I’ve used the Runt before on a different fork. While it will work on the Zeb, it won’t negate volume like a TruTune it will just...
I’ve used the Runt before on a different fork. While it will work on the Zeb, it won’t negate volume like a TruTune it will just give you an air pressure for ramp. The graph I posted was stock with 0 volume spacers. So for me, I’m not looking for ramp up, I’m trying to reduce it for a more linear feel.
I just got my Vorsprung Secus. So I can install that and ride this weekend.
@carlinojoevideo How did the TrueTune and Secus work together by the way?
I’ve used the Runt before on a different fork. While it will work on the Zeb, it won’t negate volume like a TruTune it will just...
I’ve used the Runt before on a different fork. While it will work on the Zeb, it won’t negate volume like a TruTune it will just give you an air pressure for ramp. The graph I posted was stock with 0 volume spacers. So for me, I’m not looking for ramp up, I’m trying to reduce it for a more linear feel.
I just got my Vorsprung Secus. So I can install that and ride this weekend.
Those are very old news, I'm almost sure that he came up with that just before fox released 38, must have been pretty pissed they used the same design. All things considered it's pretty reasonably priced too.
Those are very old news, I'm almost sure that he came up with that just before fox released 38, must have been pretty pissed they used...
Those are very old news, I'm almost sure that he came up with that just before fox released 38, must have been pretty pissed they used the same design. All things considered it's pretty reasonably priced too.
The 38 uses the space between the inner tube and the stanchion to increase the lower leg volume. This also allowed to move lower the seal head, slightly increasing the neg.volume.
The Luft Fusion linked above used all the space between the inner tube and the stanchion to double the neg.volume. The trade off was that by using a smaller piston than stock the pressure requirements could exceed the maximum limit set by factory.
Both system also slightly increased positive volume. The inner cylinder is shorter than the stanchion: so the upper part of the pos.chamber has a larger diameter.
The new upcoming Luft Fusion uses a much simpler design that allows lower pressures (+25 / 35%) keeping the same performances. In addition, bottom-out resistance caused by air in the lower legs is reduced by 8-10 kg.
The old zeb is already quite progressive in long travel, the 2023 much more because the luftkappe style piston steals pos.volume to increase the neg. Plus the buttercups takes space in the lower leg.
The effect of lower leg volume is not shown in the charts.
I had a secus in my A1 zeb ultimate and now a smashpot. Always ran it at 170mm. The secus was a fantastic upgrade to the zeb over the standard A1/B1 air spring and the smashpot was once again, a great upgrade over the secus. I can't say which one I preferred more as both were very good... In the end, I'd say the choice comes down to if you want to be weight concious and if you prefer the rebound feel or air vs coil. I don't think i was giving up anything in terms of performance between the two, just comes down to feel. Although, I will say that braking bumps with the smashpot are a non-issue... that part of it is sublime.
Regarding the smashpot... It's a great system overall, install is fiddly and there are a few things I can pass along from installing a few of them.
1) Heat the crap out of the heat shrink that goes on the inner shaft as it has a propensity to migrate down and cover the HBO holes (item 2.5 in the install instructions). There is some nuance to how you trim it on the top (where the upper travel shaft slots into the bottom), don't be afraid to having it tight, just about up against the outer shaft so that it clamps down and won't migrate. I would also cut the bottom of it a bit further away from the HBO supply holes then the instructions show as the lubrication can/will cause the heat shrink to migrate and loosen up slightly. The function this shrink wrap serves is noise reduction, and I haven't seen an increase in noise for cutting it back 1cm further away then the instructions show. If you're having an issue where you can't use the last 30mm of travel, this shrink wrap is most certainly migrated.
