Cycle News - Archive Issues - 1990's

WORKBENCH By Brian Catterson Damping, not dampening ast week in Workbench we con cluded our discussion of springsand spring rates and touched on the principles of hydraulic damping. This week, as promised, we'll begin to explain how you can go about dialing in your compression and rebound damping. These days, most din and street bikes have some type of extemal damping adjustment(s) on their fork and/or shock(s). Motocrossers and race-replica street bike s lik ely hav e 'a dj ustable compression and rebound damping at both front and rear, while les ser machines may only have adjustable rebound damping. These adjustments are typicaly located at the top and/or bottom of the fork or shock, although in some cases, such as with Marzocchi's Ml R fork, the adjustments may only be found in one leg. • As we told you last week, compression damping controls the speed with which the suspension component bottoms, while rebound damping determines the speed with which it returns to full extension. At the risk of over-simplification; compression damping is usually most noticeable over single large bumps, while rebound damping is typically felt over series of small bumps. Let's begin with compression damping . If your suspension freq u en tly bottoms, you likel y have too little compression damping. Conversely, if your suspension barely moves when you encounter a bump, and the full force of the hit can be felt through the handlebars, you likely have too much compression damping. Adjust the screw which controls compression damping one step at a time until it feels right. You want the suspension to bottom on only the largest bumps, and then to do so progressively, rather than abruptly. Rebound damping is a bit more difficul t. If the quality of your bike 's ride deteriorates from the beginning to the end of a series of bumps, chances are yo u r rebound damping is the culprit. This means that when your suspension compresses as it encounters a bump, it either doesn 't rebou nd quickly enough, or it rebounds too quickly, to prepare itself for the next bump. The resulting rough ride is commonly referred to as "pa cking up." However, since the above scenario can also be triggered by inadequate compression damping, make your compression damping adjustments first. One common misconception is that the rougher a track is, the stiffer the suspension should be. This is actually quite backwards. In the case of a road race bike, for example, a smooth track requires very little from the suspension, other than to control the pitch of the bike as it brakes or accelerates, so you'd want stiff damping to minimize those forces. In the case of a rough track, the damping should be set softer so that the suspension will move faster and the wheels will stay in contact with the ground If you reach the limit(s) of your adjustment(s) and the ride still doesn't feel q uite right, you'll probably need :to change the weight of your fork or shock oil. Of course, if your suspensio n components are non-adjustable, this is the only way you can make any damp"ing changes without maki ng major modifications (such as changing the size of the holes in your damping rods). 0' L Won.bmcb ia • wftiJy col1UDll deal.iDl with mo lOl'qde . lDauumaoa. pnfonDllD« aod eqaipmmt. Ba"t 80methinc daatWorUmcb caD addaaI? Drop a linc to Workbmcb. Cycle N ..... P.O. . .. .... l.oDo _ CA _ ....... Plan now for THE DUNLOP 500/125CC NATIONALS AT UNADILLA 'J!!I JtU1 $ '" H CTI O H E D -OCTOBER 13-14, 1990- Thl U ..dill8 VIIIIJ Sports Clotlr, Inc. RU, lew I.lil, lie. York. TICIET PIIICES: .'f8,DUN.£OP SZSperpo1lI.) BINGHAMTON Clllldrln-12 Ind undllf--lree I aa:otI1lIniidbyanadJlL Tdll Illhe gale, no sal ..... c...lnt-{Payllbla ""'" arrival) "~hl-f lllliy ca-.;ng tID ...alI«1JC IlE'o'ERAOESlUDWBlI S 10~n ~ hl-- _ ~ /ItijjiiS&I C I r \: o R .\ Wine Cellan T_ SCOTT U ~ HiIsidI ~ lFt'(uceAa.1.(MED. CDlQNATEDAAU I.MItD:TWO&-NCICS. CAJeCJI.t, PE PERSC:l"fli ~ ' R F"", Parl

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