The story of: servicing my own bike and the Scott shock pump

Servicing your bike yourself, and then accidents you don't expect to happen, happens. That's Murphy's law, isn't it?

Scott 600 psi shock pump

I myself serviced my bike last week. The service is mainly washing the bike, rinsing the chain with diesel, rinsing the rear and front cassettes and lubricating all vital parts. I also checked the pressure of the shocks. My bike is a Scott Genius 30, and on Scott Genius bikes the rear shocks are somewhat special compared to other bike brands. The Scott Genius "Equalizer 2" rear shock consists of three chambers with extra high pressure, e.g. above 400 psi depending on your weight.

Valve blown off the hose

So I screwed the shock pump on to the rear shocks "positive chamber". Since the pressure was a little too low I started pumping. But when I almost had reached the desired pressure, the hose on the pump suddenly blew off with an angry "pffft", and the air in the rear shock escaped :(

Quite frustrating, sitting in Malawi with a broken Scott special-high-pressure-pump and no air in the rear shocks! Luckily I have other "normal" shock pumps, the kind that goeos up to 300 psi, and with one of them I managed to get the pressure up to 300 psi. However the rear suspension was still too soft, and the bike was also lower than normal. I went out for a ride, but after 20 minutes with the pedal constantly hitting rocks and small humps I realized  that the supension wasn't as all as it should be so I just hit my way back home.

Hose clamp fitted - ready for high pressure

So what do you do when you need a new Scott schock pump, and the nearest Scott dealer is 3000 kms away? Right, you might try to repair the broken pump. So I did, with a hose clamp I managed to tighten the hose onto the valve and I managed to get nearly the desired pressure into the rear shock - the only unexpected problem was that the hose clamp didn't resist pressure above 400 psi, so the hose blew "pffft" off the valve again emptying the shock for air once more. I refitted the hose clamp and desided that I'd better stop pumping at 400 psi before the hose blows off, although with my weight I should have had 437 psi.

I then went off for another ride into the bush, but it was exactly like the previous ride - pedals hitting the ground too often and almost throwing me off the bike at times :( With the rear suspention in this condition the bike was only good for riding on a plain surface, like a tar road.

..from the Scott manual

I had no biking for days until I, by e-mail assistance from Erik the mechanic in the shop in Oslo where I bought the bike (a million thanks to Erik at Torshov Sport Sykkel), found out what was wrong with the rear shock, and thus the cause of the low riding position: The air chambers on the Scott Equalizer 2 needs to be pumped up in the correct order,from 1 to 2, and there must be no air in #2 before #1 has been filled! The Equalizer2 has two valves, one for the positive chamber, and one for the negative chamber. So what had happende to me was that when the air escaped from the positive chamber, the suspention entered a "negative lock state", where the pressure in the negative chamber inhibited bulding up correct pressure in the positive chamber. Nasty little detail ! And this is not all mentioned in the Scott bike manual ! Scott should do some rewriting of the manual there...

So now I had a solution: to let out the pressure out of BOTH the chambers, then start refilling in the correct order: first the positive chamber, then the negative chamber. Now the rear suspension works almost as it should - except that the pressure is a little too low for my weight - and I can ride on trails without hitting the ground with the pedals. I'll be getting a new Scott pump by the end of this month, so things will work out smooothly, eventually ;-)

Trailbiker

Happy trailbiking :-)