Stabilizer training wheel for bicycle

This invention is a side wheel attachment for removably attaching an auxiliary side wheel to a bicycle. The side wheel attachment comprises a single structural rod which is folded in the desired shape, i.e. forms a helical torsion spring. In natural unbiased condition, the first and second ends of the spring rod extend generally perpendicularly to one another. The first end of the spring is inversely U-shaped and tangentially engages by its web the rear axle of the bicycle where it can be fixed after adjusting its vertical position relative to the bicycle. The second end of the spring rod is rotatably engaged by the auxiliary side wheel, therefore acting as its axle. Both ends can angularly move relative to one another due to the helical spring. Therefore, in use, both auxiliary side wheels (installed on one side and the other of the rear bicycle wheel) and the rear bicycle wheel loaded by a bicycle rider, always stay in contact with the ground so as to accomplish their respective tasks. The novelty of this invention resides in the structural simplicity of the side wheel attachment which is, as previously stated, constructed from a single structural rod.

FIELD OF THE INVENTION 
The present invention relates to attachments for a bicycle, and more 
particularly to a training wheel assembly or an auxiliary side wheel 
assembly that controls dynamic lateral instability over uneven terrain. 
BACKGROUND OF THE INVENTION 
It is known in the art to provide a pair of auxiliary side wheels that are 
to be removably attached to the rear axle of a bicycle to control dynamic 
lateral instability of the bicycle. Indeed, bicycles are vehicles whose 
ground stability is dynamically enhanced by increased vehicle speed; at 
low vehicle speeds, lateral stability is difficult to maintain, 
particularly for children and other persons unskilled in the art of 
bicycle handling. These side wheels are most desirable when dealing with 
children who are learning the rudiments of riding a bicycle and who still 
have precarious stability when riding their bicycle. 
Many auxiliary side wheels that exist have the problem of comprising rigid 
attachment means for attaching them to a conventional bicycle. Such rigid 
attachment means are disadvantageous because the unevenness of the ground 
will often result in one of the side wheels being raised above the ground 
level exclusively of the laterally opposite other side wheel and therefore 
not stabilizing the bicycle as it is supposed to; on the other hand, the 
rear bicycle wheel could be raised above ground level, the rider then 
temporarily losing propulsion. Furthermore, when the bicycle and its rider 
enter into a turn, stability of the vehicle will again be compromised, 
since the bicycle will not be able to incline itself because of the side 
wheels' rigid attachment. 
A few patents have resolved this problem by including suspension means 
between the bicycle and the auxiliary wheels. 
U.S. Pat. No. 5,492,354 issued in 1996 to RAINEY discloses training wheels 
mounted at the end of a coil spring mounted on each side of the rear 
bicycle wheel axle. The coil springs have their axes in-line with respect 
to each other and offset below and parallel to the rear wheel axle. 
Inasmuch as the coil spring permits upward movement, the training wheels 
can be pulled backward against the action of the spring. A drawback of the 
apparatus disclosed by RAINEY is that friction resulting from uneven 
terrain may cause one wheel to be pulled backwards and thus resist forward 
movement causing the bicycle to turn. 
U.S. Pat. No. 2,450,979 issued in 1948 to MOLLER shows a coil spring 
suspension system for fitting to an auxiliary wheel assembly on a bicycle 
rear wheel axle. The auxiliary wheel axle is kept downwardly offset from 
the bicycle gearwheel axle by an L-shaped bracket interconnecting both 
axles. The hub of the auxiliary wheel is movably interconnected to the 
bicycle rear axle by an upwardly inwardly inclined, adjustable length coil 
spring member. Because of the relative angular values between the 
elongated coil spring member and the two wheel axles, lateral tilt play of 
the auxiliary wheel axle relative to the bicycle rear axle is limited to a 
narrow range. The MOLLER device would be expensive to manufacture and 
prone to become damaged, because of it being made of several separate 
parts. 
