Hydraulic Anti-Bottoming Systems - On Shocks?- Mtbr.com
Results 1 to 30 of 30
  1. #1
    Formerly PaintPeelinPbody
    Reputation: PHeller's Avatar
    Join Date
    Dec 2012
    Posts
    2,419

    Hydraulic Anti-Bottoming Systems - On Shocks?

    I've recently read a lot of good press about Push's ASC-3 fork coil conversion and one of the things people love is its hydraulic anti-bottoming system.

    I know many of proclaimed the same praises of Avalanche's ABS system as well.

    Then I noticed the Avalanche Montie (inline coil shock) has got ABS as well.

    If this is a good addition to high end coil forks, then does it have lots of value being on a coil rear shock as well?
    Work - Utility GIS Analyst
    Party - 2019 Guerrilla Gravity Revved Trail Pistol Sz 3

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jul 2009
    Posts
    1,166
    I think the EXT has it, as well.

  3. #3
    mtbr member
    Reputation: tbmaddux's Avatar
    Join Date
    May 2012
    Posts
    1,973
    Hydraulic anti-bottoming is in the Vorsprung Smashpot coil conversion, whereas the PUSH ACS-3 has a small air spring for anti-bottoming. And yes, for rear shocks you can find hydraulic bottom-out control on the EXT Storia and ARMA rear shocks.

  4. #4
    Formerly PaintPeelinPbody
    Reputation: PHeller's Avatar
    Join Date
    Dec 2012
    Posts
    2,419
    Ok, but what's the advantage? More usable travel? No worry of a spikey rebound when bouncing off the rubber bumpers?
    Work - Utility GIS Analyst
    Party - 2019 Guerrilla Gravity Revved Trail Pistol Sz 3

  5. #5
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Quote Originally Posted by PHeller View Post
    Ok, but what's the advantage? More usable travel? No worry of a spikey rebound when bouncing off the rubber bumpers?
    Coils are linear by nature so they rely on the frame's leverage ratio curve to "slow down". But sometimes that’s not enough so delivering a 50% increase in the force required to compress the shock during the last 15% of the travel is a good idea. (That’s what the EXT STORIA v3 does)

  6. #6
    mtbr member
    Reputation: minimusprime's Avatar
    Join Date
    May 2009
    Posts
    1,050
    A lot of time and engineering goes into bump stop specification and shape on coil over suspension systems. This is true for cars and motorcycles but also bicycles. Arguably, a properly specified bump stop is going to be a more simple to use and cheaper to implement setup then an HBO setup.

    Obviously, the folks at EXT know what they are doing, but so do the folks at push. From the position of needing to fit several frames and shock sizes, it's a safer bet to use a closed cell foam that's specified to add the progressiveness and bottom out resistance characteristics that you want.

    It is very inconvenient to utilize this sort of system in a fork, but very convenient to use this sort of system in a shock. This is why you will always see more physical bump stop bumpers then HBO systems in rear shocks.

    TLDR, don't under estimate the thought that goes into that little foam puck on your coil shocks. Also, take note that when you buy a DHX, you're getting one choice of bottom out bumper, which is another reason to go with something like the 11/6 over an off the shelf aftermarket shock.

    P.S. if learning more about bump stop materials and shapes is interesting to you... there is a ton of information in the motorsports world about this, specifically stock class autocross racing. Many times when you can't change the shocks bodies and springs out, the only mechanic you are left with is internal valving and bump stop bumpers. I spent a ton of my early motorsports career learning what length, shape and density worked best for the ride heights I was running on my stock class miata.

    example - Automotive Suspension Experts | Fat Cat Motorsports, Inc. | Bump stop application guide

  7. #7
    mtbr member
    Reputation: Dougal's Avatar
    Join Date
    Jan 2004
    Posts
    7,350
    Consider that virtually all air-shocks rely on a ~2.5mm thick rubber o-ring for a bottom-out stop. Coil shocks are running ~10-20mm thick foam bumpers.