2) I'd go ahead and re-shim the HBO right off the bat, prior to the first install. They ship with 5 shims that you can re-sequence in the stack and move up above the clamp shim to get more/less hbo impact. (page 22 of the instructions) I would start by moving 2-3 of the shims above the clamp, leaving two in place up against the bottom out cone. I would also recommend using a 5wt oil to start with in lieu of the 20wt they suggest. I shred pretty decently for a 42 yr old, 180lb dude... and even with only running 2 hbo shims and 5wt oil, I do not have the HBO adjuster cranked down. I did elect to run a 50lb spring in lieu of the 45lb spring they suggested, which turned out to be the right choice... but still, I can't see where a situation in which running a spring below, would require that i run all 5 shims and/or 20wt oil. For reference, a buddy of mine that i ride with is running one of these as well, he's 6'7" - 270lbs and rides well... I still ended up swapping shims around for him leaving 3 in place and he is also running 5wt oil. Without doing that, the hbo engages pretty harshly and ramps up hard... If you are absolutely sending it to the level that the top 2-4% of riders at the whistler bike park are, maybe you'd need more hbo ramp... but I still doubt it.
3) Check the spring pre-load, check it again. Ride the fork for 4-5 rides, and check it once more. I found that it was changing as the spring broke in. I'm still talking to vorsprung about this as I had to do this twice since install and that's not necessarily how spring steel should work. I think I may need a new spring... but if your smashpot is making noise or topping out, I'd absolutely assume it's the spring pre-load that's causing it. Oddly, not enough pre-load seems to make a similar clunk/thud near topout that having too much seems to. You can check the pre-load without completely removing the unit, but you need to follow the procedure for the spring swap... otherwise the shaft will drop into teh abyss and you'll need to remove it anyway.
Regarding the lowers connection mod, I was thinking... Does it really do anything? Sure, it lowers the pressure build up in the spring side lower, but will increase it on the damper side. So is this a situation of lowering the spring side lowers force and increasing it on the damper side, effectively moving some apples from one pile to the other one?
Regarding the lowers connection mod, I was thinking... Does it really do anything? Sure, it lowers the pressure build up in the spring side lower, but...
Regarding the lowers connection mod, I was thinking... Does it really do anything? Sure, it lowers the pressure build up in the spring side lower, but will increase it on the damper side. So is this a situation of lowering the spring side lowers force and increasing it on the damper side, effectively moving some apples from one pile to the other one?
Because of the large difference in sealed volume between the sides, I assume it makes the overall force generated by lower leg ramp...lower.
The seal head on the spring side effectively seals the entire stanchion, the damper side has tons more volume in comparison. The majority of casting ramp is generated from the spring side, that's what you feel. If one side is 6spi at bottom, and the other 2psi, what you are feeling is the 6psi. If you connect them and now they are both 3psi at bottom, that is a big improvement.
But the total volume stays the same and the surface area the pressure applies to also stays the same. That's why I'm wondering if the total force across both sides might actually stay the same...
I had a secus in my A1 zeb ultimate and now a smashpot. Always ran it at 170mm. The secus was a fantastic upgrade to the...
I had a secus in my A1 zeb ultimate and now a smashpot. Always ran it at 170mm. The secus was a fantastic upgrade to the zeb over the standard A1/B1 air spring and the smashpot was once again, a great upgrade over the secus. I can't say which one I preferred more as both were very good... In the end, I'd say the choice comes down to if you want to be weight concious and if you prefer the rebound feel or air vs coil. I don't think i was giving up anything in terms of performance between the two, just comes down to feel. Although, I will say that braking bumps with the smashpot are a non-issue... that part of it is sublime.
Regarding the smashpot... It's a great system overall, install is fiddly and there are a few things I can pass along from installing a few of them.
1) Heat the crap out of the heat shrink that goes on the inner shaft as it has a propensity to migrate down and cover the HBO holes (item 2.5 in the install instructions). There is some nuance to how you trim it on the top (where the upper travel shaft slots into the bottom), don't be afraid to having it tight, just about up against the outer shaft so that it clamps down and won't migrate. I would also cut the bottom of it a bit further away from the HBO supply holes then the instructions show as the lubrication can/will cause the heat shrink to migrate and loosen up slightly. The function this shrink wrap serves is noise reduction, and I haven't seen an increase in noise for cutting it back 1cm further away then the instructions show. If you're having an issue where you can't use the last 30mm of travel, this shrink wrap is most certainly migrated.