U.S. Pat. No. 2,793,877 issued in 1954 to MEIER shows an auxiliary wheel 
which is mounted near the rear bicycle rear wheel by means of a generally 
L-shaped flat spring blade. The vertical leg of the L-spring blade and 
that of a second, rigid L-blade are anchored to the bicycle rear wheel 
axle. The transverse leg of the rigid blade overlying the transverse wheel 
axle leg of the flexible blade is movably connected to this flexible blade 
transverse leg by an adjustable length vertical member. Again, the 
relative angular play between the auxiliary wheel axle and the bicycle 
rear wheel axle is quite limited with the MEIER system, notably by the 
fact that the auxiliary wheel axle motion is limited to a downward motion 
relative to the horizontal leg of the rigid L-blade (which remains 
parallel to the bicycle rear wheel axle). The use of a blade spring 
requires the provision of the second rigid blade and of legs to prevent 
travel of the blade spring in a horizontal plane either forward or 
backward. 
In both these above noted patents, the auxiliary wheels are functional, but 
they are complicated in that they necessitate a plurality of parts for 
installing the side wheels on the bicycle (e.g. brackets or the like, 
spindles or the like, springs, etc.). It is much more complicated to 
install the side wheels due to the number of parts involved and it is more 
probable that a breakage will occur for the same reason. Moreover, the 
spring adjustment means for the auxiliary wheels provide either upward 
adjustment or downward adjustment, but not both. Also, neither the MOLLER 
nor the MEIER reference would seem to enable the bicycle rider to deal 
effectively with a particular ground surface where the bicycle main rear 
wheel would engage a groove in the road while both auxiliary wheels would 
remain at a raised ground level; it would appear that in such a case, the 
bicycle main rear wheel may lift slightly from the ground, thus 
compromising ground traction. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide an auxiliary wheel assembly 
for a bicycle which will stabilize the bicycle in a generally vertical 
position, particularly at low speed. 
It is another object of this invention that the auxiliary wheel assembly 
comprise spring attachment means to allow an almost constant contact of 
each of the two auxiliary wheels to the ground. It is an important object 
of this invention to provide attachment means for removably attaching the 
side wheels on the bicycle, that are simple and can be easily installed 
on--and removed from--a bicycle. 
It is yet another object that the attachment means for removably attaching 
the side wheels to the bicycle consist of a single structural part. 
An important feature of the invention is to provide an auxiliary wheel 
assembly for a bicycle, which will include spring means enabling both 
upward and downward angular adjustment of the auxiliary wheels relative to 
the bicycle main wheel. 
Another important feature of the invention is to increase the safety of 
operations of bicycles fitted with auxiliary side wheels. 
In accordance with the objects of the invention, there is provided an 
auxiliary wheel assembly to be fitted to a rear wheel axle of a bicycle 
for providing lateral dynamic stability of the bicycle, a pair of such 
wheel assemblies adapted to be used concurrently on opposite respective 
lateral sides of the rear wheel axle, each wheel assembly comprising: an 
auxiliary wheel; a bracket member; anchoring means for releasably 
anchoring the bracket member transversely to the rear wheel axle; and an 
attachment member comprising an upper vertical portion connectable to the 
bracket member, an intermediate helical spring portion and a lower 
substantially horizontal spindle portion substantially parallel to the 
rear wheel axle, the auxiliary wheel being mounted to an end of the 
spindle portion, and the helical spring portion comprising at least about 
one and a quarter tightly wound turns having a longitudinal axis extending 
substantially in a forward direction of the bicycle, whereby the auxiliary 
wheel is free to move substantially vertically while rotating about the 
longitudinal axis of the helical spring portion. 
Preferably, the attachment member is made of a single piece of shaped 
structural rod. The helical spring portion may be wound in the forward 
direction, such that the spindle portion is supported by the spring 
portion against rearward movement. Preferably, the helical spring portion 
comprises about two and a quarter turns. The spindle portion may naturally 
extend about 5.degree. downwardly from the horizontal (i.e. an angle of 
95.degree. is made between the vertical portion and the spindle portion), 
in such a way that as weight is applied to the auxiliary wheel the spring 
portion flexes and the spindle portion moves upwardly towards the 
horizontal. 