    The vast majority of riders do not bottom their shocks out hard with the above bumpers.

    You don't want bottom-out control to engage too early or it destroys your mid-stroke response. But you also need a certain amount of stroke for it to fit and work.

    In a fork you have a lot of stroke to use, so having the last 20mm or so working in hydraulic bottom-out works quite nicely (20/160 = 12.5% of the stroke) and gives you lots of room to make it engage, then ramp up and go through several stages.

    In a shock with ~50-60mm of stroke you're down to 5-7mm. Trying to fit several stages of bleed off into 5-7mm is pretty ugly. Let alone trying to get a nice lead-in and progression into it.
    Owner of www.shockcraft.co.nz, Mech Engineer, Tuner, Manitou, Motorex, Vorsprung EPTC, SKF, Enduro
    www.dougal.co.nz

  8. #8
    mtbr member
    Reputation:
    Join Date
    Dec 2006
    Posts
    912
    Quote Originally Posted by minimusprime View Post
    A lot of time and engineering goes into bump stop specification and shape on coil over suspension systems. This is true for cars and motorcycles but also bicycles. Arguably, a properly specified bump stop is going to be a more simple to use and cheaper to implement setup then an HBO setup.

    Obviously, the folks at EXT know what they are doing, but so do the folks at push. From the position of needing to fit several frames and shock sizes, it's a safer bet to use a closed cell foam that's specified to add the progressiveness and bottom out resistance characteristics that you want.

    It is very inconvenient to utilize this sort of system in a fork, but very convenient to use this sort of system in a shock. This is why you will always see more physical bump stop bumpers then HBO systems in rear shocks.

    TLDR, don't under estimate the thought that goes into that little foam puck on your coil shocks. Also, take note that when you buy a DHX, you're getting one choice of bottom out bumper, which is another reason to go with something like the 11/6 over an off the shelf aftermarket shock.

    P.S. if learning more about bump stop materials and shapes is interesting to you... there is a ton of information in the motorsports world about this, specifically stock class autocross racing. Many times when you can't change the shocks bodies and springs out, the only mechanic you are left with is internal valving and bump stop bumpers. I spent a ton of my early motorsports career learning what length, shape and density worked best for the ride heights I was running on my stock class miata.

    example - Automotive Suspension Experts | Fat Cat Motorsports, Inc. | Bump stop application guide
    Is this actually Fat Cat or are you just using them for reference?

  9. #9
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    908
    Haven't encountered FCM before, some good videos on his youtube channel!
    www.thesuspensionlab.nz
    Servicing in Rotorua, NZ/Vorsprung Elite Tuning Centre/DVO service centre/Insta @thesuspensionlab

  10. #10
    Elitest thrill junkie
    Reputation: Jayem's Avatar
    Join Date
    Jul 2005
    Posts
    32,178
    Hydraulic ABS has saved my a$$ more than once when I landed on my front wheel or nearly lost control in a section, the fact that it dampens is significant IMO.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  11. #11
    mtbr member
    Reputation: minimusprime's Avatar
    Join Date
    May 2009
    Posts
    1,050
    Quote Originally Posted by Jesse Hill View Post
    Is this actually Fat Cat or are you just using them for reference?
    No, but I know Shaikh quite well. I was quite involved in the miata track racing and autoX scene for many years. I was sponsored and supported by Blackbird Fabworx and we utilized FCM suspension setups for a time... ultimately switching to Penske because we had some loftier goals.

    I grew up building and racing cars and motorcycles. I fancied myself quite good at setting up a car... that is, until I bought/built a miata. That was my car setup and building masters degree.

    There is no more true statement in life then, the more I learn, the more I learn I don't know. Suspension and aerodynamics are two areas that are humbling to say the least. Trying to adapt what I've learned on cars/motorcycles to bicycles is a mixed bag. The wheels fall off the bus when the majority of the mass is dynamic, and shaft speeds are a factor of 4-10x what a vehicle sees.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jul 2017
    Posts
    134
    Quote Originally Posted by minimusprime View Post
    Trying to adapt what I've learned on cars/motorcycles to bicycles is a mixed bag. The wheels fall off the bus when the majority of the mass is dynamic, and shaft speeds are a factor of 4-10x what a vehicle sees.
    Amen
    Seems like none of the knowledge I picked up from cars works on bikes.

