Fitted a reverb to my wife’s bike. Two slight issues have arisen.
First the button is very hard for her to push, small thumbs. Are they normally very firm to push?
Second her frame was built before droppers were even thought about (possibly).
When the post drops you can hear air hissing out of the headset area.
At least it’s almost waterproof.
Could this air pressure be contributing to the post being hard for her to drop, she doesn’t weight much? Could a hole be drilled into the bottom bracket shell to let the air out?

The button is hard to push, partly the reason I switched to a KS Lev. I suppose you could try using a Novyparts remote, but I’m not sure if it fixes the issue.

For the second issue, I have a friend that runs his at about 160psi with no problems; you could give that a go, assuming it is the air pressure that’s making the post hard to push and not the poppet valve opening incompletely (which would require a bleed).

Mine is fairly firm to press, but not that hard. RE the hissing, my old one never did it but the new (warrantied) one does. Same frame, so doubt it’s that. It also does it when I just move the whole thing up and down (i.e. the post and the outer) so I’m not too worried about it. I might be being naive though!

EDIT – There’s no difference in how hard it is to drop between the old one and the new one despite the hissing.

Dropping the post shouldn’t cause any air pressure change inside the frame…

The post doesn’t displace any air in the frame- it’s an air spring. If it is losing air into the frame then it should very quickly have stopped returning to full height. Not sure what’s causing the sound at the headset, could it be something like leaning on the post making the headset bearings move?

How hard the button is to push shouldn’t really correspond to the air pressure- I think changing the rebound speed may make pushing the button easier/harder as well, but I wouldn’t swear to it.

I found it was worth playing around with the position of the reverb remote- I thought it wasn’t up to much at first but eventually found a position that is really comfy. Not as nice as the shifter style mounts but butter than a lev/thompson. My OH has a Lev and a reverb and initially had similar problems (small thumbs) with the reverb but I think has no real preference now.

Okay time for a service i guess. It’s certainly causing a pressure to come out of the headset when it drops, you can feel it as well as hear it.
If the remote can’t be made easier it’ll be back on ebay.

The post doesn’t displace any air in the frame

Yes it does.

From a nearby thread:

The inner post (the part that moves) contains all the pressurised gubbins, but slides up and down inside the outer post (the bit that clamps in the seat tube). As it does this, the air it displaces comes in/out through a breather hole in the bottom of the outer post. There’s a felt washer inside that’s supposed to keep dirt out.

OP: This does not sound like a problem (IMHO).

Yes it does.

Aye, you’re right, engaged keyboard before brain. Amazed there aren’t any other breather holes anywhere on the frame. Shouldn’t be a problem in itself

I like to think of it as my bike sighing because it has to go back uphill 😀

No water bottle bolt holes that can be used as a ventilation option?

tillydog – Member
The post doesn’t displace any air in the frame
Yes it does.

From a nearby thread:

The inner post (the part that moves) contains all the pressurised gubbins, but slides up and down inside the outer post (the bit that clamps in the seat tube). As it does this, the air it displaces comes in/out through a breather hole in the bottom of the outer post. There’s a felt washer inside that’s supposed to keep dirt out.

That’s interesting , do you have a link to the article as I can’t understand how that would work .

It does displace air, but the amount is relatively small as the displacement is only the metal parts of the post that move as the post compresses. The compression of the airspring reduces the displacement alot, but it still happens.

It’s quite a hiss from the headset (never typed those words before) Bother bottle cages I think are in use. More of a waterproof frame design than we thought.

That’s interesting , do you have a link to the article as I can’t understand how that would work .

No specific article, but there’s quite a few explanations out there. Once you figure out how it works, it’s quite simple.

This and this are quite handy, as are the strip-down videos.

From the Pinkbike review:

Look at the full cross section at the top – When the post is compressed, the big green bit in the middle travels all the way to the left until it reaches the stop(a fat O ring near the air valve in the bottom of the post – far left in the picture). The air in the black space around the rod marked ‘air spring’ gets aqueezed out of a vent near the air valve when this happens.

