1、Designation: F 2273 03An American National StandardStandard Test Methods forBicycle Forks1This standard is issued under the fixed designation F 2273; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods describe mechanical tests for deter-mining the following performance properties:1.1.1 Compression Load,1.1.2 Bending Lo
3、ad,1.1.3 Impact Resistance, and1.1.4 Fatigue Life.1.2 The values stated in SI units are to be regarded asstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate s
4、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesF 2043 Classification for Bicycle Usage3. Terminology3.1 Definitions of Terms Specific to This Standard
5、:3.1.1 bicycle fork (fork)the mechanism between the headtube and the front axle, including the steerer tube, crown, tripleclamps, shock absorbers, lower tubes, and upper tubes.3.1.2 steerer tubethe structural fork component typicallyhoused inside the bicycle head tube, connected to the forkcrown. Th
6、e steerer tube transmits steering inputs from the riderto the fork and connects the fork to the bicycle frame by meansof headset bearings.3.1.3 fork crown (crown)the primary structural fork com-ponent responsible for connecting the steerer tube to the forkupper tube(s) or fork blades.3.1.4 lower tri
7、ple clampSee fork crown. The lower crownof a two-crown suspension fork.3.1.5 upper triple clampthe secondary structural forkcomponent responsible for connecting the steerer tube to theupper tube(s).3.1.6 dropoutthe fork component used to support thefront wheel(s) at the axle(s).3.1.7 dropout centerl
8、inethe front hub mounting axis thatpasses through both right and left dropouts.3.1.8 tire clearancethe distance between the top surfaceof the tire and the bottom surface of the fork crown with nocompressive force applied to the fork.3.1.9 crown-to-axle clearancethe distance between thefork axle cent
9、erline and the bottom surface of the crown withno compressive load applied to the fork.3.1.10 head setthe bearing cup, cones, and other support-ing components for allowing rotation of the fork about thesteering axis.3.1.11 limit trip or stopa deflection of the fork, whichexceeds the allowable displa
10、cement values and causes themachine to stop running.4. Summary of Test Methods4.1 Compression Load TestThis test method compressesthe fork. The distance from the bottom surface of the crown tothe axle centerline is measured.4.2 Bending Load TestThis test method restrains a fork bythe steerer tube an
11、d applies a load perpendicular to the steerertube axis at the point on the dropout centerline centeredbetween the two dropouts. The deflection at the dropoutcenterline perpendicular to the steerer tube axis is measured.4.3 Impact Resistance TestThis test method restrains afork by the steerer tube in
12、 horizontal orientation; a weight isdropped from a prescribed height onto a fixture attached to thefork dropouts in line with the dropout centerline. Permanentdeflection at the dropout centerline perpendicular to the steerertube axis is measured. The ability of the connection betweenthe steerer tube
13、 and crown to support torque applied about theaxis of the steerer tube is also checked.4.4 Fatigue TestThis test method restrains a fork by thesteerer tube and applies a fully reversed load perpendicular tothe steerer tube axis at the point on the dropout centerline1These test methods are under the
14、jurisdiction of ASTM Committee F08 onSports Equipment and Facilities and is the direct responsibility of SubcommitteeF08.10 on Bicycles.Current edition approved July 10, 2003. Published July 2003.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.centered between the two dropouts. The test is sto
16、pped either atfailure as defined by the criteria below or at 250 000 cycles,whichever come first. The number of cycles is recorded.5. Significance and Use5.1 These tests are used to determine the performance of abicycle fork.6. Apparatus6.1 Compression Load Test:6.1.1 A fixture similar to Fig. 1 wil
17、l be required.6.1.2 The application of the load shall be applied to the topof the crown and along the centerline of the steerer tube (Fig.1).6.1.3 If necessary, then either a roller or linkage systemshall be used to allow translation of the dropouts while the forkis compressed.6.1.4 The distance fro
18、m the dropout centerline to the nearestsurface of the crown on steerer tube centerline shall bemeasured (Fig. 1).6.2 Bending Load Test:6.2.1 A fixture similar to that shown in Fig. 2 will berequired to position a fork such that the steerer tube axis ishorizontal and such that the fork is restrained
19、by the steerertube using bearings.6.2.2 Bearing separation shall be 150 mm as shown in Fig.2. Forks that require bearing installation not consistent withFig. 2 shall be constrained in a manner consistent with theirnormal use.6.2.3 The load shall be applied at the dropout centerline ina direction per