2) I'd go ahead and re-shim the HBO right off the bat, prior to the first install. They ship with 5 shims that you can re-sequence in the stack and move up above the clamp shim to get more/less hbo impact. (page 22 of the instructions) I would start by moving 2-3 of the shims above the clamp, leaving two in place up against the bottom out cone. I would also recommend using a 5wt oil to start with in lieu of the 20wt they suggest. I shred pretty decently for a 42 yr old, 180lb dude... and even with only running 2 hbo shims and 5wt oil, I do not have the HBO adjuster cranked down. I did elect to run a 50lb spring in lieu of the 45lb spring they suggested, which turned out to be the right choice... but still, I can't see where a situation in which running a spring below, would require that i run all 5 shims and/or 20wt oil. For reference, a buddy of mine that i ride with is running one of these as well, he's 6'7" - 270lbs and rides well... I still ended up swapping shims around for him leaving 3 in place and he is also running 5wt oil. Without doing that, the hbo engages pretty harshly and ramps up hard... If you are absolutely sending it to the level that the top 2-4% of riders at the whistler bike park are, maybe you'd need more hbo ramp... but I still doubt it.
3) Check the spring pre-load, check it again. Ride the fork for 4-5 rides, and check it once more. I found that it was changing as the spring broke in. I'm still talking to vorsprung about this as I had to do this twice since install and that's not necessarily how spring steel should work. I think I may need a new spring... but if your smashpot is making noise or topping out, I'd absolutely assume it's the spring pre-load that's causing it. Oddly, not enough pre-load seems to make a similar clunk/thud near topout that having too much seems to. You can check the pre-load without completely removing the unit, but you need to follow the procedure for the spring swap... otherwise the shaft will drop into teh abyss and you'll need to remove it anyway.
when resquencing shims, i'm planning to move 3 main shims to decrease BO resistance.. i'm assuming that i move all 3 main shims between the spacer shim and the 8 clamp shims, or do i have a clamp shim between each of 3 main shims? just curious if you work at the path?
Any updates on the TruTune an secus?
I struggled this year to get my Zeb A2 feeling right. I’ve got a Secus on my pikes I...
Any updates on the TruTune an secus?
I struggled this year to get my Zeb A2 feeling right. I’ve got a Secus on my pikes I could swap over, but the main issue was ramp up - too much..
Otherwise I may just get some RXF38s. Got RXF36s and love them!
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it...
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
So did you find also the new boxxer too much progressive?
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it...
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
So did you find also the new boxxer too much progressive?
Yeah, but not as much ramp as the zeb.
I think they both have a lot of potential but personally I’m not as impressed with them out of the box as the reviews say.
Maybe it’s personally ride feel preference or maybe my Ohlins DH38 was just a better fork for me.
Hopefully get out on the zeb again soon and do some more testing. Going to shuttle today and try my Boxxer adjustments.
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it...
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
5w oil in the lowers is asking for premature wear of the stanchions, there just isn't enough film strength. If you found you need that thin of an oil it points to too tight bushings which is obviously the case more often than not with RS forks.
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it...
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
5w oil in the lowers is asking for premature wear of the stanchions, there just isn't enough film strength. If you found you need that thin...
5w oil in the lowers is asking for premature wear of the stanchions, there just isn't enough film strength. If you found you need that thin of an oil it points to too tight bushings which is obviously the case more often than not with RS forks.
This is a good point - the main reason I see people not getting travel is simply friction from the bushings! A 5wt oil might be OK in this specific application, because the bushings are so long that if the clearance is tight it can suit a lighter oil, which will be better at high speeds where a thick oil can create measurable drag. Its a combination of stanchion diameter + bushing length + clearance that determines the ideal viscosity. I usually find the stock dynamic "light" lube @ 50cSt is a really good balance for most forks but if the clearance is too close it could be slowing things down. 5wt can work but you need to make sure there is a decent amount of it - around 30cc would be the minimum I would be comfortable with. The downside to a thin oil is at those moments of zero speed (ie start and stop of the stroke) where the surfaces are sliding directly on each other, and not in the hydrodynamic regime there could be more friction but thats where the long bushings help the stanchion "float" off the bushing easier.
