Rear shock - Options Fastace or Yasusu

[Animalector]

I was hoping someone could share their experience with with the following rear shocks. I've currently got a 270mm eye-to-eye on my greyborg and it's "maybe" a bit long. The riding position isn't bad with plenty of ground clearance. I could do 260mm, but would not want to go shorter.

Yasusu BK7 http://www.yasusu.com/pro_bic01.htm

Fastace BS22-AR http://www.dhz.com.au/buy/fastace-rear-shock-model-bs-22ar-270l/SUS-01

They both end up at about $100USD delivered.

Does anyone have opinions or wish to comment on these shocks. I note that the Yasusu has compression and rebound damping adjustment.

Does anyone care to comment on 260mm vs 270mm??

It is for a greyborg, with pit bike front suspension, and plenty of weight (plus a 100kg rider)

Thanks
Andy

 

[full-throttle]

No experience with either, but

BK7 has compression adjustment and a piggy back, def a plus

Stroke on 260 will be less than on 270, so less travel

 

[Animalector]

Thanks for that,

I've often wondered how much difference a piggy back makes and why? just because of the increased volume perhaps?

might have to contact yasusu to ask about their stroke length, 60mm at 3.7 leverage ratio (I think for the borg) would be 222mm which is plenty.

Later
Andy

 

[full-throttle]

Piggy back allows easier control of compression stroke, greater oil volume and often longer stroke (no space taken by IFP)

 

[zombiess]

I currently have 3 different rear shocks: 2 Fast Ace rear shocks, a 240mm with adjustable compression/rebound, 600lb spring, a 280mm adjustable rebound with 550lb spring and a DNM Burner RCP2, adjustable rebound, compression 650lb spring.

I have only run the Fast Ace Force RC I purchased for around $50 shipped new off ebay. I then had to pay someone in Poland (Pro Shox) to custom manufacture the bushes for me $110 for both Fastace shocks.

I should be swapping out to the DNM shock this weekend. I don't feel the compression setting making much of a difference on the Fastace shock (a working decent shock for $50 is a win for sure), but the rebound adjustment works great. The 600lb spring is OK for my 175lb weight, but is probably too soft for a heavier rider or off road use. It is very cushy on the street. I upped the pre load to help reduce pedal strikes on suspension compression by reducing sag a little, I have my suspension set very soft because I ride street and like it to feel like a couch. I believe the DNM shock will be a better match. I had 4 of them made to spec (all the bushes are the correct width to fit the frame/swing arm) to fit these frames since a single unit shipped was over $250 after all the dang fees were included.

As for length I am 6'1 (183cm tall) and only around 3-4CM of my seat post is visible above the tube. The 240mm length is perfect for me with 19" motor cycle wheels with a 25.3" diameter. If I installed my longer shock it would be a bit more difficult to mount the bike and I would have to set more sag, but this is one of those things that is a personal choice. Since not many have built and ridden these bikes I try to post up what ever info I have discovered since I'm one of the first on this new design. Getting a working shock setup was the hardest to figure out for me.

I let a stranger ride my Greyborg yesterday who had dirt bike and street bike experience and he loved it. One of the first things the guys who stopped me commented on was the bike looked like it has huge suspension travel (it does).

 

[made_in_the_alps_legacy]

Piggy back allows easier control of compression stroke, greater oil volume and often longer stroke (no space taken by IFP)

they sometimes also act as "end of compression" control (with an adjustable spring loaded valve aimed to allow the user to decide at with compression this volume would add up to the main piston volume)

 

[full-throttle]

It's called the Boost valve
Either designs can and do incorporate it

 

[Animalector]

well no email response from Yasusu, so looks like Fastace is really the only option for a $100 rear shock

Anyone suggest an alternative?

Andy

 

[zombiess]

well no email response from Yasusu, so looks like Fastace is really the only option for a $100 rear shock

Anyone suggest an alternative?

Andy

DNM, shipping might be cheaper to you since you are closer to them.

 

[Animalector]

actually I heard from Yasusu this afternoon so they're back in the "options list"

Andy

 

[GiantEV]

Which shock did you end up going with?

 

[Animalector]

I was cheap and bought a local DNM basic Downhill shock, then had to build a mount to extend it's length. only simple rebound damping adjustment but it worked well..

Goodluck.

Andy

 

[Offroader]

I haven't researched but I would figure the greyborg was designed around downhill shocks?

I looked into motorcycle shocks for my raptor and none would fit right. The problem was that most motorcycle shocks don't have the right amount of travel (stroke) for the size of the shock length (eye to eye). Most of the strokes of the motorcycle shocks are too small and to get the right size you need a very long shock length which won't fit.

I think you could find a compatible shock but it is difficult and needs to be special ordered.

Personally I would think a motorcycle shock would deal with the heavy hub motor better than a downhill shock as motorcycles have much heavier rear wheels than downhill bikes. It would deal with the rebound better also.