Air Shock Stroke Adjustments Via Bumpers - What Changes?- Mtbr.com
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  1. #1
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    Air Shock Stroke Adjustments Via Bumpers - What Changes?

    I'm doing research into what's going inside the current Rockshox Deluxe lineup in terms of stroke adjustment.

    For example, you can get a Deluxe in 230x63, 230x60, and 230x57.5.

    I was curious: what's different inside these shocks that limits (or extends) the stroke? Looking at SRAM's spare parts manuals, the 230mm i2i shock uses the same air can for various stroke lengths, and there is no indication that any "hard part" changes either. Now, one thing I did notice is that in that spare parts manual it does give a different part number for "Damper Body/IFP" for various stroke lengths on the MONARCH, but the Deluxe is missing this.

    However, the new Trek-specific through shaft (which utilizes a 230x57.5 stroke shock) has a diagram with an interesting bit added...some sort of washer/bushing thing between the bottom out bumper and the space where the volume spacers sit (and the damper body threads into).

    Air Shock Stroke Adjustments Via Bumpers - What Changes?-rs-super-deluxe-spare-parts-stroke-limiter.jpg

    Anyway, what clued me in to the fact these shocks (2017+ Deluxe/Super Deluxe) are stroke limited by "soft parts" are these pictures at the red round washer from NSMB.com:

    Air Shock Stroke Adjustments Via Bumpers - What Changes?-rs-super-deluxe-nsmb-stroke-limiter.jpg
    Air Shock Stroke Adjustments Via Bumpers - What Changes?-rs-super-deluxe-nsmb-stroke-limiter2.jpg

    That red round thing is clearly NOT a volume spacer (although it might act like one).

    One hard part that might be different are the washers on both ends of this bumper. Those washers sit on the lip of the shock body/damper threading, and stroke limited shocks (60mm and 57.5mm) must have washers on both sides of the bumper (as shown in the parts diagram above).

    This pic shows two "stacked" washers in grey:
    Air Shock Stroke Adjustments Via Bumpers - What Changes?-imc2235.jpg
    This looks like just a single washer:


    Here it looks like Trek was using a blue washer of some sort:
    Air Shock Stroke Adjustments Via Bumpers - What Changes?-rs-super-deluxe-spare-parts-stroke-limiter2.jpg

    Here you can see that an unlimited shock only has a single washer:

    Air Shock Stroke Adjustments Via Bumpers - What Changes?-rockshoxdeluxecutaway.jpg

    ...and this isn't a new thing either. Way back when, Push was using what amounted to a coil shock bump stop in the old Fox Vanilla!

    477977d1250875975-my-push-bottom-out-bumper-disintergrating-flaot.jpg


    So, my question is: what else is happening inside a stroke limited shock vs an unlimited shock? Different IFP pressure? Different tunes? Is there anything stopping me from inserting a larger stroke limiter (the round red thing) to make my shock a 230x55? Or 230x50?
    Last edited by PHeller; 06-12-2018 at 09:40 AM.
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  2. #2
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    I have been wondering the same thing. I have an Anthem with a 165x42.5 and would love to squeeze all the travel I can out of it. I know they make and a 165x45 and it seems to me that the only difference would be a reducer somewhere and a different ifp stancion with gradient markers for 42.5. I plan to tear into it and do a full service in the next month and see what I can do to get it to 45.

  3. #3
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    Unless your frame is very liner (uncommon these days), some weird stuff can happen past the factory stroke. With only 7mm more stroke, my old reign developed a very strange pause at bottom out. It would extend past stock and pause there before rebounding. It felt like packing down, but times ten. The leverage ratio went insane that far in.

  4. #4
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    Yea I'm not so interested in exceeding the stock stroke as I am limiting the shock to match the front travel or achieve better tire clearance, so taking a 150mm frame and limiting it to 130mm or something.

    As far as the Reign and other Mini-Link/VP/DW bikes, it wouldn't surprise me if things got wonky past the intended stock travel. I think some designs handle increases in travel better than others.
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  5. #5
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    Have you guys found anything interesting regarding lengthening of deluxe stroke?

  6. #6
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    Theres nothing to it; you simply pull out the stroke limit spacer/bumper if it has one. There are three stanchion bodies produced: 45, 55 and 65mm.

    Howevee, pulling the stroke limiter could result in tire contact on bottom out or other bad things, so its a bit more risky than limiting the stroke. For example some frames run a 230x57 shock, pull the 8mm spacer on those shocks could gain you 20mm of travel or more...but that also will likely send your tire into your seat tube.

  7. #7
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    Considering my shock is trunnion mount RS deluxe with 185x52.5 it should have 2.5mm spacer with 55mm stroke stanchion body?, correct?


    My bike, giant trance, has stock 185x52.5, but giant actually sels aftermafket shock for the same frame with 185x55, that should change rear wheel travel from 140mm to 147mm-ish.

    great news, tnx

  8. #8
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    Bump.

    Still curious if anyone knows if there are differences between the 230x63 and 230x57.5 shocks outside of this red stroke bumper?
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  9. #9
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    Quote Originally Posted by PHeller View Post
    Bump.

