Patent Publication Number: US-2022213625-A1

Title: Upper for an article of footwear with a cuff

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application, having attorney docket number 384046/160058US04CON and entitled “AN UPPER FOR AN ARTICLE OF FOOTWEAR WITH A CUFF,” is a continuation application of co-pending U.S. application Ser. No. 16/380,278, filed Apr. 10, 2019, and entitled “AN UPPER FOR AN ARTICLE OF FOOTWEAR WITH A CUFF,” which is a divisional application of U.S. application Ser. No. 15/454,034, filed Mar. 9, 2017, and entitled “AN UPPER FOR AN ARTICLE OF FOOTWEAR WITH A CUFF,” which claims the benefit of priority of U.S. Provisional Application No. 62/307,115, filed Mar. 11, 2016, and entitled “AN UPPER FOR AN ARTICLE OF FOOTWEAR WITH A CUFF.” U.S. application Ser. Nos. 16/380,278 and 15/454,034 and U.S. Provisional Application No. 62/307,115 are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     A conventional article of footwear generally includes two primary elements: an upper and a sole structure. The upper is secured to the sole structure and forms a void within the article of footwear for comfortably and securely receiving a foot. The sole structure is secured to a lower surface of the upper so as to be positioned between the upper and the ground. In some articles of athletic footwear, for example, the sole structure may include a midsole and an outsole. The midsole may be formed from a polymer foam material that attenuates ground reaction forces to lessen stresses upon the foot and leg during walking, running, and other ambulatory activities. The outsole is secured to a lower surface of the midsole and forms a ground-engaging portion of the sole structure that is formed from a wear-resistant material. 
     The upper of the article of footwear generally extends over the instep and toe regions of the foot, along the medial and lateral sides of the foot, and around the heel region of the foot. Access to the void on the interior of the upper is generally provided by an ankle opening in a heel region of the article of footwear. A lacing system is often incorporated into the upper to adjust the fit of the upper, thereby facilitating entry and removal of the foot from the void within the upper. In addition, the upper may include a tongue that extends under the lacing system to enhance adjustability of the article of footwear, and the upper may incorporate a heel counter to limit movement of the heel. 
     BRIEF DESCRIPTION 
     In one aspect, an upper for an article of footwear may include a knit element, a collar area configured to form an ankle opening, and a cuff in the collar area. The cuff may be at least partially formed by the knit element and may include a ribbed knit structure of the knit element. 
     The knit element may include a second knit structure, where a lower portion of the upper is formed of the second knit structure. 
     The ribbed knit structure may include at least one rib with a length extending along a longitudinal direction of the cuff. 
     The ribbed knit structure may include a yarn formed of an elastic material. 
     The cuff may include at least one opening, and the opening may be formed on a knitting machine by skipping a series of consecutive needles on a needle bed occupying a distance at least three times as large as an unstretched width of the opening. 
     The cuff may include at least one yarn that is substantially hidden from view from a viewpoint directed at an outer surface of the cuff when the cuff is in an unstretched state. The at least one yarn may be revealed at the viewpoint when the cuff is in a stretched state. 
     The cuff may be configured to form an inverted state where an end portion of the cuff is inverted to form an overlapping portion. 
     The knit element may include at least one inlaid strand in a toe region of the upper. 
     In another aspect, an upper for an article of footwear may include a knit element with a first area, the first area including a first side and a second side opposite the first side. The first side may be formed of at least 30% more material than the second side such that the first area is configured to curve convexly away from the first side. 
     The first side may be formed of at least 50% more material than the second side. 
     The first area may be at least partially located in a toe region of the upper. 
     The first side may include a plurality of loops forming an outer surface of the upper. 
     The knit element may include a second area having a different knit structure than the first area. The second area may include a cuff located in a collar area of the upper. 
     The first area of the knit element may be formed on a knitting machine with a first series of needles on a first needle bed and a second series of needles on a second needle bed. 
