FIG. 2. As used in this disclosure, the expression “reach point” refers to a coordinate along an axis 233 parallel to a line through the front and rear axles of the bicycle. In this disclosure, where a first reach point is said to be “closer to,” “between” or otherwise described in spatial relation to a second reach point, it should be understood, that only a spatial relationship along axis 233 is being described. According to various embodiments, R(f1) is between the reach point of the bottom bracket shell (R(bb)) and the reach point of head tube (R(ht)).

In the illustrative example of FIG. 2, first fore pivot assembly 231 comprises a structure on front triangle 205 which is pivotably connected to a second end 253 of a tension bar 251. Depending on the geometry of the frame, first fore pivot assembly 231 may be connected to head tube 207 at one or more top tubes (for example, top stays 271a and 271b of top tube assembly 271 in FIG. 2), or other mounting point on front triangle 205. In certain embodiments, for example, embodiments with a crossing down tube (such as used on SE Bikes' Quad Series frames) first fore pivot assembly 231 may be mounted on a down tube.

In certain embodiments, first fore pivot assembly 231 comprises a clevis bracket comprising a u-shaped section of material with two parallel sides with one or mating pairs of holes proportioned to accommodate a clevis pin. In some embodiments, the clevis pin may be a press-fit pin, or a pin utilizing a snap ring or circlip. In various embodiments, the clevis pin comprises a smooth portion providing a surface upon which the tension bar can rotate and a threaded end which threads into first fore pivot assembly 231. In this way, the clevis pin can be removed and replaced for repairs and adjustments trailside. In various embodiments, first fore pivot assembly 231 comprises one or more bushings or bearings attached to front triangle 205 (for example, at a top tube of the front triangle) configured to pivotably retain an axle connected to second end 253 of tension bar 251. In embodiments in which first fore pivot assembly 231 pivotably connects with second end 253 of tension bar 251 through a clevis pin, axle or other rotational structure, first fore pivot assembly 231 may include one or more of a tension spring or bushing on the clevis pin or axle to minimize rattle during heavy use. In certain embodiments, tension bar 251 may be integral with front triangle 205, and first fore pivot assembly 231 comprises a region of material of high flexibility, such as a thin, substantially flat section of carbon fiber, such as used in “flex-stay” rear suspension designs in which a flexible section of material replaces a bearing or other rotational pivot component.

Referring to the illustrative example of FIG. 2, tension bar 251 comprises a section of substantially rigid material (for example, aluminum, steel, carbon fiber or titanium tubing) with a first end 252 and a second end 253. In some embodiments, to improve stand-over clearance, tension bar 251 comprises one or more bends 255. In some embodiments, tension bar 251 may curve along some or all its length. In certain embodiments, the distance between first end 252 and second end 253 may be adjustable, for example, by making tension bar 251 a multi-part structure in which two or more sections of material telescope relative to one another and can be locked into different positions. Depending on embodiments, making the length of tension bar 251 adjustable may enhance fine-tuning of the kinematics by which the effective seat angle and reach point of the saddle change in response to extending and compressing the dropper seat post.

As previously noted, second end 253 of tension bar 251 is pivotably connected to a first pivot assembly 231, and first end 252 of tension bar 251 is pivotably connected to an upper portion 261 of a telescoping seat post assembly 260. According to various embodiments, telescoping seat post assembly 260 comprises an upper portion 261 and a lower portion 262. Lower portion 262 comprises a hollow section of material (typically an aluminum tube sealed at a lower end) which is pivotably connected to frame 200 through aft pivot assembly 221. Upper portion 261 comprises a second hollow section of material (again, typically a section of aluminum tubing) proportioned to slide along an interior surface or exterior surface of lower portion 262. A damped spring (for example, a gas or coil spring with a hydraulic or pneumatic damper) with remotely actuated (for example, through a cable, hydraulic line or electronically) release is disposed within the interior of upper portion 261 and lower portion 262. When the release is actuated, upper portion 261 is free to move telescopically relative to lower portion 262. For example, if a rider applies her weight to saddle 263 while the release is engaged, telescoping seat post assembly compresses under the force of her weight, moving upper portion 261 closer to bottom bracket shell 215. Similarly, if the rider raises the seat points of her body while the release is engaged, the damped spring pushes upper portion 261 away from lower portion 262, causing upper portion 261 to extend and put saddle 263 in a higher seat position. The rider can lock saddle 263 into a new height by disengaging the release.

