, WMRRA #41
>> On Jul 3, 2008, at 12:46 PM, Roger Gonzalez wrote:
>> Yep, stock triple clamps for the naked.  And yes, I have the Penske  
>> rear -
>>> can't imagine riding without it.  :-)
>>> I'll give 10mm a try this weekend.
>>> Thanks,
>>> -rg
>>> Steve Robertson wrote:
>>>> 10mm may be a relatively big change from where you are currently at
>>>> but many racers run that and more. Nothing wrong with going 5mm at
>>>> a time to let yourself adjust, but the number he suggested isn't  
>>>> radical
>>>> at
>>>> all. Are you running your stock triple clamps or some off of a  
>>>> "S"? If
>>>> you
>>>> are running stockers you also have more trail than an "S" to  
>>>> start with
>>>> so
>>>> 10mm would be fine. You may end up going even more. At 210lbs I  
>>>> hope
>>>> you have an aftermarket shock (or plan to get one!)
>>>> Steve
>>>>> I have the racetech front end in my 2003 650N and I'm installing
>>>>> .95kg/mm springs today. (was at .90 - I'm 210# w/o gear)  I've  
>>>>> been running
>>>>> with the caps level with the top of the bracket (I think that is  
>>>>> the stock
>>>>> position?) but a suspension guy I talked to recommended 10mm of  
>>>>> tube above
>>>>> the triple.  That seems like a pretty big change to me; I might  
>>>>> just try 5mm
>>>>> and see how it feels.  Thoughts?
>>>>> Not looking forward to roasting at Thunderhill this weekend,
>>>>> -rg

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