    I will say though, the MTB community is way more open to talking about the specifics of damping behavior than the auto community. I don't think I've ever come across auto guys talking about how different pistons behave. Mostly just what your damping ratios should be and where the digressive knee should happen when it comes to specifics on dampers. I was never in the Miata stuff though so maybe they did. I'll give them credit though, they did more with 130hp then I could with 400. lol.

  13. #13
    mtbr member
    Reputation:
    Join Date
    Dec 2007
    Posts
    6,661
    I had the same question as the OP.

    Thanks Dougal for making sense of it.

    Quote Originally Posted by Dougal View Post
    Consider that virtually all air-shocks rely on a ~2.5mm thick rubber o-ring for a bottom-out stop. Coil shocks are running ~10-20mm thick foam bumpers.

    The vast majority of riders do not bottom their shocks out hard with the above bumpers.

    You don't want bottom-out control to engage too early or it destroys your mid-stroke response. But you also need a certain amount of stroke for it to fit and work.

    In a fork you have a lot of stroke to use, so having the last 20mm or so working in hydraulic bottom-out works quite nicely (20/160 = 12.5% of the stroke) and gives you lots of room to make it engage, then ramp up and go through several stages.

    In a shock with ~50-60mm of stroke you're down to 5-7mm. Trying to fit several stages of bleed off into 5-7mm is pretty ugly. Let alone trying to get a nice lead-in and progression into it.
    Guerilla Gravity Shred Dogg
    Fezzari Signal Peak (For Sale)
    Pivot Shuttle (wife's)

  14. #14
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723

    Hydraulic Anti-Bottoming Systems - On Shocks?

    Just a thought. Can changing the bottom out bumper make the shock feel more «bottomless»?!





    When I bottom out my CCIL Coil I can definitely feel it.

    FYI: http://www.avalanchedownhillracing.c...r%20Bumper.htm

  15. #15
    mtbr member
    Reputation:
    Join Date
    Oct 2018
    Posts
    141
    Quote Originally Posted by digev View Post
    Just a thought. Can changing the bottom out bumper make the shock feel more «bottomless»?!
    Yes they can, but something like shape factor bumper cannot be safely used on shocks with very thin shafts like DHX2 or CC stuff because it could actually snap it.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Quote Originally Posted by ghostbiker View Post
    Yes they can, but something like shape factor bumper cannot be safely used on shocks with very thin shafts like DHX2 or CC stuff because it could actually snap it.
    Oh Ok. So an 8mm shaft is too thin?

    Thanks for replying

  17. #17
    mtbr member
    Reputation:
    Join Date
    Oct 2018
    Posts
    141
    Quote Originally Posted by digev View Post
    Oh Ok. So an 8mm shaft is too thin?

    Thanks for replying
    If 9mm one on dhx is I would say so, unless DHX is alu and CC is steel, but I don´t think that is the case.

  18. #18
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,263
    Well I've got a 8mm solid steel shaft on my db coil. It's bottoms like a & *-*4. I'm 95 kg....

    Is there any aftermarket bumper solution?

  19. #19
    mtbr member
    Reputation: minimusprime's Avatar
    Join Date
    May 2009
    Posts
    1,050
    Quote Originally Posted by ghostbiker View Post
    Yes they can, but something like shape factor bumper cannot be safely used on shocks with very thin shafts like DHX2 or CC stuff because it could actually snap it.
    source?

  20. #20
    mtbr member
    Reputation:
    Join Date
    Oct 2018
    Posts
    141
    Quote Originally Posted by minimusprime View Post
    source?
    Avalanche

  21. #21
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Quote Originally Posted by CaveGiant View Post
    Well I've got a 8mm solid steel shaft on my db coil. It's bottoms like a & *-*4. I'm 95 kg....

