The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Breezerider on November 05, 2008, 09:30:50 PM

Title: Changing rear shock length for better handling?
Post by: Breezerider on November 05, 2008, 09:30:50 PM
I was wondering if adding 10mm (3/8") to the length of the rear shock would make the R65 handle a bit more nimbly?

Title: Re: Changing rear shock length for better handling
Post by: Rob Valdez 79 R65 on November 05, 2008, 10:17:27 PM
[size=12]Have you checked your tire pressure/size, etc.?  Too wide a profile will slow handling (esp. front).  90/90-18s recommended.  It is getting hard to find anything smaller than 100/90-18 these days.

I run 36 lbs f/r solo in my Bridgestone S11's.
The air pressures on the label under the seat are out of date and should not be used.


A cheaper test might be to drop the yokes on the forks a bit.


BE CAREFUL.[/size]
Title: Re: Changing rear shock length for better handling
Post by: montmil on November 07, 2008, 05:40:41 AM
Quote
I was wondering if adding 10mm (3/8") to the length of the rear shock would make the R65 handle a bit more nimbly?


That will alter the angle of trail in the front forks. Thinking of doing a bit of flat tracking on the weekends? Rather quicken up the steering and all that...  

Like Rob sez, "Be careful"

Monte
Title: Re: Changing rear shock length for better handling
Post by: Breezerider on November 07, 2008, 11:09:09 PM
Thanks guys,

My tires are the original stock tires with the correct pressure.  This bike had super low miles when I bought it.  I think I'll stick with the stock length but go to something a bit more progressive.  The bikes stock shocks are sprung for a heavier rider than myself even at their lightest setting and the ride is very stiff.  I'll live with the heavy steering.
Title: Re: Changing rear shock length for better handling
Post by: Rob Valdez 79 R65 on November 07, 2008, 11:21:26 PM
[size=12]If I am reading you right, the bike has THE ORIGINAL tires on it from when it left the factory?

Please say no.[/size]
Title: Re: Changing rear shock length for better handling
Post by: steve hawkins on November 10, 2008, 06:20:59 AM
Try riding around with yours shocks on full preload first.  If that is not enough, try dropping your fork stantions through the yokes (triple trees) by a cm and see if that has the desired effect.

Both options are 'free' and you can have a combination of both.  You will be reducing the rake/trail, moving the c of g and reducing the wheel base.  

Best done a little at a time.

Cheers
Title: Re: Changing rear shock length for better handling
Post by: Breezerider on November 13, 2008, 07:18:32 PM
Quote
Try riding around with yours shocks on full preload first.  If that is not enough, try dropping your fork stantions through the yokes (triple trees) by a cm and see if that has the desired effect.

By full preload you mean set for the heaviest rider?  That's going to be real stiff and stiffness is the problem.

I don't want to mess with the geometry and handling other than softening the ride.  The shock supply guy had a cheaper set that were 10mm shorter and I wanted to know if it would be cool to use them.  But I've decided to stay stock with them.  The other day I went shopping on the bike and had 30 lbs of groceries in the panniers and that softened the ride noticeably.  I think lighter springs are the ticket.

Title: Re: Changing rear shock length for better handling
Post by: Breezerider on November 13, 2008, 07:24:40 PM
Quote
[size=12]If I am reading you right, the bike has THE ORIGINAL tires on it from when it left the factory?

Please say no.[/size]

Heh, I got no reason to think otherwise.  The bike had 20k original miles on it and was stored indoors for years.  The tires are in great shape, but look to be stock.  
Title: Re: Changing rear shock length for better handling
Post by: steve hawkins on November 14, 2008, 03:17:08 AM
Sorry I meant full extension, not full preload.

Jacking up the back will quicken the steering, as will reducing the ride hieght at the front.  However the R65 already has a reputation for being relatively agile when compared to its larger brothers.

What shocks have you got?

If they are the originals, they will be pretty soggy in short order.

Otherwise I would go for a lighter spring of the same length.  But you will need to talk to a specialist to source it.  

Standard Konis/Ikons are definately stiffer.  But you can get a different spring for them.

Steve H
Title: Re: Changing rear shock length for better handling
Post by: Rob Valdez 79 R65 on November 14, 2008, 08:42:24 PM
I recommend fresh tires and shocks, then get back to us.

And put AT LEAST 35 lbs of air in them (the new ones).


Here is some reading on shocks:
http://suraklyn.com/yabb/YaBB.pl?num=1222613889/2#2