1、Designation: F2273 11An American National StandardStandard Test Methods forBicycle Forks1This standard is issued under the fixed designation F2273; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 Load,
3、1.1.3 Impact Resistance, and1.1.4 Bending Fatigue Life (followed by Impact Resis-tance).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 thi
4、s standard to establish appro-priate safety 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 MachinesF2043 Classification for Bicycle Usage3. Terminology3.1 Definitio
5、ns of Terms Specific to This Standard:3.1.1 bicycle fork (fork)the mechanism between the headtube and the front axle, including the steerer tube, crown(s),shock absorbers, lower tubes, and upper tubes.3.1.2 steer tubethe structural fork component typicallyhoused inside the bicycle head tube, connect
6、ed to the forkcrown. The 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(s), or crown(s)the primary structuralfork component responsible for connecting the steerer tube tothe fork upper tube(s) o
7、r fork blades. Some suspension forkshave an upper and a lower crown, while other forks have onlyone.3.1.4 dropoutthe fork component used to support thefront wheel(s) at the axle(s).3.1.5 dropout centerlinethe front hub mounting axis thatpasses through both right and left dropouts.3.1.6 tire clearanc
8、ethe distance between the top surfaceof the tire and the bottom surface of the fork crown with nocompressive force applied to the fork.3.1.7 crown-to-axle clearancethe distance between thefork axle centerline and the bottom surface of the crown withno compressive load applied to the fork.3.1.8 head
9、setthe bearing cup, cones, and other support-ing components for allowing rotation of the fork about thesteering axis.3.1.9 limit trip or stopa deflection of the fork, whichexceeds the allowable displacement values and causes themachine to stop running.3.1.10 suspension forkfront fork incorporating c
10、ompli-ance in the axial direction, parallel to the steer tube.3.1.11 rigid forkfront fork that is not designed to becompliant in the axial direction.4. Summary of Test Methods4.1 Compression Load TestIn this test the fork is com-pressed in a direction parallel to the steerer tube. The distancefrom t
11、he bottom surface of the crown to the axle centerline ismeasured.4.2 Bending Load TestIn this test the fork is restrained bythe steerer tube and a load is applied in a direction perpendicu-lar to the steerer tube axis, at the midpoint of the dropoutcenterline. The deflection is measured at the dropo
12、ut centerlinein a direction perpendicular to the steerer tube axis.4.3 Impact Resistance TestIn this test a fork is fixturedwith the steerer tube oriented horizontally, and supported bybearings. A weight is dropped from a prescribed height onto afixture attached to the fork dropouts in line with the
13、 dropoutcenterline. Permanent deflection is measured at the dropout1These test methods are under the jurisdiction of ASTM Committee F08 onSports Equipment and Facilities and is the direct responsibility of SubcommitteeF08.10 on Bicycles.Current edition approved March 1, 2011. Published June 2011. Or
14、iginallyapproved in 2003. Last previous edition approved in 2003 as F2273 03. DOI:10.1520/F2273-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc
15、ument Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.centerline in a direction perpendicular to the steerer tube axis.The ability of the connection between the steerer tube andcrown to support torque
16、applied about the axis of the steerertube is also evaluated.4.4 Fatigue Plus Impact TestIn this test a fork is re-strained by the steerer tube and a fully reversed load is appliedin a direction perpendicular to the steerer tube axis at themidpoint of the dropout centerline. The test is suspended and
17、the sample inspected if displacements exceed a prescribedvalue, or after the specified number of cycles, whichever comesfirst. If the test sample reaches the target cycle count, it issubsequently subjected to a frontal impact as described in 4.3.If inspection of the sample reveals a structural crack
18、 or fracturebefore reaching the target cycle count, or if the specifieddisplacements during the cyclic loading are exceeded, the testis concluded and the number of cycles reached before failure isrecorded.5. Significance and Use5.1 These tests are used to determine the conformance of abicycle fork s
19、ample to a standard specified for each useclassification.6. Apparatus6.1 Compression Load Test:6.1.1 A fixture similar to Fig. 1 is required.6.1.2 The load shall be applied to the top of the crown andalong the centerline of the steerer tube (Fig. 1).6.1.3 If necessary, either a roller or linkage sys
20、tem shall beused to allow translation of the dropouts while the fork iscompressed.6.1.4 The distance from 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 is required t
21、oposition a fork such that the steerer tube axis is horizontal andsuch that the fork is restrained by the steerer tube usingstandard headset 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
22、a manner consistent with theirnormal use.NOTEFor some fork designs, a dropout support that allows translation may be required.FIG. 1 Typical Compression Test ApparatusF2273 1126.2.3 The load shall be applied at the dropout centerline ina direction perpendicular to the steerer (Fig. 2).6.2.4 The drop
23、out 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 similar to that shown in Fig. 2 is required toposition
24、a fork such that the steered tube axis is horizontal andsuch that the fork is restrained by the steerer tube usingstandard headset bearings. The fork shall be constrained so thatit cannot rotate about the steerer tube axis and the dropoutcenterline is maintained horizontal.6.3.2 Bearing separation s
25、hall 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.6.3.3 The application of the impact shall be perpendicular tothe steerer tube axis at the midpoint of the dropout centerline(Fig. 2).6
26、.3.4 Aroller shall be used (Fig. 2) and shall be of sufficientdiameter to ensure that the impactor comes to rest on the rollerfollowing impact.6.3.5 The height of the roller above the support base shall besuch that the roller does not contact the base during the test. Ifthe roller does contact the b