Referring to the explanatory example of FIG. 2, first end 252 of tension bar 251 is pivotably connected to upper portion 261 of telescoping seat post assembly 260. In certain embodiments, tension bar 251 is directly connected to upper portion 261 (for example, through a clamp or braze-on on exterior of a surface which slides in or over lower portion 262. In some embodiments (for example, where mounting a pivot would interfere with, or reduce, the travel of telescoping seat post assembly 260, first end 252 of tension bar 251 may be indirectly pivotably connected to upper portion 261, connecting through a pivot disposed on a saddle clamp, or a portion of saddle 263 (for example, to the saddle rails).

In some embodiments, tension bar 251 is pivotably connected to upper portion 261 of telescoping seat post assembly 260 through an axle-based connection (for example, through a clevis on either tension bar 251 or upper portion 261 configured to accommodate a clevis rod end on either tension bar 251 or upper portion 261, and to pivot on a clevis pin running through the clevis and clevis rod end). In some embodiments, tension bar 251 is pivotably connected to upper portion 261 through a section of flexible material (for example, a thin section of carbon fiber) integral with upper portion 261, saddle 263 or a saddle clamp connecting upper portion 261 to saddle 263.

As shown in the explanatory example of FIG. 2, frame 200 comprises an aft pivot assembly 221, which is located at a reach point (R(ap)) which, when measured along axis 233, is closer to the reach point (R(bb)) of the bottom bracket than the reach point R(f1) of the first fore pivot point. The lower portion 262 of telescoping seat post assembly 260 is pivotably connected to frame 200 through aft pivot assembly 221. According to various embodiments, aft pivot assembly 221 allows lower portion 262 to pivot across a 15-30 degree or less range of motion between the slackest effective seat tube angle obtained when telescoping seat post assembly 260 is fully compressed, and the steepest effective seat tube angle obtained when telescoping seat post assembly 260 is fully extended. In certain embodiments, the range of rotational motion provided by aft pivot assembly 221 may be a function of the travel length (as used herein with respect to telescoping seat post assembly 260, the expression “travel” encompasses the difference in the length of telescoping seat post assembly between its fully compressed and fully extended positions).

Given the finite range of angular motion of aft pivot assembly 221, the present disclosure contemplates a wide range of pivot systems and structures by which lower portion 262 of telescoping seat post assembly 260 may be pivotably connected to aft pivot assembly 221. According to certain embodiments, aft pivot assembly 221 comprises a tube 265 with an interior diameter proportioned to accommodate the exterior diameter of lower portion 262 of telescoping seat post assembly 260 and a clamp for compressing the tube to retain lower portion 262 of telescoping seat post assembly 260. According to various embodiments, the exterior of tube 265 comprises a clevis bracket, clevis rod end, or hollow boss through which a clevis pin or axle about which lower portion 262 pivots.

In some embodiments, aft pivot assembly 221 comprises a clevis bracket attached to frame 200 at a location with a reach point R(ap) closer to the reach point of the bottom bracket (R(bb)) than the reach point of the first fore pivot assembly (R(f1)). While in the explanatory example of FIG. 2, R(ap) is shown as having a reach point closer to that of the rear axle (R(rx)) than the reach point of the bottom bracket shell (R(bb)), embodiments according to this disclosure, and include embodiments wherein R(ap) and R(bb) are the same, or where R(bb) is closer to R(rx) than R(ap) (i.e., where the reach point of aft pivot assembly 221 is in line with that of bottom bracket shell 215, or forward of the bottom bracket).