20、pendicular to the steerer (Fig. 2).6.2.4 The dropout centerline shall be free to translateparallel to the steerer tube with either a roller or linkagesystem.6.2.5 Deflection at the dropout centerline shall be measuredperpendicular to the steerer tube.6.3 Impact Resistance Test:6.3.1 A fixture simila
21、r to that shown in Fig. 2 will berequired to position a fork such that the steered tube axis ishorizontal and such that the fork is restrained by the steerertube using bearings. The fork shall be constrained so that itNOTEFor some fork designs, a dropout support that allows translation may be requir
22、ed.FIG. 1 Typical Compression Test ApparatusF2273032cannot rotate about the steerer tube axis and the dropoutcenterline is maintained horizontal.6.3.2 Bearing separation shall be 150 mm, as shown in Fig.3. Forks that require bearing installation not consistent withFig. 3 shall be constrained in a ma
23、nner consistent with theirnormal use.6.3.3 The application of the impact shall be perpendicular tothe steerer tube axis at the dropout centerline, centrally locatedbetween the dropouts (Fig. 2).6.3.4 A roller is required (Fig. 2) and must be of sufficientdiameter to ensure that the impactor comes to
24、 rest on the rollerfollowing impact.6.3.5 The height of the roller above the support base shouldbe such that the roller does not contact the base during the test.6.3.6 Deflection at the dropout centerline in a directionperpendicular to the steerer tube axis shall be measured.6.3.7 An apparatus capab
25、le of checking whether the con-nection between the steerer tube and crown can support aprescribed torque applied to the steerer tube about its axis isalso required.6.4 Fatigue Test:6.4.1 A fixture similar to Fig. 3 will be required to restrainthe suspension fork by the steerer tube using bearings as
26、shown.6.4.2 Bearing separation shall be 150 mm as shown in Fig.3. Forks that require bearing installation not consistent withFig. 3 shall be constrained in a manner consistent with theirnormal use.6.4.3 The force shall be applied at the dropout in a directionperpendicular to the axis of the steerer
27、tube.An actuator that iscapable of providing a fully reversed force of constant ampli-tude will be used.6.4.4 The dropout centerline shall be free to translateperpendicular to the direction of load application.6.4.5 The ability of the actuator to produce the requiredamount of force shall be verified
28、 per Practices E4.7. Test Specimens7.1 Preparation of Specimens:7.1.1 The forks shall be set to the maximum fully extendedlength.7.2 Fork Adjustment:7.2.1 The fork shall be tested with the standard spring rateand all preload and damping shall be adjusted to the minimumsettings.7.2.2 All fasteners sh
29、all be assembled to manufacturersspecifications.FIG. 2 Bending Load and Impact Test SetupF22730338. Calibration and Standardization8.1 The direction of load application shall be within 62.8.2 The accuracy of load application shall be within 0 % to+5 % of the specified value unless specified otherwis
30、e.8.3 The accuracy of all distance and displacement measure-ments shall be within 61 mm unless specified otherwise.9. Conditioning9.1 Tests are to be performed within the temperature rangeof 18 to 35C.9.2 All tests are to be performed on new forks withproduction stock settings except as noted.10. Pr
31、ocedure10.1 Compression Load Test:10.1.1 Adjust spring preload and damping to the minimumsettings.10.1.2 Install fork into the compression fixture.10.1.3 Measure the distance from the axle centerline to thenearest bottom surface of the crown on the steerer tubecenterline and record.10.1.4 Apply a sp
32、ecified compression load and hold formeasurement.10.1.5 Remeasure the distance from the dropout centerlineto the bottom of the crown and record.10.2 Bending Load Test:10.2.1 Adjust spring preload and damping to the minimumsettings.10.2.2 Install the fork into the restraining fixture and adjustthe pr
33、eload on the headset bearings as installed normally.10.2.3 Apply an initial load of 100 N. Zero the deflectionmeasurement apparatus.10.2.4 Apply an increasing load at a rate not to exceed 100N/s until a specified bending load is obtained. If manualloading is used, then the weight must be applied in
34、at least tenequal increments.10.2.5 Measure the deflection at the dropout centerlinebetween 60 to 90 s after the specified bending load is applied.10.2.6 Remove the load until a load of 100 N is obtained.10.2.7 Measure and record the fork deflection at the dropoutcenterline (permanent set) perpendic