Also preferably, wheel adjustment means may be provided for adjusting a 
position of the auxiliary wheel on the spindle portion to accommodate 
riders of different weight. The wheel adjustment means may comprise a 
sleeve member slidingly engaged over the spindle portion, the auxiliary 
wheel being rotatably mounted over the sleeve member. Height adjustment 
means may also be provided which cooperate with the bracket member and the 
anchoring means, for varying a distance between the rear wheel axle and 
the spindle member, to fit bicycles of varying rear wheel sizes. The upper 
vertical portion of the attachment member may comprise an inversely 
U-shape rod member, the anchoring means including a nut member threaded 
onto an axle bolt of the rear wheel axle, and the bracket member 
comprising a bracket assembly cooperating with the nut member for fixedly 
releasably sandwiching the U-shaped rod member. The sleeve member may be 
slidably mounted along the spindle portion, and locking means may be 
provided for adjustably locking the auxiliary wheel at a selected position 
along the spindle portion. The locking means may include a set screw 
member threadingly engaging through a complementary transverse threaded 
bore made in the sleeve member. 
The invention also provides an auxiliary wheel assembly to be fitted to a 
rear wheel axle of a bicycle for providing lateral dynamic stability of 
the bicycle, a pair of such wheel assemblies adapted to be used 
concurrently on opposite respective lateral sides of the rear wheel axle, 
each wheel assembly comprising an auxiliary wheel; a rigid outer bracket 
member; an anchoring rear wheel axle nut for releasably anchoring the 
bracket member transversely to the rear wheel axle; and an attachment 
member comprising an upper vertical inverse U-shaped portion made of 
unitary shaped structural rod and adapted to be sandwiched between the 
bracket member and a tine of the bicycle holding the rear wheel, with the 
rear wheel axle positioned inside the U-shaped portion, and a lower 
substantially horizontal spindle portion substantially parallel to the 
rear wheel axle, the auxiliary wheel being mounted to an end of the 
spindle portion, and the upper vertical portion being mountable to the 
bicycle within a range of positions to provide for an adjustable mounting 
for accommodating different rear wheel diameters. The anchoring wheel axle 
nut may also comprise a quick release mechanism.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
FIGS. 1 and 2 show a conventional bicycle 10 comprising a rigid frame 11 
carrying a rear wheel 12 over ground G by axle 14. 
Bicycle 10 is equipped with a pair of auxiliary side wheels 16, which are 
smaller in diameter than rear wheel 12. Wheels 16 are to be positioned on 
each side of rear wheel 12. Wheels 16 are rotatably mounted on 
corresponding auxiliary side wheel attachment means 18 which are fixedly 
and removably anchored to opposite ends of axle 14 of bicycle 10. Spring 
attachment means 18 therefore link auxiliary side wheels 16 to bicycle 
frame 11. 
FIGS. 3 and 4 show that each side wheel attachment means 18 has an upper 
elongated inversely U-shaped end 20, an intermediate helical spring 22 and 
a lower auxiliary wheel spindle end portion 24; and the spiraling axis of 
helix member 22 extends also transversely, relative to each leg 20 and 24 
of the spring member 18. As shown in FIG. 4, all elements 20, 22 and 24 
are almost coplanar to each other in end view, but form in natural 
unbiased condition an L-shape in plan view (FIG. 3). Accordingly, helix 
member 22 constitutes spring means that enable legs 22 and 24 to move 
toward or away from each other. FIG. 3 shows the wheel attachment member 
18 in the released or unbiased condition of the helix part 22, where legs 
20 and 24 make approximately a right angle, and preferably 95.degree., 
relative to each other. In the released condition of FIG. 3, helix part 22 
will yieldingly enable forcible movement of legs 20 and 24 toward one 
another, or forcible spreading apart displacement of legs 20 and 24, yet 
will bring legs 20 and 24 to their 95.degree. relative angular condition 
illustrated in FIG. 3 as soon as the forcible bias on legs 20 and/or 24 
has been released. The angle between legs 20 and 24 may range between 
preferably 85.degree. to 100.degree.. Preferably, the spindle portion 24 
is at the front of the coil spring 22 so as to prevent rearward bending of 
the spindle 24. 