It's something I've looked in to a bit after the whole "Zebs are too progressive!!" noise started appearing a few months ago, and it for sure seems to be friction thats the biggest issue - I can bounce on a fork that I've freshly serviced (and sized the bushings) in the shop and bottom it out with the recommended pressure for my weight in the fork, so that doesn't seem like too much ramp in my eyes, personally
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown...
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable of putting energy into the bike like a 190-200lb expert pro-am rider.
That being said... the zeb is a great chassis and with some mods it can be excellent, even for light weight riders. Burnish the bushings, add a vorsprung secus, install a softer midvalve/checkvalve shim and run hsc all the way open. This should get you close to ideal.
A friend of mine had problems with reaching full travel on his Zeb. Even with no air in it the fork wouldn't bottom out. The damper ingested a lot of oil and in the end the bladder actually ruptured. Maybe check if you can achieve full travel at all?
A friend of mine had problems with reaching full travel on his Zeb. Even with no air in it the fork wouldn't bottom out. The damper...
A friend of mine had problems with reaching full travel on his Zeb. Even with no air in it the fork wouldn't bottom out. The damper ingested a lot of oil and in the end the bladder actually ruptured. Maybe check if you can achieve full travel at all?
They did have a batch of forks (thru covid) that used a different sealhead and it was able to ingest oil very easily. Everything before & after it has been serviced is much better for that. And charger 3 self bleeds excess oil too
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown...
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
The Luft Fusion mentioned above should be almost perfect for you. Not just for the mid stroke support but your weight the decreased compression in the lower leg should be noticeable. I haven't measured it on the zeb but on the lyrik debonair C1 at 160mm the difference is 8-10 kg at bottom out (just for the lower leg). On the zeb at 170 it's probably around 12-15 kg
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown...
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable...
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable of putting energy into the bike like a 190-200lb expert pro-am rider.
That being said... the zeb is a great chassis and with some mods it can be excellent, even for light weight riders. Burnish the bushings, add a vorsprung secus, install a softer midvalve/checkvalve shim and run hsc all the way open. This should get you close to ideal.
Shows how much things have changed that 150lbs is the "light end" of the spectrum? The damping in the charger 2.1 is fine at 150lb, its actually anyone heavier than that who might want to think about a firmer rebound tune. Just about everything these days is perfectly adequate down to around 130lb without needing drastic changes.
If you think the rebound is too slow its almost always the air pressure is too low and/or extra friction (which causes you to run the pressures too low...). If you are 10-20 psi below the suggested pressure it will never feel fast enough, even if you removed the damper completely! Because its the lack of spring force pushing it back out relative to your weight
Also please don't alter the check valve - its already super light and all that happens is increasing hysteresis or even creating knocking/harshness from the lag in valve opening. Those are quite specifically designed to be able to open and close super fast but without adding any resistance
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown...
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable...
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable of putting energy into the bike like a 190-200lb expert pro-am rider.
That being said... the zeb is a great chassis and with some mods it can be excellent, even for light weight riders. Burnish the bushings, add a vorsprung secus, install a softer midvalve/checkvalve shim and run hsc all the way open. This should get you close to ideal.
Shows how much things have changed that 150lbs is the "light end" of the spectrum? The damping in the charger 2.1 is fine at 150lb, its...
Shows how much things have changed that 150lbs is the "light end" of the spectrum? The damping in the charger 2.1 is fine at 150lb, its actually anyone heavier than that who might want to think about a firmer rebound tune. Just about everything these days is perfectly adequate down to around 130lb without needing drastic changes.
If you think the rebound is too slow its almost always the air pressure is too low and/or extra friction (which causes you to run the pressures too low...). If you are 10-20 psi below the suggested pressure it will never feel fast enough, even if you removed the damper completely! Because its the lack of spring force pushing it back out relative to your weight
Also please don't alter the check valve - its already super light and all that happens is increasing hysteresis or even creating knocking/harshness from the lag in valve opening. Those are quite specifically designed to be able to open and close super fast but without adding any resistance
the recommended pressure is 50psi and I use 48-49psi. I guess it's far from too low.
