DV-22 rear suspension: sand -> grinding noises
02-18-19, 03:21 PM
#1
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Bikes: HP Velotechnik Streetmachine GTE, 2015 Devinci Silverstone SL4, 2012 Cannondale Road Tandem 2, Circe Morpheus, 2021 Rose Backroad, 2017 Devinci Hatchet
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DV-22 rear suspension: sand -> grinding noises
Hello all winter basement mechanics (and everyone else) 
Another of my deferred maintenance projects is related to the DNM DV-22 coil/oil-damper rear suspension element on my recumbent. I once (!) rode it for a little bit in mild rainy weather without fenders and picked up a lot of sand on the way. Some of that made its way onto the coil spring and the damper surfaces.
Ever since, I can hear some small grinding sounds from the suspension when it is in action.
I cleaned out the bike carefully, including all pivots and mounting points, and - obviously - finally mounted full-coverage fenders. I cannot spot any sand or dirty on the suspension element anymore, but still get those noises. It almost sounds like parts of the sand might be in the oil flow passing the valve (is that possible???), some sounds more like harder scratching. I cannot see any scratches (or any other irregularities) on the damper surfaces.
Two questions:
(a) Is this going to be a problem soon(er than standard life)?
(b) Can I do something about this?
Thanks!
Another of my deferred maintenance projects is related to the DNM DV-22 coil/oil-damper rear suspension element on my recumbent. I once (!) rode it for a little bit in mild rainy weather without fenders and picked up a lot of sand on the way. Some of that made its way onto the coil spring and the damper surfaces.
Ever since, I can hear some small grinding sounds from the suspension when it is in action.
I cleaned out the bike carefully, including all pivots and mounting points, and - obviously - finally mounted full-coverage fenders. I cannot spot any sand or dirty on the suspension element anymore, but still get those noises. It almost sounds like parts of the sand might be in the oil flow passing the valve (is that possible???), some sounds more like harder scratching. I cannot see any scratches (or any other irregularities) on the damper surfaces.
Two questions:
(a) Is this going to be a problem soon(er than standard life)?
(b) Can I do something about this?
Thanks!
03-02-19, 04:09 PM
#2
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Maybe there's nothing that can be done with this and/or it's not really an issue. For me, it definitely isn't a pressing issue, but in case it could become one I would like to do everything to avoid it becoming one sooner than usual. Just to try again - anyone have any experience/input on this?
Thanks!
Thanks!
03-02-19, 05:22 PM
#3
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If you've thoroughly cleaned it you shouldn't have any noises. If you're still hearing crunching/grinding, it ain't clean. I use pressure hose occasionally and wax on the visible parts of the cylinder because more sand will stick to an oily surface and eventually destroy the seal. Unlike heavy equipment cylinders, there aren't any dirt sweeps built into the seals on these bikes. (subject to change and that info might be outdated). I ride on the beach a lot and am always dealing with sand getting into everything. A baby bottle brush works great on derailleurs front and rear. Wax on the exposed cylinders, both fork and frame, helps with longevity of parts. Some friends of mine use metal polish, but I prefer paste wax. HTH