    Is there any aftermarket bumper solution?
    I've only found Avalanche. It might be worth sending them an email to ask about the 8mm shaft compatibility! I'd be interested too because the CCIL bumper is too "flat" in my opinion.

  22. #22
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Shaft diameter is one thing but the bumper diameter should be taken into account as well, no?

    .750 or .875 for $16.95 on the following page

    http://www.avalanchedownhillracing.com/service.html

    We still don’t know the shaft diameter compatibility.

  23. #23
    mtbr member
    Reputation: Dougal's Avatar
    Join Date
    Jan 2004
    Posts
    7,350
    Quote Originally Posted by digev View Post
    Just a thought. Can changing the bottom out bumper make the shock feel more «bottomless»?!
    Yes.
    Owner of www.shockcraft.co.nz, Mech Engineer, Tuner, Manitou, Motorex, Vorsprung EPTC, SKF, Enduro
    www.dougal.co.nz

  24. #24
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    908
    Quote Originally Posted by digev View Post
    Shaft diameter is one thing but the bumper diameter should be taken into account as well, no?

    .750 or .875 for $16.95 on the following page

    Avalanche service

    We still don’t know the shaft diameter compatibility.
    yes, lower "spring rate" but longer is what you are aiming for so its effect is more gradual. 2 bumpers of the same material but different OD will have a different Rate
    www.thesuspensionlab.nz
    Servicing in Rotorua, NZ/Vorsprung Elite Tuning Centre/DVO service centre/Insta @thesuspensionlab

  25. #25
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Yeahhh! That’s what I wanted to hear thank you guys! Do you sell some for the CC shocks please or are they part of an overall tuning service?

  26. #26
    mtbr member
    Reputation:
    Join Date
    Oct 2018
    Posts
    141
    ohlins bumper could be possibly the best option, I cannot find what shaft size they use though.

  27. #27
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    Got an answer from Avalanche about the 8mm CC shaft.

    Code:
     Sorry we do not make or sell bumpers this small.

  28. #28
    mtbr member
    Reputation:
    Join Date
    Jun 2006
    Posts
    908
    Quote Originally Posted by ghostbiker View Post
    ohlins bumper could be possibly the best option, I cannot find what shaft size they use though.
    Ohlins is an 8mm shaft like cane creek
    www.thesuspensionlab.nz
    Servicing in Rotorua, NZ/Vorsprung Elite Tuning Centre/DVO service centre/Insta @thesuspensionlab

  29. #29
    mtbr member
    Reputation:
    Join Date
    Oct 2018
    Posts
    141
    Quote Originally Posted by JohnnyC7 View Post
    Ohlins is an 8mm shaft like cane creek
    Well then, if you can source one and need it...I don´t think there is anything more suitable for CC really.

  30. #30
    mtbr member
    Reputation:
    Join Date
    Mar 2019
    Posts
    723
    That cool guys thank you very much! Let’s see what I find.

Similar Threads

  1. Bicycle anti-theft systems (gps tracker)
    By IxIRenegadeIxI in forum General Discussion
    Replies: 3
    Last Post: 01-08-2014, 09:59 AM
  2. Rock Shocks Recon 351 bottoming out giving me only 1 inch travel
    By nice_camel_toe in forum Shocks and Suspension
    Replies: 51
    Last Post: 09-29-2013, 02:28 PM
  3. Suspension Systems vs. Other Suspension Systems
    By skier_biker_baller in forum All Mountain
    Replies: 13
    Last Post: 05-25-2012, 11:49 PM
  4. Semi-OT : Anti-Theft systems
    By Cloxxki in forum 29er Bikes
    Replies: 3
    Last Post: 08-21-2005, 01:55 PM
  5. 05' Stumpy FSR Disc 120 Hydraulic brake systems
    By Ol' DirtDawg in forum Specialized
    Replies: 9
    Last Post: 06-02-2005, 09:26 AM

Members who have read this thread: 134

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.