     The first area may include at least one yarn that forms a loop around each needle of the first series of needles during a pass when forming the first area. The at least one yarn may be tucked at least at one needle of the second series of needles during the pass. 
     The at least one yarn may be tucked at every other needle of the second series of needles during the pass. 
     In another aspect, a method of manufacturing an upper for an article of footwear may include knitting a first pass of a knit element with a knitting machine, the knitting machine having a first series of needles on a first needle bed and a second series of needles on a second needle bed, where knitting the first pass includes. The method may also include forming a loop with at least one yarn on each of the needles of the first series of needles and tucking the at least one yarn at least at one of the needles of the second series of needles. 
     The step of tucking the at least one yarn to at least one of the needles of the second series of needles during the first pass may include tucking the at least one yarn to every other needle of the second series of needles. 
     The method may further include knitting a second pass of the knit element with the knitting machine, where knitting the second pass includes forming a loop with the at least one yarn on each of the needles of the first series of needles, and where knitting the second pass includes tucking the at least one yarn at the needles of the second series of needles that are unoccupied during the first pass. 
     The method may further include knitting a third pass of the knit element with the knitting machine, where the third pass includes forming a loop on each of the needles of the first series of needles and skipping all of the needles of the second series of needles. The method may further include knitting a fourth pass of the knit element with the knitting machine, where the fourth pass includes forming a loop on each of the needles of the second series of needles and skipping all of the needles of the first series of needles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an article of footwear in accordance with certain aspects of this disclosure; 
         FIG. 2  shows a medial-side view of an article of footwear including a cuff; 
         FIG. 3  illustrates a sequence for knitting a first knit structure; 
         FIG. 4  shows a medial-side view of an article of footwear including a cuff, where the cuff is in an inverted state; 
         FIG. 5  illustrates of a sequence for knitting a second knit structure; and 
         FIG. 6  shows an upper formed of a knit element having a curved portion in a toe region. 
     
    
    
     DETAILED DESCRIPTION 
     Various aspects are described below with reference to the drawings in which like elements generally are identified by like numerals. The relationship and functioning of the various elements of the aspects may better be understood by reference to the following detailed description. However, aspects are not limited to those illustrated in the drawings or explicitly described below. It also should be understood that the drawings are not necessarily to scale, and in certain instances details may have been omitted that are not necessary for an understanding of aspects disclosed herein, such as conventional fabrication and assembly. 
     Certain aspects of the present disclosure relate to uppers configured for use in an article of footwear. The uppers may be used in connection with any type of footwear. Illustrative, non-limiting examples of articles of footwear include a basketball shoe, a biking shoe, a cross-training shoe, a global football (soccer) shoe, an American football shoe, a bowling shoe, a golf shoe, a hiking shoe, a ski or snowboarding boot, a tennis shoe, a running shoe, and a walking shoe. The uppers may also be incorporated into non-athletic shoes, such as dress shoes, loafers, and sandals. 
     With respect to  FIG. 1 , an article of footwear is generally depicted as comprising a sole  110  and an upper  120 . The upper  120  includes a lateral side  104 , a medial side  105 , and a heel region  122 . The area of the shoe where the sole  110  joins the outer edge of the upper  120  may be referred to as the biteline  116 . The upper  120  may be joined to the sole  110  in a fixed manner using any suitable technique, such as through the use of an adhesive, by sewing, etc. 
     In some embodiments, the sole  110  includes a midsole  111  and an outsole  112 . The article of footwear may additionally comprise a throat  107  and an ankle opening  121 , which is surrounded by a collar  129  and leads to a void  128 . The upper  120  defines the void  128  of the article of footwear that accommodates a foot of a person. The throat  107  is disposed in a mid-foot region  102  of the upper  120 . The mid-foot region  102  is generally a section of the upper  120  located between the heel region  122  and a toe portion  101 . 
     In  FIG. 1 , a tongue  124  is disposed in the throat  107  of the article of footwear but the tongue  124  is an optional component, as is the lace  103 . Although the tongue  124  depicted in  FIG. 1  is a traditional tongue, the tongue  124 , if included, may be any type of tongue, such as a gusseted tongue or a burrito tongue. If a tongue is not included, the lateral and medial sides of the throat  107  may be joined together, for example. 