In various embodiments, aft pivot assembly comprises one or more bushings or bearings disposed on frame 200, through which an axle also passing through a hollow protrusion (for example, a hollow boss) on lower portion 262 passes. Referring to the explanatory example of FIG. 2, the bearings of aft pivot assembly 221 are mounted to the first and second top stays (271a and 271b) of top tube assembly 271. Further, in some embodiments, aft pivot assembly 221 may be connected to the first and second tubes 281a and 281b of a seat tube assembly 281.

In some embodiments, one or more components of lower portion 262, frame 200 and aft pivot assembly 221 may be made integral with one another. For example, in some embodiments, tube 265 and a separate clamp for lower portion 262 of telescoping seat post assembly 260 may be omitted, and a hollow boss or other hardware for pivotably connecting lower portion 262 to aft pivot assembly 221 may instead be mounted directly on lower portion 262. Similarly, in certain embodiments, instead of rotational connection points (for example, axles, and bushings or bearings) aft pivot assembly 221 connects lower portion 262 to frame 200 through a section of flexible material.

In various embodiments, aft pivot assembly 221 includes one or more adjustable stops (sometimes referred to in the art as “knock blocks”) configured to confine the range of angles over which lower portion 262 may pivot. Depending on the geometry and configuration of frame 200 (for example, in smaller, full-suspension frames, or long-travel full suspension frames), setting hard limits on the range of angular range of motion may prevent unwanted contact between lower portion 262 and other components of the bicycle, such as the rear tire, rear triangle, rear shock or linkage(s) between the rear shock and rear triangle.

FIG. 2 illustrates a non-limiting example of a frame architecture according to this disclosure. As noted elsewhere in this disclosure, modern fabrication and design techniques permit a wide variety of bicycle frame architectures beyond the traditional “double triangle” geometry associated with unsuspended or front-suspension only frames made from joined sections of tube. The embodiments described with reference to FIG. 2 are intended to be illustrative, rather than limitative of the scope of this disclosure.

Referring to the explanatory example of FIG. 2, frame 200 comprises a top tube assembly 271 comprising a first top stay 271a and a second top stay 271b. According to certain embodiments, first top stay 271a comprises a first section of material (for example, steel, titanium, carbon fiber or aluminum), connected at a first end to head tube 207 and at a second end to brake-side rear dropout 299a. In this explanatory example, second top stay 271b comprises a second section of material (for example, steel, titanium, carbon fiber or aluminum) connected at a first end to head tube 207, and at a second end to drive-side rear dropout 299b. In this example, top tube assembly 271 further comprises a first brace 273a and a second brace 273b connecting first top stay 271a and second top stay 271b.

As shown, for example, in FIG. 2B, first top stay 271a and second top stay 271b are disposed on opposite sides of fore-aft centerline 297, creating one or more open spaces (i.e., spaces without any tubing) in which fore-aft centerline 297 is exposed proximate to aft pivot assembly 221, providing space in which telescoping seat post assembly can pivot without contacting the top tube. While FIG. 2 describes embodiments wherein top tube assembly 271 comprises a symmetrical pair of top stays straddling telescoping seat post assembly 260, embodiments according to this disclosure are not so limited, and encompass embodiments comprising an asymmetric top tube assembly in which fore-aft centerline 297 is exposed proximate to aft pivot assembly 221. Additionally, or alternatively, in some embodiments according to this disclosure, top tube assembly 271 may comprise a section of material (for example, a tube) with a hole or fork exposing fore-aft centerline 297 proximate to fore-aft centerline 297. In some embodiments, frame 200 is a full-suspension frame, and top tube assembly 271 terminates near aft pivot assembly 221.

As shown in the illustrative example of FIG. 2, in some embodiments, frame 200 further comprises a seat tube assembly 281. As used in this disclosure, the expression “seat tube assembly” encompasses a structure linking bottom bracket shell 215 with a top tube assembly 271, and, as used in this disclosure, the expression “seat tube assembly” does not connote any requirement that a seat post can be inserted into seat tube assembly. As shown in FIG. 2, seat tube assembly 281 comprises a first tube 281a and a second tube 281b connecting bottom bracket shell 215 with top tube assembly 271. As shown in FIG. 2, first tube 281a and second tube 281b are disposed on opposing sides of fore aft centerline 297, thereby exposing fore-aft centerline 297 proximate to aft pivot assembly 221 and providing room for lower portion 262 of telescoping seat tube assembly 260 to pivot and swing.

