My (well out of warranty) Reverb is due its annual rebuild and I wondered if it’s possible to buy the new SKF IFP, which I suspect will cure most of the problems with post sagging.

The blue bit in the top post on the right hand side for those who don’t know

Probably easier to ebay the old one and buy a new post.

It’ll probably cost me £80-90 to do that, whereas a new IFP is likely to be about £10!

Only 45mins to do the rebuild and £10 for seals.

You can almost guarantee that something will be a different size/diameter and new internals won’t fit in an old post.

…new SKF IFP, which I suspect will cure most of the problems with post sagging.

A bit of a tangent: I’ve been trying to figure out what the failure that causes sagging is, too. I’d be interested in your thoughts about it being the IFP seals that cause the sag problem.

If I’ve understood how the thing works properly, there’s never really any pressure differential across the IFP (other than enough to overcome the seal friction to move it), whereas the small, central piston has the weight of the bike on it (trying to draw air in) if/when the bike is lifted by the seat without the post at full extension, and supports the full weight of the rider otherwise. It’s true that the (old) IFP doesn’t really have anything keeping it square to the bore – maybe that’s it?

pull the saddle up when the post is dropped. Air will be sucked in and your post will now sag. Send back via shop. Recieve a NEW post. Job done.

Hoke’s right- until the original post is 2 yrs old SRAM will send you a new post under warranty.

Tillydog- it’s generally reckoned to be the fault of the ifp seal, although I see your point. I’ve heard some people have replaced it and the plastic guide rings with a quad seal, which is what I was planning to try until I saw RS have asked SKF to develop a better ifp.

it’s generally reckoned to be the fault of the ifp seal

Yeah, I’d heard it, but I don’t understand it.

Mrs Tillydog’s seatpost has developed a serious sag at ~18 months old, and I’m in two minds about whether it’s worth the hassle of returning it (and risking being charged for a repair), or if I should just fit new seals (it’s not worn) – or even try a ‘Russian Roulette’ bleed (taking the circlip out of the top and releasing the poppet valve).

Return it. At 18 months old you’ll almost certainly get a new post and if not they should ask you before starting a chargeable repair.

The reason I started taking mine apart is because I wanted to find a way to limit the extension, plus I like knowing how things work. When you see all the components it’s fairly obvious why they’re £200+

I have new IFPs on order, they are listed as A2+B1 meaning they should fit. However I think it might be an error, and haven’t had time to check the Sram documents yet, this is just going from Fishers order forms.

The latest A2 service kits we got have a new IFP that does retro fit older posts, it’s made of black plastic.. sorry advanced high tech polymer and is a slightly tighter fit, with just two o-rings and no glide rings.

Had mine replaced under warranty. Two and a half years old, very lucky boy.

Pigyn , do you have a link to where you ordered yours and how much was it ?