     The upper  120  may be formed at least partially of a knit element  140  (and, as depicted, the upper  120  may be substantially or entirely formed of the knit element  140 ). While the upper  120  is herein described as including the knit element  140 , it alternatively or additionally could include a textile component formed by a process other than knitting (e.g., weaving). The knit element  140  may be a multi-layer knit element such as a two-layer knit element with a first layer forming a first side and a second layer forming a second side. The first side may define the outer surface of the upper  120  and the second side may define a surface facing the void  128  of the article of footwear. 
     Referring to  FIG. 2 , an upper  220  of the article of footwear may have a collar area  229  that leads to a void (not shown). The collar area  229  may be formed of a knit element  240 . In some embodiments, the collar area  229  may include a cuff  230 . The cuff  230  may be configured to surround an ankle and/or at least a portion of a leg of a person wearing the article of footwear. In some embodiments, the cuff  230  may extend about 8 inches or more above an ankle of the person wearing the article of footwear, although the height of the cuff  230  may be adjusted based on the size of the article of footwear, the type of article of footwear (e.g., the type of shoe, such as a walking shoe or basketball shoe), the preference of the person wearing the article of footwear, or the like. The cuff  230  may be advantageous, for example, by providing additional support to the ankle and/or lower leg (e.g., to prevent or reduce ankle inversion), by providing protection from harsh conditions (e.g., when the article of footwear is a boot for rugged outdoor use), by providing a foot with a comfortable and secure fit, and/or by providing desirable aesthetics. 
     The knit element  240  may include more than one type of knit structure, such as a ribbed knit structure, a single or double jersey knit structure, or the like. For example, as depicted, the knit element  240  may have a first portion  232  (which may include the cuff  230 ) that is formed of a first knit structure and a second portion  234  that is formed of a second knit structure. While the knit element  240  is described as having two knit structures, it is contemplated that more than two knit structures may be included. The first portion  232  and the second portion  234  may be knitted integrally on a knitting machine such that they do not need to be attached to one another in a post-knitting process. Further, each knit structure may vary in certain aspects at different locations (e.g., certain characteristics of the first knit structure may vary at different locations of the first portion  232 ). 
     In some embodiments, the first portion  232  may be formed of a ribbed knit structure (e.g., a full rib, a full cardigan, a 1×1 rib, a 2×1 rib, a Fisherman&#39;s rib, or an English rib), while the second portion  234  may be formed of a second knit structure that is not a ribbed knit structure (e.g., a single jersey or double jersey structure). As shown in the depicted embodiment, the first portion  232  of the knit element  240  may extend from an end portion  238  of the cuff  230  to the second portion  234  and through the throat  207  of the upper  220 . The second portion  234  may extend adjacent to the biteline  216  substantially around the article of footwear from the heel region  222  on the medial side, around the toe region  201 , and to the heel region  222  on the lateral side (not shown). Although not shown in  FIG. 2 , the knit element  240  may include a transition zone between the first portion  232  and the second portion  234  where the first knit structure of the first portion  232  transitions into the second knit structure of the second portion  234  over a distance. 
     The first portion  232  and the second portion  234  may have a common yarn. In some embodiments, at least one of the yarns forming the first portion  232  may be different than at least one of the yarns forming the second portion  234 . For example, the first portion  232  may be at least partially formed with yarns that have an elastic material. It will be understood that the term “elastic material” as used herein shall refer to material that is more elastic than inelastic materials (inelastic materials including thermoplastic polymers, leather, synthetic leather, vinyl, or the like). Exemplary elastic materials suitable for use in the disclosed embodiments may include latex, spandex, or elastane (which are often referred to as Lycra). A fiber of elastic material (e.g., a fiber of spandex) may be stretched to twice its unstretched length, 4 times its unstretched length, or even 8 times or more its unstretched length without breaking. A yarn that is substantially made of an elastic material may be referred to herein as an “elastic yarn.” These elastic yarns of the first portion  232  may be combined with yarns made of inelastic or other materials. On the other hand, the second portion  234  may be substantially free of elastic yarns. In some embodiments, the second portion  234  may be formed primarily of polyester yarns, although other suitable yarns may additionally or alternatively be used. 