    Still curious if anyone knows if there are differences between the 230x63 and 230x57.5 shocks outside of this red stroke bumper?
    No differences, ifp depth and pressure are the same for all strokes, and damper tunes will be selected based on the leverage ratio of the frame. In theory the longer stroke shocks will usually have a softer tune but that isnít guaranteed

  10. #10
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    Quote Originally Posted by JohnnyC7 View Post
    ...damper tunes will be selected based on the leverage ratio of the frame. In theory the longer stroke shocks will usually have a softer tune but that isnít guaranteed
    Can you elaborate a little more on that?

    Say, what the real world differences might if you take a 230x65mm shock tuned for a big travel bike, and then run it on a shorter travel bike at 230x57.5?

    Since you seem to know a bit about the subject, can you think of how "stroke limiting" a 230x65 shock down to say...230x50 or 45...or 40 might impact performance or reliability of the shock?
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  11. #11
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    They only intend them to be reduced by 5mm, if you reduced it more than that the volume of the air can wonít have reduced enough to give decent progression, even with volume reducers added. So the bike would blow through its travel and bottom out frequently even with high pressure in the air can. So 65 to 50mm wouldnít be a good idea and I canít think of a bike where that would fit anyway

  12. #12
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    Quote Originally Posted by JohnnyC7 View Post
    They only intend them to be reduced by 5mm...
    Except there are plenty of 230x57.5 shocks floating around, which are 7.5mm reduction in stroke.

    What you're getting at though is that you need to remove volume along with stroke. That might be why the stroke bumpers of the Super Deluxe are pretty big, they effectively reduce the volume of the air can as well.

    Also I'm not sure what you mean by "fit". Plenty of bikes run 230mm i2i shocks. Stroke limiting them from say...160mm travel down to 140mm wouldn't require any change in "fitment".
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  13. #13
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    Quote Originally Posted by PHeller View Post
    Theres nothing to it; you simply pull out the stroke limit spacer/bumper if it has one. There are three stanchion bodies produced: 45, 55 and 65mm.
    I wanna do the opposite, reduce a 210x55 to 210x50. Can't find anything on the RS parts manuals that show what you'd need to buy/source to make it happen.
    I like 'em long, low, slack and playful

  14. #14
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    I would think you would just need this 5mm spacer and an additional steel washer. My spacer was sandwiched between 2 washers but if yours didnít come with a travel spacer you may have only one washer.
    I cut mine out of a Super Deluxe 230x60 to make it 65mm stroke and 170mm travel on a YT Capra 29.


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  15. #15
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    Yep. You don't even really need the washers I don't think. I think you could cut a notch just wide enough to squeeze the spacers onto the shaft and you'd be golden.
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  16. #16
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    Sesostris, would you be able to post up the ID and OD dimensions of the spacer you cut out of your SuperDeluxe?
    I like 'em long, low, slack and playful

  17. #17
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    2018 Deluxe
    Shock stroke. Ifp insertion depth
    57,5mm. 67,2mm
    60mm. 69,3mm
    62,5mm. 71,4mm
    65mm. 73,5mm

    I'm not an expert but It seems like you have to do something more than cut the blue-plastic washer...
    I have the 2018 Deluxe rt 230x60 and i Will like to increase to 65mm but not sure how to do It well yet...

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    What would happen, if you would not change the depth of IPF? What would be the effect on the damping?

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    The IFP on an inline shock could contact the main piston before the shock reaches its true bottom out.

  20. #20
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    Quote Originally Posted by Sesostris View Post
    I would think you would just need this 5mm spacer and an additional steel washer. My spacer was sandwiched between 2 washers but if yours didnít come with a travel spacer you may have only one washer.
    I cut mine out of a Super Deluxe 230x60 to make it 65mm stroke and 170mm travel on a YT Capra 29.


    Sent from my iPhone using Tapatalk
    Did the two remaining washers rattle in the shock after removing this travel reducing spacer?

  21. #21
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    Hello everyone. I Just registert to this forum to give you my experience. I changed the stroke from 60mm to 65mm of my RockShox Deluxe RT. What you have to do to Change stroke is: remove the plastik spacer AND increase the ifp Volume. I did a Test Without increasing the ifp volume and as expected the piston touches the ifp and the stroke is still 60mm and at heavy bottomouts the ifp will damage i thing. So i disassembled the ifp (the original RockShox manual is super good) and increased the ifp Volume. After that i did a test and the stroke is 65mm now, as expected. I hope it helps some people doing the same. And it does not rattle inside (there ist a O Ring after the two washers). My Bike is a yt jeffsy 27 Al one, so the rearsuspension kinematic can handle the more stroke Without any problems. By the side, i also Upgraded my fork, But thats easier as the rearshock i thing. I habe a RockShox Pike RC and Upgraded from 150mm soloair to 160mm debonair (using a new upgrade airshaft).
    Last edited by Freeridernbg; 01-31-2019 at 10:56 AM. Reason: More Infos

  22. #22
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    ^^^great info

    Increased IFP volume by how much?
    I like 'em long, low, slack and playful

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    Quote Originally Posted by 06HokieMTB View Post
    ^^^great info

    Increased IFP volume by how much?
    @nusckas already gave the answer. It is described RockShox service manual how deep the ifp cap should be (an so how much damping oil there will be).