Because telescoping seat post assembly 260 is pivotably connected to aft pivot assembly 221, the effective seat tube angle of frame 200 is not related to the angle of seat tube assembly 281, seat tube assembly 281 may be made steeper or brought forward relative to bottom bracket shell, thereby increasing the clearance between the rear wheel and seat tube assembly 281, relative to a “normal” frame, in which the seat post is disposed within a single seat tube. From a design standpoint, the additional clearance provided by certain embodiments according to this disclosure may be particularly advantageous—for example, in smaller-framed bicycles using 29″ tires, or long-travel full suspension bicycles in smaller frame sizes.

FIGS. 3A-3D (collectively, “FIG. 3”) illustrate aspects of the kinematics of an example frame and telescoping dropper post according to various embodiments of this disclosure. To avoid repetition and facilitate cross reference, elements common to FIGS. 2 and 3 are numbered similarly.

As noted elsewhere in this disclosure, in “normal” bicycle frames, where a telescoping seat post is retained in a backwards-tilting seat post or other structure maintained at a fixed angle relative to the head tube, the saddle moves backwards relative to the bottom bracket as the seat post extends upwards and forwards as the seat post compresses. From a biomechanical and performance standpoint, the above-described motion of the saddle in response to compression and extension of the telescoping seat post is undesirable for at least the following reasons. First, when the saddle is fully extended for climbing or sprinting, there is a higher likelihood of the rider having to pull on the handlebars to balance out a backward force from the cranks at the top of the pedal stroke, which diminishes pedaling efficiency and can produce knee pain. Second, because the rider moves forwards as the post descends, the rider's center of gravity is necessarily not centered over the bottom bracket shell for a substantial portion of the seat post's travel. For example, if the rider's center of gravity is correctly positioned over the bottom bracket when the seat post is fully compressed, then her center of gravity will be substantially behind the bottom bracket when the seat post is fully extended, resulting in awkwardly slow, or “floppy” handling and a higher incidence of the front wheel lifting under power. However, if the rider's center of gravity is correctly positioned over the bottom bracket at the top of the seat post's travel, the rider will be substantially forward of the center of gravity when the saddle is compressed, which may result in awkwardly fast, or “squirrely” handling and a higher incidence of the rider pitching over the handlebars during braking due to the weight imbalance.

Referring to the illustrative example of FIG. 3A, frame 200 is shown with telescoping seat post assembly 260 is a fully compressed position (shown in solid lines) and in a fully extended position (shown in dotted lines). As shown in the FIG. 3A, because the upper portion of telescoping seat post assembly 260 is pivotably connected to first fore pivot assembly 231 through tension bar 251, saddle 263 does not move linearly backwards in response to the extension of telescoping seat post assembly. Rather, extension of telescoping seat post assembly 260 causes telescoping seat post assembly 260 to pivot clockwise about aft pivot assembly 221 in response. As shown in FIG. 3A, the rotation of telescoping seat post assembly 260 as it extends has at least the following effects on the geometry of frame 200. First, the effective seat tube angle 301 when telescoping seat post assembly 260 is fully extended is greater (also referred to as “steeper”) than the effective seat tube angle 305 when telescoping seat post assembly 260 is fully compressed. In the illustrative example of FIG. 3A, the difference between seat tube is approximately 10 degrees, wherein the effective seat tube angle 301 is about 70 degrees, and effective seat tube angle 305 is about 69 degrees. Depending on the geometry and range of telescoping seat post assembly 260, the total difference in effective seat tube angle may be greater or smaller. In the example of FIG. 3A, saddle 263 occupies substantially the same reach point throughout the travel of telescoping seat post assembly 260. However, as discussed herein, in certain embodiments, the kinematics of the effective seat tube angle in response to actuation of the dropper may be tuned such that, saddle 263 occupies a more forward (i.e., closer to the reach point of the head tube) reach point when telescoping seat post assembly 260 is fully extended than when compressed.