     In some embodiments, the cuff  230  may be formed of a knit structure that exhibits a high degree of elasticity, such as a ribbed knit structure (e.g., a full cardigan knit structure or an English ribbed knit structure). Because a ribbed knit structure is particularly elastic in a direction perpendicular the length of its ribs, it may be advantageous to provide a cuff  230  with a ribbed knit structure having one or more ribs  231  extending along the longitudinal axis of the cuff  230 , which may allow the cuff  230  to snugly wrap around an ankle and/or leg of a person. One particular example of a process for forming a ribbed knit structure suitable for use in the cuff  230  is illustrated by a sequential knit diagram in  FIG. 3 . 
     Referring to  FIG. 3 , step  3 A illustrates a pass (e.g., a yarn traveling past and/or through the needles of a knitting machine) in the left direction where a first yarn  366  forms a loop at each needle on the front needle bed  362  and is tucked at each needle on the back needle bed  360 . The first yarn  366  may be a single yarn or may be a plurality of yarns or other strands. Note that the directions (left and right) and/or the needle beds (front and back) could be reversed. In step  3 B, a second yarn  368  passes in the left direction where it forms a loop at each needle on the back needle bed  360  and is tucked at each needle on the front needle bed  362 . The second yarn  368  may have different characteristics (e.g., elasticity, strength, denier, color) than the first yarn  366 . In some embodiments, one of the first yarn  366  and the second yarn  368  is an elastic yarn, while the other is a polyester yarn. In another embodiment, they are both elastic yarns but have different colors. Next, in Step  3 C, the first yarn  366 , now passing to the right, forms a loop at each needle on the front needle bed  362  and is tucked at each needle on the back needle bed  360 . Note that a different yarn (e.g., the second yarn  368  or a third yarn) may be utilized during this step. Finally, in the depicted step  3 D, the second yarn  368 , passing to the right, forms a loop at each needle of the back needle bed  360  and is tucked at each needle of the front needle bed  362 . It is noted that this sequence may use any suitable number of yarns, and is not limited to just two. Each of the yarns may be selected with particular properties to thereby optimize the characteristics of the cuff  230 . 
     The described sequence in  FIG. 3  may be advantageous as it may form a stable structure that is elastic particularly in the horizontal direction when referring to  FIG. 2  and  FIG. 3A . This elasticity may correspond with a comfortable and secure fit around the ankle, foot, and/or leg of a wearer. The elastic effect may be amplified by utilizing one or more elastic yarns. In one non-limiting example, at least 20% of the yarns forming the cuff  230  are yarns formed at least partially of an elastic material, and in some embodiments about 50% or more (up to even 100%) of the yarns forming the cuff  230  are at least partially formed of an elastic material. For example, referring to  FIG. 3 , the first yarn  366  and/or the second yarn  368  may be formed of spandex. Further, the stability of the knit structure formed by this sequence in combination with spandex yarns may provide a cuff  230  that is sufficiently stable such that it does not substantially sag, bend, or otherwise deform under its own weight when the article of footwear is not in use. This structure may allow a cuff  230  being 6 inches tall, 12 inches tall, or 16 inches tall (or even taller) to stand without additional support. In exemplary embodiments, the cuff  230  may be about 8 inches tall. 