  24. #24
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    Confused...


    I want to shorten the stroke. 200x51 to 200x45.

    I am reading two things? Throw a bottom out gnar dog in it or move some washer thing?

    Any more detail would be appreciated.

    Iíve been inside and rebuilt the whole shock. That seems pretty straightforward just donít understand the difference between the gnar dog and the washers.

    TIA

  25. #25
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    Gnar dog is only to reduce volume. It will not shorten the stroke l, but it will make last few millimeters of it harder to reach.

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    Quote Originally Posted by elephant View Post
    Confused...


    I want to shorten the stroke. 200x51 to 200x45.

    I am reading two things? Throw a bottom out gnar dog in it or move some washer thing?

    Any more detail would be appreciated.

    Iíve been inside and rebuilt the whole shock. That seems pretty straightforward just donít understand the difference between the gnar dog and the washers.

    TIA
    You need to reduce the stroke. A air volume spacer does not reduce the stroke.

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    I think Iíve got it sorted. I am going to add a delrin spacer on the Ďstroke-sideí of the bottom out washer and add a second washer- spacer between two washers.

    I will report back.

  28. #28
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    To be clear you can shorten the stroke by adding too many volume spacers, ie making a bigger bottom out bumper. Obviously this impacts tuning far more than the stroke reducing washers.

    It might be possible to make cut down 4 volume reducers to limit stroke without having significant impact on volume.
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  29. #29
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    Bump.

    I have a 230 x 60 Deluxe. Would like to extend it to 65mm. What do I need to remove?

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    Quote Originally Posted by Freeridernbg View Post
    Hello everyone. I Just registert to this forum to give you my experience. I changed the stroke from 60mm to 65mm of my RockShox Deluxe RT. What you have to do to Change stroke is: remove the plastik spacer AND increase the ifp Volume. I did a Test Without increasing the ifp volume and as expected the piston touches the ifp and the stroke is still 60mm and at heavy bottomouts the ifp will damage i thing. So i disassembled the ifp (the original RockShox manual is super good) and increased the ifp Volume. After that i did a test and the stroke is 65mm now, as expected. I hope it helps some people doing the same. And it does not rattle inside (there ist a O Ring after the two washers). My Bike is a yt jeffsy 27 Al one, so the rearsuspension kinematic can handle the more stroke Without any problems. By the side, i also Upgraded my fork, But thats easier as the rearshock i thing. I habe a RockShox Pike RC and Upgraded from 150mm soloair to 160mm debonair (using a new upgrade airshaft).
    I would like to do this but am wary to do so with my only experience being adding / removing spacers to a RS deluxe RT shock (2018). Still might give it a go if the manual does a good enough job at describing the process of disassembling the IFP step by step. Thanks for the info!

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    LBS is willing to do it for Ä150, which is more than I can cough up atm. Do you think the process is easy enough for a regular dude with marginal experience with bike maintenance?
    Also: did you buy the IFP measurement tool to adjust the IFP to exactly 73,5mm?

  32. #32
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    Some great insights here guys. I've been wondering, I'm looking for a 210 mm shock and there seems to be way more 216mm around. Is there any way one could add a spacer on the negative spring side so shorten the eye to eye by 6mm? I only need a 55mm stroke and if I remove all travel limiting spaces this should still be achievable. I guess the answer is going to have something to do with the negative spring equalizing dent? Over to you.

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    Video needed

    Is there a video out there showing the process? I would love to to this on my YT.

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    I've got a RS Super Deluxe, I want to extend from 60mm to 65mm.

    This may be a dumb question. Can I just cut the 5mm spacer out? I don't need to do anything with the IFP, that's only for RS Deluxe correct?

  35. #35
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    Quote Originally Posted by breezy23 View Post
    I've got a RS Super Deluxe, I want to extend from 60mm to 65mm.

    This may be a dumb question. Can I just cut the 5mm spacer out? I don't need to do anything with the IFP, that's only for RS Deluxe correct?

    I cut mine out.

  36. #36
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    Quote Originally Posted by mikesee View Post
    I cut mine out.
    Yup, that worked. Confirmed IFP depth for super deluxe was the same for a whole bunch of stroke lengths. Pretty straight forward and added a couple tokens to take a little more to bottom out.

  37. #37
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    How we all doing?

    I think I'm finally ready to tear apart my cheapo Deluxe RT to remove the travel spacer and open her up to 55mm. Sounds like I shouldn't have any issues with the IFP depth.
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  38. #38
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    Anyone know where I can purchase these travel spacers?
    I'm looking to downsize a 60/65 stroke shock to 57,5. But I'm unable go source those travel spacers. Any hints for me?
    Thanks in advance!

  39. #39
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    Call the manufacturer or a tune shop.

    I doubt any retailers are carrying them.
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