35、ular to the axis of thesteerer tube.10.3 Impact Resistance Test:10.3.1 Install the fork in the fixture using typical headsetbearings. Slight over tightening of the bearings is acceptable toprevent the fork from freely rotating.10.3.2 Install the roller in the fork.10.3.3 Rest the weight on the rolle
36、r.10.3.4 Zero the deflection measurement apparatus.10.3.5 Raise the weight a specified drop height number oneabove the roller in the unweighted position.10.3.6 Release the weight, letting it freely fall and impactthe roller. The weight will bounce on the roller until it comesto rest. If the roller c
37、ontacts the support base, then the test isinvalid.10.3.7 Measure and record the permanent deflection perpen-dicular to the steerer tube with the weight resting on the roller.10.3.8 Repeat the test at a specified drop height number two.If the roller contacts the support base, then the test is invalid
38、.10.3.9 Check the connection between the steerer tube andcrown by applying a specified torque about the axis of thesteerer tube with the crown restrained. Record whether or notthe steerer tube rotated in the crown and if so, then the torquevalue that initiated rotation.FIG. 3 Fatigue Test SetupF2273
39、03410.4 Fatigue Test:10.4.1 Install a typical headset into the Head Tube Appara-tus (Fig. 3).10.4.2 Install a typical headset crown race onto the fork.10.4.3 Install the fork/crown race assembly into the headtube/headset assembly.10.4.4 The headset shall be adjusted using typical bicycleassembly pra
40、ctices. The bearings shall allow free rotation ofthe fork without any looseness or free play.10.4.5 Connect actuator mechanism to fork dropouts (Fig.3).10.4.6 Begin applying a specified fully reversed sinusoidalload at 1 Hz and measure the peak displacements after 1000cycles. If desired, then gradua
41、lly increase the frequency untilthe running peak displacements determined as the peak dis-placements after an additional 1000 cycles of loading arewithin 63 % of the displacement at 1 Hz. (See Fig. 4.)10.4.7 The load shall be monitored to an accuracy of 0 %,+5.0 % through either strain gages attache
42、d to the fork or a loadcell. Likewise, the displacement shall be monitored to within5%.10.4.8 The test shall be stopped when failure occurs. Inusing force control to perform the test, failure is determinedthrough a multistep procedure.10.4.8.1 The first running peak displacements are deter-mined as
43、the peak displacements achieved after the first 1000cycles of load. When either of the peak displacements increaseby 0.76 mm compared to the corresponding first running peakdisplacements, the test is stopped.10.4.8.2 The test is restarted to determine second runningpeak displacements achieved after
44、the first 1000 cycles ofadditional load. During this period, a visual inspection isperformed. If any cracks in structural components are apparent,then the test is stopped and the number of cycles to failure isrecorded as the total number of cycles to reach the first stop. Ifno cracks are apparent, t
45、hen the test is continued and stoppedwhen either of the peak displacements increase by 0.76 mmcompared to the corresponding second running peak displace-ment.10.4.8.3 The test is restarted to determine third running peakdisplacements achieved after the first 1000 cycles of additionalload. During thi
46、s period, a visual inspection is performed. Ifany cracks in structural components are apparent, then the testis stopped and the number of cycles to failure is recorded as thetotal number of cycles to reach the second stop. If no cracks areapparent, then the test is continued and stopped when either
47、ofthe peak displacement increases by 0.76 mm compared to thecorresponding third running peak displacement. Failure isrecorded as the total number of cycles to reach the third stop.10.4.9 The test may be suspended at 250 000 cycles if thisnumber of cycles is achieved before failure occurs.10.4.10 If
48、the machine is shut down for any reason before astop is reached, then no settings should be changed when thetest is resumed.10.4.11 Record the peak displacements after 1000 cycles at1 Hz; the running peak displacements after an additional 1000cycles if the frequency of the test is greater than 1 Hz;
49、 the totalnumber of cycles to each of the stops; the results of the visualinspection following each of the stops; and the number ofcycles to failure.11. Report11.1 Atest report shall be prepared to include the following:11.1.1 Applicable Test Method Specification,11.1.2 The manufacturer of the fork(s) tested,11.1.3 The model, year, and serial number of the fork(s)tested,11.1.4 The date and location of the test,11.1.5 The name of the person and entity conducting thetest,11.1.6 A description of all instruments used to make loadand distance or displacement measuremen