Side wheel attachment means 18 is made from a single structural rod folded 
to the desired shape. Indeed, U-shaped end 20 and auxiliary wheel spindle 
24 integrally form the two extremities of helical spring 22. Therefore, 
side wheel attachment means 18 can be easily constructed and installed as 
a result of their structural simplicity. 
The inversely U-shaped part 20 of spring attachment 18 is brought sideways 
of bicycle wheel 12, generally parallel thereto, so that the threaded free 
end portion 14a of the bicycle rear axle 14 engages freely between the two 
side legs 20a, 20b of U-part 20, through and laterally exteriorly beyond 
the plane of U-part 20 (see FIG. 1). 
A generally flat bracket 26, having an axle bore 26a and a rear tab 26b 
fitting into the axle bolt receiving slot of frame 28, is applied flatly 
against the exterior side of part 20, with axle end portion 14a extending 
through bore 26a. A nut 27 is then screwed on axle end portion 14a, to 
fixedly anchor U-part 28 transversely to axle 14 and parallel to wheel 12. 
It is understood that the vertical distance between web 20c of wheel 
attachment part 20 and securing wheel axle 14 will be adjustable as a 
function of the diameter of the bicycle rear wheel 12, to fit bicycles of 
different sizes. 
Bracket 26 preferably has a generally C-shaped cross-section, and includes 
elongated inner grooves for partial circumferential engagement around the 
side legs 20a, 20b of U-shaped part 20, so as to properly hold U-shaped 
part 20 by trapping it between bracket 26 and a parallel frame structure 
28 of bicycle main frame 11. Therefore, side wheel attachment means 18 are 
removably anchored to bicycle 10. Thus, it is possible to adjust the 
height of side wheel attachment means 18 relative to rear wheel 12 by 
releasing nut 27 and then sliding side wheel attachment part 20 between 
bracket 26 and frame structure 28. When the desired relative position is 
found, nut 27 is installed and tightened once again. 
Each side wheel 16 is rotatably freely mounted on its corresponding spindle 
24 near its outer end, for a proper lever length. As suggested in FIGS. 
1-2, two laterally spaced nuts 23 and 25 are fixedly releasably engaged to 
spring leg 24, to define a gap therebetween for free rotational engagement 
by the hub 16a of wheel 16. The intergap between releasably fixed nuts 23 
and 25 should be small enough to prevent accidental partial tilt of wheel 
16 away from its operative plane orthogonal to spring leg 24. A longer 
distance between side wheel 16 and helical spring 22 will result in a 
greater lever for applying torsional tension on spring 22, meaning that it 
will be easier to force side wheel 16 upwards, since a force applied near 
the exterior outer end of spindle 24 will result in a greater torque in 
helical spring 22 than if the force were applied on spindle 24 near 
helical spring 22. Therefore, it is preferable to position side wheel 16 
near the extremity of spindle 24 to obliviate the necessity of having a 
helical spring 22 with an increased number of whorls or choosing a 
material with a greater inherent elasticity for the construction of side 
wheel attachment means 18. 
In use, the setting of the height of attachment means 18 relative to rear 
wheel 12 will preferably raise rear wheel 12 slightly above ground level, 
as shown in FIG. 1, while there is no rider loading bicycle 10. Therefore, 
side wheels 16 will be, under most circumstances, in contact with ground G 
at all times, since the weight of bicycle 10 will cause helical spring 22 
to apply a continuous downward pressure on side wheels 16. When a rider 
mounts bicycle 10, adding its weight to that of bicycle 10, helical 
springs 22 will yieldingly twist to allow rear wheel 12 to come in contact 
with ground G. Thus, this torsional tension level in helical springs 22 
will bring spring legs 24 and 28 slightly toward one another, from 
95.degree. to about 90.degree., to confer a proper amount of downward 
pressure on wheels 16 for constant contact of the latter with ground G 
while rear wheel 12 will also stay in contact with ground G for propulsion 
of bicycle 10. 
