Risse Astro 5 installation on 856

[Brian Nystrom]

I recently purchased an Astro 5 for my 856 through Bill Larson. I can't say enough good things about the service I've received from Bill. He's great to deal with!

I had some issues with the Astro shock and will detail them below for anyone else contemplating this upgrade.

1) Bill shipped the shock to me in the same box that Risse sent it to him. They included no instructions and no mounting hardware.

2) The shock requires the Freedom Plate and the bolt that comes with it. Risse does not automatically ship it with the shock, which seems ridiculous since you can't use it without one. I had to scrounge up a bolt and make a temorary spacer to fill the tapered hole in the strut while I wait for the F.P.

3) I noticed that the upper pivot of the shock did not pivot, either with finger pressure or when held with (padded) pliers. It appeared to be a tight press fit in the shock body. It seemed that it would be necessary to leave the upper pivot bolt in the frame loose and secure it with Loctite.

I called Risse and spoke with Brandon, who builds the air shocks. It turns out that there is a Teflon sleeve between the shock body and the upper pivot on the Pro Flex 855/856 versions of the Astro 5. It's a tight fit, but it will pivot when clamped in the frame. The upper mounting bolt should be cranked down tight.

4) My shock does not have noticeable detents at the 5 valve positions. Brandon said that the feel of the detents varies, though he's not sure why (his machinist claims that all the parts are to spec.). There are 5 separate oil orifices, so it's important that the adjustment lever be set only in the five positions specified. There is leeway of a few degrees, so if the detents can't be felt, they can be approximated and will work fine. I'll use it as-is, since there are probably only two positions that I'll use regularly and I won't have any trouble finding them by feel.

My overall impression is that this is a solidly built shock and it feels good on the trails, despite being new and somewhat stiff. The damping adjustment definitely works as advertised and the range it provides is good. When I ordered the shock, I specified my weight, X/C riding and that I like to run a soft spring with good damping. I don't know if they made any changes from a stock unit based on that, but it turns out that the ideal pressure (at least for now) is the same as my body weight (165#).

BTW, I started out using an old Topeak Shock Master Blaster pump with a stanadard Schraeder head, but I was having problems losing air. I emailed Topeak and inquired if the leakproof head on the newer pump could be installed on mine. Two days later, a new pump arrived in the mail! It's not as nice as some of the others on the market, but the new head works great and I can produce consistent shock pressure with it.

Here's the scoop on the Freedom Plate:

When it arrived, I was surprised to discover that it doesn't fill the tapered hole in the strut, but spans it. Considering this, I'm not so sure that it's absolutely necessary. It the 856 strut needs the FP, why doesn't the similarly shaped 855 strut? The FP does provide increased support for the shock in the vertical plane, but the 855 strut would benefit from this too. Regardless, it's well made and it comes with the bolt needed to mount the shock securely. When I installed mine, I left the spacers I used to fill the recess in the strut in place.

I also purchased one of Risse's inflation adaptors. It works exactly as described - NO leaks. It's very similar to the Fox adapter that comes with many pumps and if your pump has one, you would only need the female side of the Risse adapter in order to use it. The Risse adapter is better than the Fox adapter that came with my Topeak pump in one regard; the bleed hole is drilled off-center so that it can't be plugged by the tip of the valve stem. Good thinking!