4/23/13

Matt Snook

Wheel Travel (WT, spec)

Stroke

Length

(Length is eye center to center, mount length)

STOCK:

Travel/Stroke ratio = 3.4:1

09 Xcountry

165

320*

*Nominal lollipop adjustment, can go +- 10mm

07 Xcountry

210

333*

*Nominal lollipop adjustment, can go +- 10mm

07 Xmoto

245

07 XChallenge

270

345*

*Measured. (But it sags a lot more than Ohlins.)

Ohlins S46HR1C1:

BM 633 (Xmoto)

247**

343

**Travel would be 37 more than 07 stock XCountry (11*3.4)

BM 636 (Xchallenge)

305**

360

**Travel would be 95 more than 07 stock XCountry (28*3.4)

Options: Get Ohlins with length of 333 which would have stroke of 61 and match the Xcountry:

or Use BM 636 (easier to get than BM 633) and add shims to reduce stroke (and length) by 28mm, resulting in:

210***

332

***Calculated

Xmoto shock was on closeout for $495, some people have installed it into an Xchallenge to lower seat height and travel

***********************

I ended up ordering a Wilbers 642-0837 shock in black with the following CUSTOM specs, and the optional ride height adjustment of +0 / -10mm:

Wilbers 642 standard (not mi

192

333

***WT is calculated. Length adjustable to: +- 5mm

Wilbers 642 custom (mine)

224

346

***WT is calculated. Length adjustable to: + 0/-10mm

^^^

Note: Sag %-ages use this number for the denominator in calculations below:

Price with discount was $899 + $100 for optional ride height (length) adjustment. No tax or shipping from beemershop.com.

Shock damping controls: Top (+) is Compression/low speed, below it (-) is Compression/high speed. At bottom of shock is Rebound.

-To close, turn clockwise. (For Rebound - this is viewed from underneath shock looking up).

-First close all the way (max damping), then open the desired # of clicks (range is 0-23 clicks).

Note: Seat height is to a point on the front edge, so relative only numbers.

-Factory setting is 12 clicks on each of Comp/Hi, Comp/Lo and Rebound.

Spring is marked 160-165 meaning: Spring rate=160 N/mm, and 165 uncompressed spring length.

-Preload factory setting is 9mm, the amount the spring is compressed (length = 156mm=165-9). In the pic you can see the gap between the 2 nuts and the top of the shock aluminum cone measures 10.8mm. (Later I would measure this shock length to be 157 so the preload is closer to 8.3mm in my measurements, which will calibrate to the preload settings I make later on, below).

Sag measurements (mm):

Length adjustable to: + 0/-10mm

Raw Measurements

Sag

Sag %-ages

^^^

A (Full Extension)

B (Unloaded, Vertical)

C (Loaded, Rider w/o gear (unless*))

A-B (Unloaded or Static Sag)

A-C (Loaded or Race Sag)

Unloaded % (A-B)/WT

Loaded % (A-C)/WT

Seat "Height" (Unloaded)

BMW Sachs (OEM)

7/12/10 - Before oil leak. With Gear On*

617.5

610

565

7.5

52.5

25%

8/24/10 - Now leaks oil at top, preload broken - knob spins freely and does not click. To top of swingarm). With Gear On*

572

544

493

13%

38%

857 (33.7in)

Wilbers 642

Note: All measurements on 8/24/10 - 7/21/11 or later have the yardstick placed on the top of swingarm near the rounded edge (see photo below) on right side. Then measure up to the bottom edge of the rearmost black metal mount tube of the BMW rear tail rack. Measurment in 2012 is similar.

Set to factory settings: 9mm preload on spring (length = 156mm=165-9). Length adj set to 0 (range is +0/-10mm). Very tall seat - tippy toes!

8/25/10: Rider: 196 lbs No gear on!

598

572

536

12%

28%

875 (34.4in)

590 on sidestand

8/25/10: Rider: 217lbs With Gear On*

598

572

530

12%

30%

8/26: I rode on Storm Mtn and experimented with Compression (Hi/Lo Speed) & Rebound. Factory set to 12/12 & 12, but it needs a LOT of rebound. Fully open (23/23 & 24) did not work and bottomed some. Also tried 0/0 & 0, a bit harsher but ok for jumps. Ended with 5/5 & 5. Maybe set C-Hi a bit more than C-Lo for off road, like 5/10 & 5?

Changed Length Adj set to -9mm (could not get it to -10mm) Better ride height for street!

8/30/10: Rider: 196 lbs No gear on!

567

541

505

12%

28%

856 (33.7in)

558 on sidestand

Tried again, seems like minimal sag, but same!

7/21/11: Rider: 194 lbs No gear on!

665

638

602

12%

28%

6/2012 Experiments with stiffer springs:

Side note: the full range of swingarm, with the shock removed and using tie-downs to lift it, I measured as a travel of 300mm… Now this was a crude measurement and probably does not match the BMW measurements, but note that the stock XChallenge air is 270mm travel & Ohlins BM636 is 305!