FIGS. 3B-3D further illustrate aspects of the biomechanical advantages provided by certain embodiments according to this disclosure. Referring to the illustrative example of FIG. 3B, an example frame 200 according to various embodiments of this disclosure is shown built up as a complete bicycle, upon which a rider 351 is positioned in a seated pedaling position. In the example of FIG. 3B, rider 351's center of mass occupies a first location 355a, which is situated along a substantially vertical line relative to bottom bracket shell 215. Similarly, when telescoping seat post assembly 260 is fully extended, rider 351's knee 357 is situated along a substantially vertical line relative to pedal spindle 171. From a biomechanical standpoint, rider 351 is in an optimum position for seated cranking at high power. In other words, with telescoping seat post assembly 260, the effective seat tube angle of frame 200 substantially mimics the effective seat tube angle provided by a cross-country mountain bike or a road bike, thereby facilitating efficient power transfer through pedaling.

FIG. 3C illustrates aspects of the weight distribution of the bicycle comprising frame 200 and rider 351 when telescoping seat post assembly 260 is fully compressed. As shown in FIG. 3A, in certain embodiments according to this disclosure, compression of telescoping seat post assembly 260 causes the effective seat tube angle of frame 200 to decrease or slacken. By relaxing the effective seat tube angle of frame 200 in response to compressing telescoping seat tube assembly 260, the tendency of the saddle of a “normal” frame with a seat tube maintained at a consistent angle relative to the head tube to move forward as it moves down is arrested. As shown in the example of FIG. 3C, even when telescoping seat post assembly 260 is fully compressed, rider 351's center of mass occupies a second location 355b, which, like first location 355a, is vertically aligned with bottom bracket shell 215. In other words, in addition to ensuring correct knee position relative to the pedal spindle when telescoping seat post assembly 260 is at the top of its travel, certain embodiments according to this disclosure also rider 351's center of mass over bottom bracket shell 215 throughout the travel of the dropper post.

FIG. 3D illustrates a superposition of FIGS. 3B and 3C to further illustrate how, the change in effective seat tube angle across the travel of telescoping seat post assembly 260. As shown in FIG. 3D, the fore-aft difference between first location 355a and second location 355b is relatively minimal, and rider 351's center of mass remains centered over bottom bracket shell 215 throughout the travel of telescoping seat post assembly 260, thereby completely or substantially eliminating the issues of a rider being either too far back and/or too far forward at different saddle heights.

FIG. 4 illustrates a detailed partial cutaway view of an example of a first fore pivot assembly 231 according to various embodiments of this disclosure. Referring to the illustrative example of FIG. 4, in some embodiments, first fore pivot assembly 231 comprises a section of material (for example, steel, aluminum, titanium or carbon fiber) attached to a top tube assembly (for example, to upper portions of first top stay 271a and second top stay 271b (not shown in FIG. 4) proximate to head tube 207. According to various embodiments, an upper headset bearing 209a is pressed into a first end of head tube 207, and a lower headset bearing 209b is pressed into a second end of head tube 207.

According to various embodiments, first fore pivot assembly 231 comprises two or more vertical members (for example, vertical member 401) with one or more pairs of opposing through holes (for example, holes 451 and 453) which define one or more devises for retaining a clevis pin 403 passing through one or more through-holes of a clevis hook at second end 253 of tension bar 251. In some embodiments, by providing a plurality of pivot points at first fore pivot assembly 231, the kinematics of the change in effective seat tube angle as telescoping seat post assembly 260 may be fine-tuned by slightly changing the location at which second end 253 of tension bar 251 pivots. Alternatively, or additionally, tension bar 251 may telescope or have a threaded component which allows the length of tension bar 251 to be adjusted for fine tuning of the seat post kinematics. The example of FIG. 4 is intended to illustrate, rather than limit, embodiments according to the disclosure and other embodiments are possible, and within the contemplated scope of this disclosure. For example, in some embodiments, the clevis structure could be provided on tension bar 251 and a component with a through hole could be provided on the frame.