That looks about right from what I’ve seen inside my own. will try removing a bottle cage, if it’s possible to run less pressure that might help her thumb with the lever.
.

The levers are a bit stiff, they always will be. Best things I found setting both mine up was to get it in a place/on an angle that I found easy (or as easy as it gets with all the bits on the bar!) to get to. Does she have room to fit right next to the grips? Not sure which lever you got but they can go on either side, found mine easiest to access on the left hand/front shifter side as I’m less likely to be shifting at the same time that side. Makes it much easier to handle. I was also convinced my newer dropper on the Juliana was broken, turns out how easily the post goes down can depend where you have your weight. I need to keep weight back on the Julie as opposed to the Superlight due to geometry, if she has her weight over the wrong part of the saddle it may seem ‘tougher’ to press the lever (that was my perception!). Turns out if I put my weight back it felt ‘easier’ to operate as the seat was going down straight away, rather than struggling and having to hold the lever for longer because I was waiting for it to finally go down!

I only mentioned the air pressure in response to the “she doesn’t weigh much” part; this would suggest not only the remote is hard to actuate, but the post as well. The air pressure in the spring does not affect the actuation force of the remote button in any way.

If you can push the post in using your hand it means the remote works correctly and dropping the pressure might help; if you are having trouble lowering the post maybe a remote bleed is in order.

The air pressure in the spring does not affect the actuation force of the remote button in any way.

Erm… at the risk of being branded an argumentative sod:

Yes it does.

Look at the detailed view on the bottom right of that picture from Pinkbike:

The pressure in the fluid from the remote (blue) on the top of the poppet valve (green) has to overcome the pressure from the pressurised fluid in the post (pink) on the bottom of the poppet valve for the valve to open. The diameters on each side are different, so it’s not a 1:1 ratio, but it it directly proportional. There is no other “return spring” in the system.

I’d echo the comments about getting the ergonomics right. I find the button below the bar much easier to use.

The only downside to running a lower pressure in the post that I can see is that the return speed will be slower.

My Yeti (ASR5 alu) used to do this – it must’ve been very airtight. I haven’t had the issue on any other frame but yes it’s a thing. I guess if it bothered you, you could consider drilling an air / water escape hole in the bottom bracket as many people do. As far as I can tell though, it never interfered with the functioning (the volume of air in the frame is fairly large compared to the amount the Reverb displaces so it’ll never really exert a pressure effect on the reverb).

Also at the risk of being branded argumentative (and I’ve thought more carefully this time!), I think the lever force should be largely independent of the air pressure. This is based on having serviced a few and i stand to be proved wrong, but it works in my head !

The return spring for the poppet is the small black void underneath it (opposite side to the ‘blue’ fluid. The fluid in the pink tube is not compressed by the air spring- the air spring acts on the ifp, outting pressure on the fluid in the black space above it. When the poppet is closed this is isolated from the pink tube, which is not under pressure (well, it’s under pressure frkm your weight acting on it but not the air spring). Open the poppet valve and the fluid can move from the pink tube into the black area because your weight pressurises it more than the ifp pushes back.

Any pressure on the poppet from the oil in the outer (black) tube should largely cancel out up and down as it’s coming in from the sides.

The fluid in the pink tube is not compressed by the air spring- the air spring acts on the ifp, putting pressure on the fluid in the black space above it. When the poppet is closed this is isolated from the pink tube, which is not under pressure

There is no “air spring” as such, other than the function of the post itself.

The air pressure acts on both the IFP and the ‘dry’ side of the main piston (orange bit with green dots !!!) which is what keeps the pink tube pressurised – Air added through the schrader valve at the end of the (hollow) main piston rod (incorrectly labelled a “air spring” in that picture) is free to enter the dry side of the piston through a hole (not shown) in the rod just below the piston, and in turn to the dry side of the IFP by holes (not shown) in the intermediate tube (pink thingy). The pink colour in the graphic implies there is oil behind the main piston, but there isn’t (the area to the left of the green dots should be coloured white…).