It's not silky smooth (after 100+hrs of riding and 1 rebuild) but the friction isn't that bad in my opinion. The breakaway force is definitely less than my Fox 36 (pre 2019)
I found a lot of posts talking about slow rebound. Most of them link to the new air spring though.
@carlinojoevideo How did the TrueTune and Secus work together by the way?
I haven’t installed it yet. Been busy riding the bike park on DH bike :-)
https://www.ebay.com/itm/124593036229
Those are very old news, I'm almost sure that he came up with that just before fox released 38, must have been pretty pissed they used the same design. All things considered it's pretty reasonably priced too.
The 38 uses the space between the inner tube and the stanchion to increase the lower leg volume. This also allowed to move lower the seal head, slightly increasing the neg.volume.
The Luft Fusion linked above used all the space between the inner tube and the stanchion to double the neg.volume. The trade off was that by using a smaller piston than stock the pressure requirements could exceed the maximum limit set by factory.
Both system also slightly increased positive volume. The inner cylinder is shorter than the stanchion: so the upper part of the pos.chamber has a larger diameter.
The new upcoming Luft Fusion uses a much simpler design that allows lower pressures (+25 / 35%) keeping the same performances. In addition, bottom-out resistance caused by air in the lower legs is reduced by 8-10 kg.
The old zeb is already quite progressive in long travel, the 2023 much more because the luftkappe style piston steals pos.volume to increase the neg. Plus the buttercups takes space in the lower leg.
The effect of lower leg volume is not shown in the charts.
Went coil, cant wait to ride it tomorrow.
I loved the Smashpot, but the heatshrink CONSTANTLY migrated down the spring on my 36. Besides that, best fork mod you can do IMO.
Good to hear, everybody loves it! they changed the shrinkwrap on fox 36's to an isolator for 2023, just FYI.
I had a secus in my A1 zeb ultimate and now a smashpot. Always ran it at 170mm. The secus was a fantastic upgrade to the zeb over the standard A1/B1 air spring and the smashpot was once again, a great upgrade over the secus. I can't say which one I preferred more as both were very good... In the end, I'd say the choice comes down to if you want to be weight concious and if you prefer the rebound feel or air vs coil. I don't think i was giving up anything in terms of performance between the two, just comes down to feel. Although, I will say that braking bumps with the smashpot are a non-issue... that part of it is sublime.
Regarding the smashpot... It's a great system overall, install is fiddly and there are a few things I can pass along from installing a few of them.
1) Heat the crap out of the heat shrink that goes on the inner shaft as it has a propensity to migrate down and cover the HBO holes (item 2.5 in the install instructions). There is some nuance to how you trim it on the top (where the upper travel shaft slots into the bottom), don't be afraid to having it tight, just about up against the outer shaft so that it clamps down and won't migrate. I would also cut the bottom of it a bit further away from the HBO supply holes then the instructions show as the lubrication can/will cause the heat shrink to migrate and loosen up slightly. The function this shrink wrap serves is noise reduction, and I haven't seen an increase in noise for cutting it back 1cm further away then the instructions show. If you're having an issue where you can't use the last 30mm of travel, this shrink wrap is most certainly migrated.
2) I'd go ahead and re-shim the HBO right off the bat, prior to the first install. They ship with 5 shims that you can re-sequence in the stack and move up above the clamp shim to get more/less hbo impact. (page 22 of the instructions) I would start by moving 2-3 of the shims above the clamp, leaving two in place up against the bottom out cone. I would also recommend using a 5wt oil to start with in lieu of the 20wt they suggest. I shred pretty decently for a 42 yr old, 180lb dude... and even with only running 2 hbo shims and 5wt oil, I do not have the HBO adjuster cranked down. I did elect to run a 50lb spring in lieu of the 45lb spring they suggested, which turned out to be the right choice... but still, I can't see where a situation in which running a spring below, would require that i run all 5 shims and/or 20wt oil. For reference, a buddy of mine that i ride with is running one of these as well, he's 6'7" - 270lbs and rides well... I still ended up swapping shims around for him leaving 3 in place and he is also running 5wt oil. Without doing that, the hbo engages pretty harshly and ramps up hard... If you are absolutely sending it to the level that the top 2-4% of riders at the whistler bike park are, maybe you'd need more hbo ramp... but I still doubt it.