170 N/m spring:

Ted Porter at Beemershop installed a stiff spring is marked 170-165 meaning: Spring rate=170 N/mm, and 165 uncompressed spring length.

-Ted set preload to 8mm, (amount the spring is compressed (length = 157mm=165-8). I checked and to me it looks to be about 7.8mm. Spring length measures 6 3/16" or 157.2mm.

-I set the length adjuster to maybe -7mm or so, at 0 it was too tall really. I don't think it affects the sag. Neither did the compression and rebound clicks, I checked and no difference in sag.

6/19/12: Rider: 195 lbs No gear on! 7.8mm preload

558

529

489

13%

31%

Worse than before with 160Nm spring!

6/19/12: Rider: 233 = 195 lbs + 38 lb concrete block on pillion. 7.8mm preload

558

519

481

17%

34%

Worse than before with 160Nm spring!

Using the included Wilbers apanner wrench, I set preload to 10.6mm, (amount the spring is compressed (length = 165 - 154.4mm=10.6). Spring length measures 6 5/64" or 154.4mm. When you tighten the lower collar nut, it spins the entire lower part of the shock including the eye due to the binding pressure of the spring against the lower eye mount. You don't have to loosen the top collar locking nut. Do a full rotation to align the lower shock spacer offset on the same side. Every full turn of the collar nut will move one thread pitch which is right near 1/16" of an inch (or 1.58mm). I did 2 full turns or decreased the shock length (and increased the preload) it by around 3 mm. Now preload is about 10.6 mm.

6/20/12: Rider: 195 lbs No gear on! 10.6mm preload

569

548

507

28%

Hmmm worse than with 160Nm spring! Gap at top of spring nuts is now 13.1mm giving 10.6mm preload. Spring measured exactly 6 5/64" or 154.4 mm

180 N/m spring:

Ted Porter at Beemershop installed a stiff spring is marked 180-165 meaning: Spring rate=180 N/mm, and 165 uncompressed spring length.

-I reset preload to 9.0mm. Spring length measures 6 9/64" or 156.0mm.

7/7/12: Rider: 195 lbs No gear on! 9mm preload

603

579

543

11%

27%

I set preload: Gap at top of spring nuts is now 11.5mm giving 9mm of preload. Spring measured exactly 6 9/64" or 156.0 mm

7/7/12: Rider: 233 = 195 lbs + 38 lb concrete block on pillion. 9mm preload

603

566

530

17%

33%

Same setup, added block for weight.

YACUGAR Shock 3/2013 Sag measurements (mm):

Yacugar F-RS specs:

227

345

***WT is calculated. Length adjustable to: + 10/-0mm

Raw Measurements

Sag

Sag %-ages

^^^

A (Full Extension)

B (Unloaded, Vertical)

C (Loaded, Rider w/o gear (unless*))

A-B (Unloaded or Static Sag)

A-C (Loaded or Race Sag)

Unloaded % (A-B)/WT

Loaded % (A-C)/WT

Seat "Height" (Unloaded)

3/31/13 - Yacugar F-RS shock 23.14.120 with 66mm stroke and mount length 345mm +10 - 0, with 1101 progressive spring (180mm spring length, 147 - 227 N/mm dual spring rate). Mount length is 10mm longer than I asked for! Preload from factory was 5.4mm (180-174.6mm) as I measured it, but they said it was 4mm preload. Sag measured with shock at shortest length (345mm). And stroke that I used in these calculations is 66mm stroke, so 227mm wheel travel, (technically 1mm longer than Wilbers at 224mm travel).

Initial setup as shipped: Rider: 203 lbs No Gear On! *

672

631

587

18%

37%

Initial setup as shipped: Rider: 241 lbs = 203 + 38 lb concrete block on pillion.

672

617

573

24%

44%

4/8/13 - Increased Preload by 1.8 turns (=1.8 * 1.7mm = 3.1mm). So now is maybe 8.5mm (5.4 +3.1mm)?

Measured pitch of spanner nut: 3 turns to be 0.205" which is 1.7mm/turn (measured with calipers).

Preload=8.5mm Rider: 203 lbs No Gear On! *

672

640

595

14%

34%

4/12/13 - Increased Preload by 2.0 turns (=2 * 1.7mm = 3.4mm). So now is maybe 11.9mm (8.5 +3.4mm)?

Preload=11.9mm Rider: 203 lbs No Gear On! *

696

672

628

11%

30%

864 or 34.0"

Same except Rider: 241 lbs = 203 + 38 lb concrete block on pillion

696

660

617

16%

35%

4/17 Swapped old worn Mefo rear tire and wheel for new Dunlop D606 which is exactly 2" more in diameter

This raised seat height by 1.0" !!!

886 or 34.9"

Same preload except: Fully packed Great Basin bag (and small dry bag) is on pillion. Also tank bag but No rider gear or number plate bag. Ready for Utah trip.

703

666

629

16%

33%

875 or 34.45"

Ground Clearance (to oil drain plug) is 9.9"