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Offline Noggie

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Re: Anyone re-sprung a DDC bike?
« Reply #100 on: May 12, 2018, 11:01:10 PM »
BMW built this bike for a 85kg rider with gear, so basically the average 75kg person.

The biggest issue with the DDC is that it does not take nicely to different spring rates between front/rear.
I experienced this first hand, when just changing the fork springs the bike became terrible to ride.
Also worth noting is that the DDC and conventional forks have different springs dimension. Very few manufacturers have springs for DDC.
Wilbers have a 8.0nm spring, this is slightly lighter than the stock spring.

Stock spring is 0.85kg/mm = 8,33nm
8.0 nm = 0,816kg/mm
9.0 nm = 0,917kg/mm

I made a change to the 9.0nm and the was significantly stiffer despite being just 0,067kg/mm heavier and suits a 100-115kg rider.
The 8.0nm will be just 0,034kg/mm lighter.
My guess that this might suit someone weighing 60-65kg plus gear.
Any lighter you might have to get custom springs made.

Offline 1964Hall

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Re: Anyone re-sprung a DDC bike?
« Reply #101 on: May 12, 2018, 11:13:34 PM »
*Originally Posted by Noggie [+]
BMW built this bike for a 85kg rider with gear, so basically the average 75kg person.

The biggest issue with the DDC is that it does not take nicely to different spring rates between front/rear.
I experienced this first hand, when just changing the fork springs the bike became terrible to ride.
Also worth noting is that the DDC and conventional forks have different springs dimension. Very few manufacturers have springs for DDC.
Wilbers have a 8.0nm spring, this is slightly lighter than the stock spring.

Stock spring is 0.85kg/mm = 8,33nm
8.0 nm = 0,816kg/mm
9.0 nm = 0,917kg/mm

I made a change to the 9.0nm and the was significantly stiffer despite being just 0,067kg/mm heavier and suits a 100-115kg rider.
The 8.0nm will be just 0,034kg/mm lighter.
My guess that this might suit someone weighing 60-65kg plus gear.
Any lighter you might have to get custom springs made.
This is useful, thanks for posting. Oddly I find the front okay on my bike, I weigh 56kgs + gear (maybe another 10kgs)I actually have a few turns of preload on the front and zip tie on fork slider shows a nice 10 to 15mm gap brfore bottoming out. Actually, I've lost weight since setting that up so might even wind preload off a few turns and recheck ziptie. It's the rear I have problems with, solved by carrying 15kgs of luggage, preload wound right out.
\v/
In the garage...
S1000XR

Offline Noggie

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Re: Anyone re-sprung a DDC bike?
« Reply #102 on: May 12, 2018, 11:36:28 PM »
*Originally Posted by 1964Hall [+]
This is useful, thanks for posting. Oddly I find the front okay on my bike, I weigh 56kgs + gear (maybe another 10kgs)I actually have a few turns of preload on the front and zip tie on fork slider shows a nice 10 to 15mm gap brfore bottoming out. Actually, I've lost weight since setting that up so might even wind preload off a few turns and recheck ziptie. It's the rear I have problems with, solved by carrying 15kgs of luggage, preload wound right out.
\v/

These rates is for the forks.
For the rear you can use any spring, its the same spring for DDC and conventional, -R/-RR/-XR shock.

My problem when just adding stiffer fork springs was that the rear became extremely soft.
The DDC works of computer calculations, and any fork motion is used to adjust the shock. Hit a bump and see large and fast movement on the fork and the shock gets stiffer.
Little and no movement and the shock is soft.
When I put stiff forks springs on my bike the system got confused.
My fork motion was slow/short due to the stiff forks, and the system made the shock soft.
The rear was terrible in corners, the front was great, but the rear compressed a lot with even the slightest throttle input and you got that vague rear feel and a super soft rear end that moved up and down with the slightest push.

Though the lighter spring should hopefully make the rear softer too for a lighter rider.

Offline Garandman

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Re: Anyone re-sprung a DDC bike?
« Reply #103 on: May 28, 2018, 11:44:11 PM »
*Originally Posted by Lowrance [+]
When I was referring to a reputable tuner I was not thinking of Bren Tuning....never used him personally but from what I have gathered (from many forums), the general consensus is the guy is a snake oil salesman.

Although, if someone were willing to give him a try, I would be very interested in the results! :002:  Having said that, I'd be really surprised if this guy has delivered any suspension settings that work (HP4, S1KR or S1KRR).
He tuned my Subaru WRX (a Stage 2 motor with forged pistons, nitrided crank, etc) and had an S1000RR there, but my impression was it was for engine tuning.

Next time Im out that way Ill stop by. Although this thread is making it very unlikely Ill buy an S1000R.

 


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