FIG. 5 illustrates an example of how in certain embodiments according to the present disclosure, moving the pivot point at which at which second end 253 of tension bar 251 connects to first fore pivot assembly 231 and/or changing the length of tension bar 251 effects the seat post kinematics.

Referring to the illustrative example of FIG. 5, a superposition showing the relative positions of tension bar 251 and telescoping seat post assembly in four configurations of frame 200 is provided in the figure. At first position 501, tension bar 251 is pivotably connected to first fore pivot assembly 231 at a pivot point (for example, hole 451 in FIG. 4) closest to upper bearing 209a of headset 209, and telescoping seat post assembly 260 is fully extended. At second position 503, tension bar 251 is pivotably connected to first fore pivot assembly 231 at a pivot point (for example, hole 453 in FIG. 4) aft of upper bearing 209a of headset 209. As shown in FIG. 5, using the more forward pivot point (for example, hole 451 in FIG. 4) results in a slightly steeper effective seat tube angle when telescoping seat post assembly 260 is fully extended.

At third position 551, tension bar 251 is pivotably connected to first fore pivot assembly 231 at the same pivot point as first position 501, only this time, telescoping seat post assembly 260 is fully compressed. Further, at fourth position 553, tension bar is pivotably connected to first fore pivot assembly 231 at the same pivot point as second position 503. As shown in FIG. 5, using the more forward pivot point (for example, hole 451 in FIG. 4) results in a slightly steeper effective seat tube angle when telescoping seat post assembly 260 is fully compressed. In this way, certain embodiments according to the present disclosure provide a level of micro-adjustment not present in conventional framesets in which the seat post is locked at a single angle relative to the head tube.

FIG. 6 illustrates a partial cutaway view of an example of an aft pivot assembly 221 according to various embodiments of this disclosure.

Referring to the non-limiting example of FIG. 6, in certain embodiments, aft pivot assembly 221 comprises a retaining tube 265, which is a hollow section of material (for example, steel, aluminum, carbon fiber or titanium) with an interior diameter sized to fit an exterior diameter of lower portion 262 of telescoping seat post assembly 260. In certain embodiments, retaining tube 265 may have an interior diameter proportioned to fit a seat post having a standard diameter (for example, 27.2, 30.9 or 31.6 mm). According to various embodiments, retaining tube 265 further comprises one or more clamps 601 which slightly compress retaining tube 265 to hold lower portion 262 of telescoping seat post assembly 260 in a fixed position relative to retaining tube 265. Further, in certain embodiments according to this disclosure, aft pivot assembly 221 further comprises an axle hanger 605 connected to retaining tube 265. The axle hanger comprises a section of material protruding from retaining tube 265 surrounding an axle 615, wherein axle 615 connects to a set of bushings or bearings at one or more fixed points on frame 200. Depending on embodiments, axle 615 may be integral to axle hanger 605 (akin to the axle on the hanger of a roller skate or skateboard truck) or may be removable.

As noted elsewhere in this disclosure, aft pivot assembly 221 comprises one, non-limiting example of an aft pivot assembly according to embodiments of this disclosure. Other embodiments of a structure permitting a telescoping seat post assembly 260 to pivot and resist the tendency of the effective seat tube angle of a frame during extension of a dropper seat post are possible and within the contemplated scope of this disclosure.

FIG. 7 illustrates, in detailed cutaway view, an example of a pivotable connection between a first end 252 of a tension bar 251 and an upper portion 261 of a telescoping seat post assembly, according to various to embodiments of this disclosure.

Referring to the explanatory example of FIG. 7, in this example, first end 252 comprises a clevis 701, and seat post 710 of upper portion 261 of the telescoping seat post has a boss 705 with a through hole. In this non-limiting example, first end 252 pivotably connects to upper portion 261 of the telescoping seat post assembly through a clevis pin passing through both clevis 701 and boss 705. In certain embodiments, first end 252 may be pivotably connected to a portion of seat clamp 715, or alternatively, to saddle rails 720.