3) Check the spring pre-load, check it again. Ride the fork for 4-5 rides, and check it once more. I found that it was changing as the spring broke in. I'm still talking to vorsprung about this as I had to do this twice since install and that's not necessarily how spring steel should work. I think I may need a new spring... but if your smashpot is making noise or topping out, I'd absolutely assume it's the spring pre-load that's causing it. Oddly, not enough pre-load seems to make a similar clunk/thud near topout that having too much seems to. You can check the pre-load without completely removing the unit, but you need to follow the procedure for the spring swap... otherwise the shaft will drop into teh abyss and you'll need to remove it anyway.
Awesome, thanks for the tips!
Regarding the lowers connection mod, I was thinking... Does it really do anything? Sure, it lowers the pressure build up in the spring side lower, but will increase it on the damper side. So is this a situation of lowering the spring side lowers force and increasing it on the damper side, effectively moving some apples from one pile to the other one?
Because of the large difference in sealed volume between the sides, I assume it makes the overall force generated by lower leg ramp...lower.
The seal head on the spring side effectively seals the entire stanchion, the damper side has tons more volume in comparison. The majority of casting ramp is generated from the spring side, that's what you feel. If one side is 6spi at bottom, and the other 2psi, what you are feeling is the 6psi. If you connect them and now they are both 3psi at bottom, that is a big improvement.
But the total volume stays the same and the surface area the pressure applies to also stays the same. That's why I'm wondering if the total force across both sides might actually stay the same...
when resquencing shims, i'm planning to move 3 main shims to decrease BO resistance.. i'm assuming that i move all 3 main shims between the spacer shim and the 8 clamp shims, or do i have a clamp shim between each of 3 main shims? just curious if you work at the path?
https://bikerumor.com/everflow-airlink-boosts-fork-leg-volume-for-easie…
Any updates on the TruTune an secus?
I struggled this year to get my Zeb A2 feeling right. I’ve got a Secus on my pikes I could swap over, but the main issue was ramp up - too much..
Otherwise I may just get some RXF38s. Got RXF36s and love them!
FYI, at 180 mm of travel and no spacers I don't have a problem using all (or almost all) the travel...
Hey, I did have good results with TruTune. Like you said, the problem isn’t really initial stroke so I have added the Secus. I think it would be nice, but I don’t really find a need for it.
Ive been testing the New Boxxer and found a few tricks that might cross over but haven’t tried yet on Zeb.
0-5wt oil on both sides. This is more for damper speeds.
Reducing the fork oil volume on both sides by 50% of recommendation. (I service my forks often, so I’m not worried about low oil volume).
Cutting off some the bump stop. The Boxxer bump stop is gigantic! I haven’t looked at the Zeb bumper yet.
The Zeb doesn't have a bump stop, just the rubber pads at the bottom
So did you find also the new boxxer too much progressive?
Yeah, but not as much ramp as the zeb.
I think they both have a lot of potential but personally I’m not as impressed with them out of the box as the reviews say.
Maybe it’s personally ride feel preference or maybe my Ohlins DH38 was just a better fork for me.
Hopefully get out on the zeb again soon and do some more testing. Going to shuttle today and try my Boxxer adjustments.
5w oil in the lowers is asking for premature wear of the stanchions, there just isn't enough film strength. If you found you need that thin of an oil it points to too tight bushings which is obviously the case more often than not with RS forks.
This is a good point - the main reason I see people not getting travel is simply friction from the bushings! A 5wt oil might be OK in this specific application, because the bushings are so long that if the clearance is tight it can suit a lighter oil, which will be better at high speeds where a thick oil can create measurable drag. Its a combination of stanchion diameter + bushing length + clearance that determines the ideal viscosity. I usually find the stock dynamic "light" lube @ 50cSt is a really good balance for most forks but if the clearance is too close it could be slowing things down. 5wt can work but you need to make sure there is a decent amount of it - around 30cc would be the minimum I would be comfortable with. The downside to a thin oil is at those moments of zero speed (ie start and stop of the stroke) where the surfaces are sliding directly on each other, and not in the hydrodynamic regime there could be more friction but thats where the long bushings help the stanchion "float" off the bushing easier.
