Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127274
WORKBENCH ave you ever wonder ed wh y anyone would bother to ch ange their fork or shock sp rings? , Most of us know that a lte ring a sus pen sion component's sp ri ng preload affects ride height, but what ab out cha ng ing th e sp ri ng it self? What effect doe s th e len gth and/or rate of th e sprin g have o n yo ur bike' s setu p? A conversa tio n with a road race r a t the recent Mid-Ohio Nati onal left me in doubt of my kn owledge of su spen s io n co m p o ne n ts . Previ ousl y, I th o ught I had a handle o n handling, llut ' when this ra cer told me tha t h is forks were oversprung and I asked hi m why he didn 't just cut a n inc h r so out of the length, his answer affled me: " T ha t would make th e pring stiffer, not softer. " Huh? Thinking ab out it later, I realized ' th at he wa s right. I kn ew that th e arger the distance between the coils, he stiffer the spring rate, and vice ersa. So, if you have a fork spring '. ith a given coil distance, and you ompress it slightly by trapping it nder a for k leg's threaded cap, the oil dist ance, thus the spring rate, will e reduced slightly from what it was t full extension. • Now , if you were to slightly reduce hat spring's length by cutting a small on ion off one end, it would still xtend to the full length of the fork . hat this means is that with fewer oi ls sp rea d over the sa me distance, here wo u ld be a larger distance etween co ils th an th ere wa s befo re, .h us a stiffer spring rat e. Go t tha t? J How ever , if you were to cut too uch off th e spri ng, it would be .ho n er at fu ll extension ihan th e for k eg, thus yield ing ins ufficient ride reight. Con verse ly, insta lli ng too ong a sprin g mea ns that th e spring ay fu ll y co mp ress before the sus pen-jon com po nent does, th us li mi ting rave l. T h is is calle d " coi l bindi ng ," nd is the p rimary ca use of spring reakage. So, with spring len gth and coil istance stra ig ht in my m ind , 1 ca lle d arry Lan gl ey a t P ro gressive Su spen ion for an expe rt's o pinion. , Accor di ng to Langley, spring ra tes re .the si ngle most co n fus ing aspect f sus pe ns io n tu ning, as there are a u mber of .po p u lar misco ncep tions. .a ngley explained tha t spring makers an o n ly vary th ree fac to rs (in ad diion to th e o bvious sizing o f th e rin gs so th at they ph ysicall y fit rit%nto th e fo r k/shock) -- th e e-ng th, th e coil di stance and the wire Iia me ter. It turns o u t th at my understanding f len gth a n d co il d ist ance wer e orrect, so 1 asked Langley abou t wire ia me ter, Simply stated, he explained hat even th ough .a spring is coiled, t's still subject to the laws of physics, n this case leverage. Just as i t's harder o bend a th icker metal rod, it 's mo re iffi cult to co m press a sp ri ng mad e ,f thicker wire. Anoth er va riable i n suspension uning is the use of progressively o un d or dual-rate springs , and we'll iscuss tha t next week in Workbench. YA H orkbench is a week ly col umn dealng with motorcycle ma inten ance, erformanc e an d eq uipment. H ave ometh ing that Wo r kben ch ca n dd ress? Drop a line to Workb ench, ycl« News, P .O. Box 498, Long each, CA 9080 1-0498. AHA Presents The MO,.UI. c uNIT D Sl.; E #~<1 [)\>~~ LJ Glen H8Ien OHV Park San Bernardino, California August 25 &. 26, 1990 New!99! Yamaha Y1s iIId AWs On Display atMotoErpo One-day ticket: $18.00 Two-day tickets $23.00 YAMAHA OF COVINA BWR.OWER YAMAHA 10401AJoraa B IW. BelI11ower. CA 90706 (2131925-5097 BUR BANK YAMAHA 180 . B 1W Ul1lank BIW. BUl1lank. CA (BIB) B45-B73ll INn MOTORCYClE, INC. 7233 Canoga Ave. Canoga Par<, CA 91:m 181B) 346-3700 CONCORDYAMAHA 1891 Market st Concml. CA 94520 (415)79B-25BO sUNWEST CYClES 11 11 E.6thst Corona. CA 91720 (714) 1J5..n21 1011 W San Bemalllino Ad. . CcMna, CA 91722 181B I332-6249 YAMAHA OF CUCAMO NGA 9760 Foothill Blvd. Cucamonga. CA 91 m (714)987-2411 E LCAJON YAMAHA 660 8 Cajon Blvd. 8 Cajon, CA 92020 (619)442-3338 N ORTH COUNTY YAMAHA 1315 Nutmeg Ave. Escondido, CA 92026 {6191432-9501 JOHN BURR HONDA YAMAHA !lOOl sieml Ave. Footana, CA 92335 (7141823-1338 ORANGE COUNTY CYClE 13666 Hartlor B lvd. Garden Grove. CA 92643 (11 4) 530-7340 lEDEVANS MOTORCYClE SAlES 13347 W .Washingllll1 BIYd. Los Angeles, CA 90066 (21 ~ ~7906 DICKAUENS Y AMIHON 24601 An:h st Newhall, CA 91321 .1805) 259-8460 HONIYAMIKAW OF OCEANSIDE 1555 5. Hill st Oceanside. CA 92054 (61 9)722·1941 MONTClAIR Y AMAHA 111 95-1 Central Ave. 0nIari0. CA 91762 (714) 628-4748 YAMAHA OF REDLANDS 405 W Reda BIYd. . nds RecIands, CA 92373 (714)793-2473 MALCOLM SMITH MOTORCYClES 7563 Indiana . R iverside, CA~~ CAPITOL Y AMAHA 4622 Aliun BIYd. 5acramentD. CA 95842 ~1~~9200 . DAL£'S MO DERN CYClE 225 E. Baseline San Bernardino. CA 924 10 (7141 BB4-6464 .SAN DIEGO Y AMlsU2 4455 8 Cajon BIYd. San Diego, CA 92115 (6191 284-{)411 YAMAHA O FSAN WIS OBISPO 1357 Monterey st San Luis Cbspo, CA 93401 (B05] 54J.6723 SIMI VAllEY CYClES 2902 Los Angeles Ave. SimiValley. CA!00i5 (B05] 522-3434 lHOUSAND OAKS YAM/KAW - 2388 Thousand Oaks Blvd. Thousand Oaks, CA 91360 rn""·' j($"yi MAu oo~~~ ·· &PrI~S~ S~Satel ,a rl"9' ·1gt4 ~ Sept. g'atu ~ at eyteat ~ Shop Hours: TU9s-Fri 10a m- 6pm Saturday 10am-3pm ~- e o 660 W. 16th 5t ;. Long Beach. (213) 435-6.551 ell 90113 19