     In some embodiments, referring back to  FIG. 2 , the ribbed knit structure forming the cuff  230  may exhibit desirable aesthetic properties. For example, the first yarn  366  and the second yarn  368  described in  FIG. 3  may have different colors that produce a desirable visual contrast. The knit structure formed by the sequence of  FIG. 3 , for example, may have two opposite sides, where one side appears to be the inverse of the other side. In some embodiments, the cuff  230  may have a dynamic visual effect when the article of footwear is in use. For example, some yarns (e.g., the second yarn  368  of  FIG. 3 ) may be partially or substantially hidden from view from at least one viewpoint directed at the outer surface of the cuff  230  when the cuff  230  is in an unstretched state. The unstretched state may refer to a state where the article of footwear is not being worn such that the cuff  230  stands free, and/or it may refer to a state where the article of footwear is being worn but the cuff  230  is stretched to some degree less than its maximum functional amount of stretch. When the cuff  230  is then stretched beyond the unstretched state such that it shifts to a stretched state, the hidden yarns may be revealed into view from the above-mentioned viewpoint. This stretching may be the result of a person putting on the article of footwear and/or moving an ankle such that the cuff  230  is distorted. As a result, certain colors may alternate between being viewable and not being viewable as a wearer walks, run, etc. This may produce a desirable visual effect to the person wearing the article of footwear and/or an onlooker. 
     As shown in  FIG. 2 , one or more openings (depicted as the openings  236 ) may be formed in the cuff  230  or at another location of the knit element  240 , including in areas of the knit element  240  where an elastic yarn is located. The openings may have any size, and in some embodiments may have an unstretched width from about ⅛ of an inch to about 1 inch, although it is contemplated that larger or smaller openings may be used. Any suitable number of openings may be provided. Exemplary embodiments may have anywhere from about 1 opening to about 100 openings associated with each ankle of a person, although more openings may be provided. The openings  236  may be advantageous for increasing the breathability, flexibility, and aesthetic characteristics of the article of footwear, which may be desirable particularly in athletic shoes used in circumstances where athletic performance is important. 
     To form an opening  236 , any suitable knitting technique or other technique can be used. The openings  236  may be cut from the knit element  240  after the knit element  240  is formed. In one embodiment, the openings  236  may be formed in the knit element  240  by skipping a series of needles on one or more needle beds during a knitting process. Herein, “a series of needles” refers to two or more consecutive needles on a single needle bed of a knitting machine. The number of needles skipped during each pass may have a particular sequence (e.g., two needles are skipped during two passes, four needles are skipped during the next two passes, and then six needles are skipped during the subsequent two passes) such that the formed opening has a pyramid shape, a diamond shape, or the like. In some embodiments, each opening  236  may be formed by skipping a series of needles that occupies a distance substantially greater than an unstretched width of the opening  236  itself. To illustrate, the opening  236  may be formed with a relatively large width when on the knitting machine (e.g., when yarns surrounding the opening  236  are stretched), but the width of the opening  236  may be smaller when removed from the knitting machine and when the opening  236  is in a relaxed, unstretched state. In one example, an opening  236  may correspond to skipping a series of six consecutive needles on a standard-sized needle bed. That series of six needles may occupy a distance equal to about 2 times, 4 times, or 8 times (or more) the width of each of the plurality of openings  236  in an unstretched state when incorporated into the article of footwear. In an exemplary embodiment, the skipped series of needles occupies a distance equal to about 3 times the unstretched width of the openings  236 . 