27、ase during the test, the test shall beruled invalid.6.3.6 Deflection shall be measured at the dropout centerlinein a direction perpendicular to the steerer tube axis.6.3.7 An apparatus capable of checking whether the con-nection between the steerer tube and crown can support aprescribed torque appli
28、ed to the steerer tube about its axis isalso required.6.4 Fatigue Plus Impact Test:6.4.1 A fixture similar to Fig. 3 is required to support thefork by the steerer tube using bearings as shown.6.4.2 Bearing separation shall be 150 mm as shown in Fig.3. Forks that require bearing installation not cons
29、istent 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 tube.An actuator that iscapable of providing a fully reversed force of constant ampli-tude shall be used.6.4.4 The
30、 dropout centerline shall be free to translateperpendicular to the direction of load application.6.4.5 The ability of the actuator to produce the specifiedforce shall be verified per Practices E4.FIG. 2 Bending Load and Impact Test SetupF2273 1137. Test Specimens7.1 Preparation of SpecimensThe forks
31、 shall be set to themaximum fully extended length.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 shall be assembled to manufacturersspecifications.8. Calibration and Standardizat
32、ion8.1 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 otherwise.8.3 The accuracy of all distance and displacement measure-ments shall be within 61 mm unless specified otherwise.9. Conditioni
33、ng9.1 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. Procedure10.1 Compression Load Test:10.1.1 Adjust spring preload and damping to the minimumsettings.10.1.2 Install fork into the c
34、ompression 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 specified compression load and hold formeasurement.10.1.5 Remeasure the distance from the dropout centerlineto the bottom of the c
35、rown 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 preload on the headset bearings as installed normally.10.2.3 Apply an initial load of 100 N. Zero the deflectionmeasurement appara
36、tus.10.2.4 Apply an increasing load at a rate not to exceed 100N/s until the specified bending load is obtained. If loading is tobe applied manually using weights used, the weight must beapplied in at least ten equal increments.10.2.5 Measure the deflection at the dropout centerlinebetween 60 to 90
37、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 change in fork deflection(permanent set) at the dropout centerline in a direction perpen-dicular to the axis of the steerer tube.10.3 Impact Resistance Test:10.3.1 Ins
38、tall the fork in the fixture using standard headsetbearings. Constrain the steerer tube to prevent rotation of thefork in the bearings.10.3.2 Install the roller in the fork.10.3.3 Rest the weight on the roller.10.3.4 Zero the deflection measurement apparatus at thedropout centerline, in the vertical
39、 direction.10.3.5 Raise the weight to the first specified drop height (thedistance between the bottom of the weight and the top of theroller, with no weight resting on the roller.10.3.6 Release the weight, letting it freely fall and impactthe roller. The weight will bounce on the roller until it com
40、esto rest.FIG. 3 Fatigue Test SetupF2273 11410.3.7 Measure and record the permanent deflection perpen-dicular to the steerer tube with the weight resting on the roller.10.3.8 Repeat the impact on the same sample using thesecond specified drop height.10.3.9 Check the connection between the steerer tu
41、be andcrown by applying the 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.10.4 Fatigue Plus Impact Test:10.4.1 Install a typical headset into the Head Tu
42、be 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 Adjust the headset using typical bicycle assemblypractices. The bearings should allow free rotation of the forkwithout excess radial
43、movement.10.4.5 Connect the actuator mechanism to the fork dropoutsaccording to the fork manufacturers specification (Fig. 3).10.4.6 Begin applying the specified fully reversed sinusoi-dal load at a frequency of 1 Hz. Stop the test after 1000 cyclesand retighten all headset components. Restart the t
44、est andmeasure the peak displacements after 1000 cycles. If desired,then gradually increase the frequency until the running peakdisplacements are within 63 % of the displacement at 1 Hz.Monitor the load to ensure an accuracy of 0 %, +5.0 %through either strain gages attached to the fork or a load ce
45、ll.Monitor the displacement with an accuracy of 65%.10.4.7 Conclude the test if an obvious structural failure isobserved before 100 000 cycles, and report that the samplefailed the test.10.4.8 Interrupt the test if the running displacements (ineither direction) increase by 40% for suspension-type fo
46、rks or20 % for rigid forks, relative to the displacements recordedafter the initial 1000 cycles of operation. Inspect the sample forstructural cracks or fracture. If any are found, conclude the test,record the cycle count, and report that the sample failed thetest. Cracks in paint or clearcoat do no
47、t indicate a structuralfailure. If no structural cracks or fractures are found, continuethe test to complete 100 000 cycles, provided that the displace-ments remain within the limits of 40 % for suspension forks or20 % for rigid forks.10.4.9 Stop the test after 100 000 cycles. Inspect the samplecare
48、fully for structural cracks or fractures. Record and reportthese observations.10.4.10 If the sample completes 100 000 cycles withoutexceeding the displacement limits noted above, and if nostructural cracks or fractures can be observed, perform theimpact resistance test described in 10.3, using the a
49、ppropriatedrop height for the specified classification.10.4.11 Inspect the sample carefully for structural cracksand record all observations.10.4.12 A passing result is obtained if the fork meets thespecified requirements for the impact test following an impactfrom the specified drop height.10.4.13 If the machine is shut down for any reason otherthan a displacement limit trip during the test, then no settingsshould be changed when the test is resumed.11. Report11.1 Atest report shall be prepared to include the following:11.1.1 Applicable Test Method Specif