The air pressure on the ‘dry’ side of both the main piston and the IFP is the same (~~250 PSI). The post only extends when the poppet valve is open because of the difference in area between the main piston and IFP. (Main piston is smaller, IFP larger, so with the same air pressure acting on them, the fluid flows from IFP -> the main piston, extending the post.) The additional pressure on the main piston from weighting the saddle is enough to overcome this difference and have the fluid flow the opposite way when the valve opens.

The air space half way down the poppet valve may well offer some contribution to returning the remote button, but whenever I’ve pressed the remote on a post with no air in it, it hasn’t sprung back, so I think the main contribution is from the air pressure within the post.

/argumentative sod 😀

Good servicing video here https://www.youtube.com/watch?v=-w0X0-AOhRA

/argumentative sod

Hmmmm. Some interesting points- something doesn’t sit quite right with me though. May have to sit and mull it over for a bit.

Enjoying this!

My Yeti (ASR5 alu) used to do this – it must’ve been very airtight. I haven’t had the issue on any other frame but yes it’s a thing

On my old Turner frame if the seatpost was freshly greased and you dropped the post, when you undid the QR the post came back up out of the frame. Not quite back to where it started off but was still quite impressive.

OK, so, some points, what do you think?

-The diagram isn’t perhaps the most helpful- it’s components that are colour coded not ‘oil’ or ‘air’ spaces.

-I think the terminology ‘air spring’ is reasonable, isn’t it? The pressurised air volume is where the energy is stored when the post is compressed. The oil should be largely incompressible so surely it must be the air acting as the ‘spring’.

-The small space under the poppet valve is definitely a spring. Even if it’s only a secondary spring to help the poppet valve, there’s nowhere for the air to go under compression. Interesting to see you’ve found the remote doesn’t return with no air in as I’m pretty sure I’ve found it does. When you replace the poppet valve on reassembly there’s a little bit of a push to get the circlip in place before you’ve ever pressurised the post- I’ve also found the poppet valve can come out with some oomph (i.e. launched across the room) when the circlip is removed, even if the post has no pressure.

-I’m not convinced (but I’m not certain either way!) the oil in the pink tube is under pressure when the poppet is closed and no weight on the post. The oil in the outer tube above the IFP, yes, but the pink? Part of me thinks it must be to balance pressure across the green seal on the orange part but part of me thinks that’s what the seal is there to hold back!

I think I’m going to have to draw some diagrams to get this one straight in my head!

My 13 yo daughter can operate my both my reverbs and she is about as sturdy as a fairy wing so no issues with hard to push buttons.

OK, so, some points, what do you think?

The diagram isn’t the clearest, or even consistent in what is colour coded.

The air is acting as the spring, yes, but an “air spring” (or maybe gas spring) is a “thing” – constructed very similarly to the innards of the reverb. Just wanted to avoid any ambiguity about whether there was one of those inside.

I’ve also found the poppet valve can come out with some oomph (i.e. launched across the room) when the circlip is removed, even if the post has no pressure.

That’s because pressurised air has got into the oil side – there’s no way of releasing it safely (and yes, they come out like bullets! 🙂 )

Try these:

(poppet valve is drawn wrongly, but you can probably see that- all it does is open up a passage between inner and outer oil chambers.

There’s a 100-odd page thread on MTBR with various pictures and descriptions:

http://forums.mtbr.com/components/rockshox-reverb-thread-660853-96.html

Enjoy! 😉

Lubricate the trigger shaft with a bit of light fork oil or slick honey to make it move a bit easier,by gently pulling back rubber bellows-be aware this can be a flaff to pop back on though .
Maybe turn the pressure adjuster towards minus too to make it easier to get trigger moving.
Make sure the button is where the thumb actually is too-ie under the bars,straight inline with it’s more natural powerful movement.