     Referring to  FIG. 4 , the cuff  230  is shown in an inverted state (as opposed to an upright state shown in  FIG. 2 ), where an overlapping portion  242  of the cuff  230  overlaps another portion of the cuff  230 . Accordingly, the cuff  230  may be configured such that at least an end portion  238  of the cuff  230  can be folded over or inverted to overlap another portion of the cuff  230  to thereby form the inverted state. As depicted, the end portion  238  of the cuff  230  may be pulled down over (or alternatively under) the outer surface of the cuff  230  and may block the view of at least a portion of the outer surface. It is contemplated that in some embodiments, the overlapping portion  242  is permanent (e.g., by sewing or otherwise adhering the end portion  238  in its location as depicted in  FIG. 4 ), although in exemplary embodiments, the cuff  230  may be configured such that a person can switch back and forth between the upright state of  FIG. 2  and the inverted state of  FIG. 4  while wearing the article of footwear and/or prior to putting the article of footwear on. The ability to convert from the upright state to the inverted state (and vice versa) is advantageous because the two states may be particularly suited for different functions. For example, the upright state may be particularly suited for the support and protection of an upper ankle and lower leg, while the inverted state may be particularly beneficial for comfort during casual activities, for a high degree of low-ankle support, and for facilitating the receipt and removal of a foot of the person when putting on and taking off the article of footwear. Further, it is contemplated that a removable protective device (e.g., a shin guard) or another object may be placed and held between the outer and inner layers of the overlapping portion  242 . The inverted state depicted in  FIG. 4  may also exhibit advantageous aesthetic properties. For example, because (as described above) the ribbed knit structure forming the cuff  230  may have different visual properties on each side (and potentially inverse visual properties), the overlapping portion  242  may produce a desirable visual contrast with the other portions of the knit element  240 . 
     As mentioned above, a ribbed knit structure is not limited to the cuff  230 , but may also occupy any other areas of the knit element  240 . As shown in  FIG. 4 , the ribbed knit structure extends within the knit element  240  into the throat  207  of the upper  220 , although this is not necessary. It is contemplated that the ribbed knit structure may occupy substantially all of the upper  220 , but in exemplary embodiments, a less elastic knit structure may be used to form the second portion  234  of the upper. 
     The throat area  244 , which is adjacent to the throat  207 , may include one or more loops  246  extending from the depicted tensile strands  248 . The tensile strands  248  are an optional component, and may form lace apertures (e.g., the aperture through the loops  246 ) to receive a lace and/or may surround other lace apertures formed in the knit element  240 . A tensile strand may be a yarn, a cable, a rope, or any other type of strand. A tensile strand may be flexible, but it also may have a substantially fixed length measured from a first end to a second end. As such, the tensile strand can be substantially inelastic. The one or more tensile strands may extend across the upper  220  in any direction. The tensile strands can be at least partially inlaid within the knit element  240 . The tensile strands may limit the stretch of the knit element. Also, in some aspects, portions of the tensile strands may be exposed from the knit element. For example, portions of the tensile strands may extend out of the knit element in the throat region to form the loops  246 . See, for example, U.S. Patent Application Publication No. 2015/0359290, U.S. Patent Application Publication No. 2014/0237861, and U.S. Pat. No. 9,145,629, which are incorporated into the present application in their entirety. 
     Some tensile strands  256  may extend in the toe region  201  of the knit element  240  as shown in  FIGS. 2 and 4 . The tensile strands  256  may be at least partially inlaid in the knit element  240 , and in some embodiments they may be embedded and not visible on an outer surface of the upper  220 . The tensile strands  256  may extend from the biteline  216  on a medial side to the biteline  216  on a lateral side (not shown) in the toe region  201 . Advantageously, the tensile strands  256  may limit the elongation of the toe region  201  of the knit element  240 , particularly in the lateral direction 
     Any suitable knit structure may be used in the second portion  234 . One exemplary knit structure that may be used may be formed by using a knitting sequence performed on a knitting machine as illustrated in  FIG. 5 , which may involve only a single yarn (depicted as the yarn  570 ), although multiple yarns could be used. Two or more of the steps  5 A- 5 H may involve a single yarn or multiple yarns with different characteristics. Some of the yarns, and potentially all of the yarns used in this sequence, may include a polyester material. Further, more than one yarn may be involved at each step of the sequence, and each yarn may be selected with certain properties to optimize the characteristics of the second portion  234  of the knit element  240 . 