It's something I've looked in to a bit after the whole "Zebs are too progressive!!" noise started appearing a few months ago, and it for sure seems to be friction thats the biggest issue - I can bounce on a fork that I've freshly serviced (and sized the bushings) in the shop and bottom it out with the recommended pressure for my weight in the fork, so that doesn't seem like too much ramp in my eyes, personally
As I light weight rider at 150lbs, I was never able to use the last 40-50mm of my 2021 Zeb 170mm. Like any long single crown fork, Zeb is very progressive near the end but it is a lot worse than other forks I have used (Lyrik, 36, 34). I can only get 90% of travel with 30% sag but it has too many drawbacks.
The lower leg volume is huge. The pressure ramps up so quickly that it doesn't make any difference how many volume spaces are used. I still get the same usable travel regardless of no of tokens. I tired to use the zip tie method to lower the lower leg pressure (equalise at 50% travel). It helps a bit. I get another 10mm.
The air spring doesn't have any mid-stroke support. Likely because my version has a smaller negative volume. When you land hard, it blows through a lot of travel and then feels like hitting a wall near the end. My fork has one compression adjustment only. Increasing compression damping doesn't help much. The compression damping tune is very light. On the flip side, this kind of light compression damping and lack of mid-stroke support setup is very enjoyable when charging root & rock section as long as it's not too steep.
The worst part is the rebound is not fast enough at fully open. 150lbs is on the light side of the spectrum but Ive never owned a fork that the rebound isn't fast enough for my weight.
likely not what you want to hear... but I wouldn't be running a zeb at 150lbs unless I was a world cup level rider and capable of putting energy into the bike like a 190-200lb expert pro-am rider.
That being said... the zeb is a great chassis and with some mods it can be excellent, even for light weight riders. Burnish the bushings, add a vorsprung secus, install a softer midvalve/checkvalve shim and run hsc all the way open. This should get you close to ideal.
A friend of mine had problems with reaching full travel on his Zeb. Even with no air in it the fork wouldn't bottom out. The damper ingested a lot of oil and in the end the bladder actually ruptured. Maybe check if you can achieve full travel at all?
They did have a batch of forks (thru covid) that used a different sealhead and it was able to ingest oil very easily. Everything before & after it has been serviced is much better for that. And charger 3 self bleeds excess oil too
The Luft Fusion mentioned above should be almost perfect for you. Not just for the mid stroke support but your weight the decreased compression in the lower leg should be noticeable. I haven't measured it on the zeb but on the lyrik debonair C1 at 160mm the difference is 8-10 kg at bottom out (just for the lower leg). On the zeb at 170 it's probably around 12-15 kg
Shows how much things have changed that 150lbs is the "light end" of the spectrum? The damping in the charger 2.1 is fine at 150lb, its actually anyone heavier than that who might want to think about a firmer rebound tune. Just about everything these days is perfectly adequate down to around 130lb without needing drastic changes.
If you think the rebound is too slow its almost always the air pressure is too low and/or extra friction (which causes you to run the pressures too low...). If you are 10-20 psi below the suggested pressure it will never feel fast enough, even if you removed the damper completely! Because its the lack of spring force pushing it back out relative to your weight
Also please don't alter the check valve - its already super light and all that happens is increasing hysteresis or even creating knocking/harshness from the lag in valve opening. Those are quite specifically designed to be able to open and close super fast but without adding any resistance
the recommended pressure is 50psi and I use 48-49psi. I guess it's far from too low.
It's not silky smooth (after 100+hrs of riding and 1 rebuild) but the friction isn't that bad in my opinion. The breakaway force is definitely less than my Fox 36 (pre 2019)
I found a lot of posts talking about slow rebound. Most of them link to the new air spring though.
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