The example of a pivotable connection between first end 252 and upper portion 261 of telescoping seat post assembly 260 is for illustration only, and other embodiments of a pivoting connection between tension bar 251 and upper portion 261 are within the contemplated scope of this disclosure. For example, in some embodiments, instead of a rotational pivot, a flexible section of material may connect tension bar 251 and upper portion 261.

FIGS. 8A and 8B illustrate two examples of frames according to various embodiments of this disclosure. For convenience of cross-reference, elements shown in FIGS. 8A and 8B common to other figures of this disclosure are numbered similarly.

While embodiments according to this disclosure have thus far been described with reference to examples comprising a single fore pivot assembly (for example, first fore pivot assembly 231 in FIG. 2A), the present disclosure is not so limited. Embodiments according to the present disclosure encompass embodiments wherein tension bar 251 is pivotably connected to frame the frame at multiple points. By employing multiple pivoting connection points, the kinematics of the change in effective seat tube angle can be made more or less progressive than with a single pivot point. As used in this disclosure, the expression “progressive” encompasses the rate of change of a parameter (for example, effective seat tube angle) changing at a greater rate per increment of travel of a telescoping seat post varying across the travel of the telescoping seat post.

Referring to the non-limiting example of FIG. 8A, a tension bar 251 is pivotably connected to frame 800 through a first fore pivot assembly 801 and a second fore pivot assembly 811. In this example, first fore pivot assembly 801 is situated at a reach point that is closer to the reach point of head tube 807 than second fore pivot assembly 811. In the examples of FIGS. 8A and 8b, both first fore pivot assembly 801 comprise a linkage bar (for example, first linkage bar 803a and second linkage bar 803b) pivotably connected at one end to frame 800, and at another end to tension bar 251.

In the example of FIG. 8A, first fore pivot assembly 801 is mounted on the downtube 812, while second fore pivot assembly 811 is mounted on top tube assembly 871. In the example of FIG. 8B, both first fore pivot assembly 801 and second fore pivot assembly 811 are mounted on top tube assembly 871.

By making the connection between tension bar 251 and frame 800 “double jointed” with multiple fore pivot assemblies, the instant center of rotation of tension bar 251 becomes dynamic and moves as telescoping seat post assembly 260 extends and contracts.

In the illustrative example of FIG. 8A, telescoping seat post assembly 260 is shown fully compressed, and the instant center of rotation of tension bar 251 is below top tube assembly 871. However, as telescoping seat post assembly 260 extends, first linkage bar 803a rotates counterclockwise (in the view shown in FIGS. 8A & 8B), and second linkage 803b rotates clockwise (again, in the perspective shown in FIGS. 8A and 8B).

In the illustrative example of FIG. 8B, telescoping seat post assembly 260 is shown fully compressed, and the instant center of rotation of tension bar 251 is below top tube assembly 871. As telescoping seat post assembly 260 extends, both first linkage bar 803a and second linkage 803b rotate clockwise (again, in the perspective shown in FIGS. 8A and 8B), causing the instant center of rotation of tension bar 251 to drop.

FIGS. 9A-9B illustrate aspects of the kinematics of certain embodiments according to this disclosure relative to the kinematics of a “regular” bicycle frame in which a telescoping seat post is retained at a fixed angle relative to the head tube.

Referring to the non-limiting example of FIG. 9A, the effective seat angle (expressed in degrees) of at different travel points of a long travel telescoping seat post assembly (for example, telescoping seat post assembly 260) are shown in the chart. First column 901 provides values of the effective seat tube angle as a function of seat post extension for a frame according to certain embodiments of this disclosure having a single fore pivot assembly (for example, frame 200 in FIG. 2A). Second column 903 provides values of the effective seat tube angle as a function of seat post extension for a first embodiment of a frame having two first fore pivot assemblies connected to the tension bar through linkages (for example, frame 800 in FIG. 8B). Third column 905 provides values of the effective seat tube angle as a function of seat post extension for a second embodiment of a frame having two first fore pivot assemblies connected to the tension bar through linkages (for example, frame 800 in FIG. 8A). Fourth column 907 provides values of the effective seat tube angle as a function of seat post extension for a “regular” frame, in which the telescoping seat post is maintained at a fixed angle relative to the head tube.