     In  FIG. 5 , the depicted series of needles on the front needle bed  562  may be associated with the outer side (referred to as the first side) of the knit element  240  (shown in  FIGS. 2 and 4 ), and the depicted series of needles on the back needle bed  560  may be associated with an inner side (referred to as the second side) of the knit element  240 , although the opposite is also possible. It is also contemplated that the directions of the passes described herein may be reversed. Step  5 A represents a pass in the left direction, where a tuck is performed at every other needle on the front needle bed  562  and at every other needle on the back needle bed  560  (note that the unoccupied needles are not shown in  FIG. 5 ). In some embodiments, a tuck at 1 out of 3 needles, 2 out of 3 needles, or another fraction of needles could be used during this step instead. In step  5 B, now passing to the right, a loop is formed on each of the needles of the front needle bed  562  and a tuck is performed at every other needle of the back needle bed  560 . As shown in step  5 B, the tucks during this pass may be performed on every opposite needle with respect to the tucks of the pass represented by step  5 A. The loops formed on the front needle bed  562  in step  5 B may form a portion of the outer surface of the knit element  240  (of  FIGS. 2 and 4 ). Step  5 C, now passing again to the left, involves a loop on every needle of the front needle bed  562 , and step  5 D, passing to the right, involves a loop on every needle of the back needle bed  560 . 
     The sequence of steps  5 A- 5 D may then be repeated as necessary. In some embodiments, the sequence of  FIGS. 5A-5D  is repeated but is offset by one needle (as depicted by steps  5 E- 5 H). For example, as shown by step  5 E, when passing to the left, a tuck may be performed on every other needle of the front needle bed  562  and every other needle of the back needle bed  560 , but these tucks may occupy the needles unoccupied during the pass of step  5 A. Then, as shown in step  5 F, a loop may be formed on each needle of the front needle bed  562  while a tuck is performed on every other needle of the back needle bed  560 , where the needles involved with the tucks on the back needle bed  560  are offset by one with respect to the tucks of step  5 B. In steps  5 G- 5 H, loops may be formed on each needle of the front needle bed  562  and each needle of the back needle bed  560 , respectively. While the sequence of  FIG. 5  is described herein in detail, it is contemplated that any one of the steps could be modified at one or more of the needles. Further, this sequence is not intended to be limiting, but is provided as an example of a sequence that may form a suitable knit structure for the second portion  234  ( FIGS. 2 and 4 ) of the knit element  240 . 
     One feature of a knit structure formed by the sequence of  FIG. 5  is that substantially more material is associated with one side of the knit element  240  than the other side (as measured by the surface area of yarns associated with each side). Similarly, one side may have substantially more loops than the other side. To illustrate, referring to the loops formed in the sequence illustrated by  FIG. 5  (i.e.,  8  passes performed over a series of 8 needles on the front needle bed  562  and a corresponding series of 8 needles on the back needle bed  560 ), 32 loops are formed on the front needle bed  562  while only 16 loops are formed on the back needle bed  560 . Accordingly, substantially more material and substantially more loops may form the outer side (the first side) of the knit element  240  than the opposite side (the second side) of the knit element  240 . In some embodiments, about 10%, 20%, 30%, 40%, 50%, 60%, or even 70% or more material and/or more loops may be associated with one side of the knit element  240  than the other. As a result of additional material and additional loops on the first side of the knit element  240 , the first side of the knit element  240  may be relatively compressed (when compared to the second side), and/or the second side of the knit element  240  may be relatively tensioned (when compared to the first side). This may provide the knit element  240  with a tendency to form and retain a curved shape (as shown in  FIG. 6 ). The tendency may be to curve convexly away from the first side (e.g., the outer side) of the knit element  240  as shown by curved portion  650  of  FIG. 6 . 
       FIG. 6  shows an upper  620  including a knit element  640  as it may appear after being formed on a knitting machine and prior to being shaped into its final form (and potentially before it is attached to other elements of the article of footwear, such as the sole  110  of  FIG. 1 ). The upper  620  is depicted with stripes extending laterally across the upper  620  on the outer surface for purposes of illustrating the curvature in  FIG. 6 , but these stripes are not required. In this embodiment, the upper  620  is shown without a cuff, although a cuff may also be included. Further, in this embodiment, the knit element  640  does not extend into the throat  607 . As shown, the knit element  640  may include a curved portion  650  in the toe region  601  of the upper  620 . The curved portion  650  may be formed due to the natural tendency of the knit element  640  to curve in that area, for example due to more material and/or more loops forming one side than the other. In some embodiments, the curved portion  650  may be formed at a different location of the knit element  640 . Multiple curved portions may be formed. 
     The ends  652  and  654  located in the heel region  622  of the upper  620  may be attached together (e.g., by sewing or with the use of an adhesive) to thereby form a seam in the heel region  622 . This seam may, in some embodiments, extend upward to the collar and/or through a cuff. A seam may additionally or alternatively be located anywhere else on the knit element  640 . In some embodiments (not shown), a seam may occur in the toe region  601  and may run through the curved portion  650 , which may be advantageous when using a particular knitting machine that is limited in the amount of curvature it can provide to one integrally-knit piece of a knit element. To overcome this limitation, the knitting machine may knit two pieces of a knit element separately, both exhibiting a tendency to curve. The pieces may then be attached (by, for example, sewing) such that the sum of the curvature of the two pieces is suitable for use in an upper. In other embodiments, a knit element may be integrally knit in one piece and may be seamless at least in its toe region. 
     After the knitting process, the upper  620  may go through one or more post-processing steps. For example, in no particular order, the upper  620  may be attached to other elements of the article of footwear (e.g., a strobel and/or a sole), may be placed over a foot-shaped last, and may be steamed or otherwise treated to be formed into its shape for incorporation into a final product (i.e., the article of footwear). The tendency to curve, as described above, may be advantageous for facilitating the shaping of the upper  620  into its desired shape (and the retention of this desired shape) with a reduced necessity for post-processing steps. Further, the upper may form and retain its final shape without including heat-activated and/or fusible yarns such as thermoplastic polymer yarns, which have been included in a knitted upper for their ability to form and retain a certain shape of the upper when heat-activated (e.g., melted and then cooled). 
     In  FIG. 6  the knit element  640  is depicted as clearly displaying curvature in the curved portion  650 , but it is also contemplated that this curvature may not be visually apparent when the knit element  640  is removed from a knitting machine and/or is lying flat when still separate of other components of the article of footwear. However, because the knit element  640  may have more material on its first side (e.g., outer side) than its second side (e.g., inner side), the curvature may be relatively easy to achieve and may be retained if and when the upper  620  goes through post-processing steps. Further, the tendency to curve may be amplified through certain post-processing steps such as steaming, which may, for example, tighten the yarns of the knit element  640 , which may increase the effect of a disparity between the amounts of material forming each side of the knit element  640 . 
     A knit structure formed by the sequence described in  FIG. 5  may also have other characteristics. For example, the knit structure of the second portion  234  (of  FIG. 4 ) may be relatively inelastic at least when compared to the first knit structure forming the first portion  232 . The second portion  234  may therefore provide structural integrity suitable for portions of the upper  220  that may particularly require strength and support and may repeatedly experience high stress. Further, the loops exposed on the outer surface of the knit element  240  (e.g., the loops formed on the front needle bed  562  of  FIG. 5 ) may form a textured surface of the knit element  240  that produce a desirable visual effect on the outer surface of the upper  220 . It is contemplated that these loops may be formed of multiple yarns with a variety of colors. Each color may be specifically located to thereby form an aesthetically pleasing pattern. Further, these loops exposed on the outer surface of the knit element  240  may provide the upper  220  with desirable functional characteristics (e.g., increased friction when gripping or contacting another object, such as a ball). 
     All of the structures and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While this invention may be embodied in many different forms, there are described in detail herein specific aspects of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular aspects illustrated. In addition, unless expressly stated to the contrary, use of the term “a” is intended to include “at least one” or “one or more.” For example, “a yarn” is intended to include “at least one yarn” or “one or more yarns.” 
     Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges (including all fractional and whole values) subsumed therein. 
     Furthermore, the invention encompasses any and all possible combinations of some or all of the various aspects described herein. It should also be understood that various changes and modifications to the aspects described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.