If ground level G is uneven, side wheels 16 may move upwards or downwards 
to compensate for the ground unevenness, while the combined rider weight 
and helical spring 22 action always keeps all three rear wheels 12, 16, 16 
in contact with the ground. 
It is clear from inspection of FIGS. 5 and 6 how the present invention 
improves lateral stability and ground traction of the bicycle, even at low 
bicycle speeds or in stationary condition, since the bicycle main rear 
wheel always remains positively engaged with ground, whatever the 
particulars of ground terrain unevenness. Moreover, because there is no 
second link member between the auxiliary wheel and the main wheel axle--as 
in the prior art patents discussed in the previous "background of the 
invention" paragraph--the circular play of the auxiliary wheel will be 
considerable. Indeed, nothing would prevent the auxiliary wheel 16 under a 
heavy terrain gradient, from upwardly pivoting about the helix part 22 of 
the attachment spring to a location proximate the main wheel axle 14 and 
almost orthogonal to the plane of main wheel 12. It is this wide level 
range of adjustment which is so advantageous for the auxiliary wheel 16. 
FIG. 7 shows a second embodiment of the invention, wherein the hub 16a of 
side wheel 16 is rotatably mounted over a sleeve member 30 which is 
slidably adjustable along the length of side wheel spindle 24 (as 
suggested by the arrows). Sleeve member 30 can be locked at a particular 
axial position along spindle 24 by means of a set screw 32, which is 
inserted in a complementary threaded bore 34 made at an integral enlarged 
end portion 30a of sleeve 30. A concave cap 36 fits the exterior end of 
shaft 24 to prevent accidental shearing injuries and to prevent side wheel 
16 from sliding off from wheel spindle 24, either during the adjustment of 
side wheel 16 or during its use, if set screw 32 was not installed tightly 
enough. 
The purpose of this adjustable position of side wheel 16 with set screw 32 
is to set a desired lever length between side wheel 16 and helical spring 
22. This adjustable lever length is advantageous, for it allows riders of 
different weights to use bicycle 10 equipped with side wheels 16. Indeed, 
the weight of a rider must be sufficient, when added to that of the 
bicycle, to allow rear wheel 12 to stay in contact with ground G and 
confer effective vehicle wheel traction to rear wheel 12. A lighter rider 
will necessitate a longer lever length than an heavier one, for a given 
torsional tension in helical spring 22, to allow rear wheel 12 to come in 
contact with ground G. It is thus possible to adjust the position of 
auxiliary side wheels 16 to fit different riders for a maximum efficiency 
of side wheels 16. It is understood that it would be possible to mark a 
graduated scale along spindle 24 as a function of the rider's weight so 
that the desired position of side wheels 16 could be easily found. 
Such an auxiliary wheel assembly will increase the safety margin of the 
bicycle rider, who will therefore feel more confident and should learn 
faster how to operate and handle the bicycle. 
The attachment elements 20, 22, 24, in the preferred embodiment are made 
from steel rod having a diameter of 0.281" (7 mm) and a Young's modulus of 
207 GPa. The steel is preferably OTMB steel and is painted with heat dried 
paint. The length of the spindle portion is 5" (12.7 cm) from the vertical 
portion; while the interior diameter of the coils is 1.75" (4.45 cm). 
These elements could be made of any suitable resilient material, e.g. leaf 
tempered steel rod, or a resilient sturdy semi-rigid plastic rod material. 
The tread band 16c of auxiliary side wheel 16 could be made from plastic 
or from an elastomeric material, while the auxiliary side wheel hub 16a 
and associated spokes 16b should be made from a lightweight rigid 
material, e.g. a sturdy plastic material. 
It is noted that, in the prior art, auxiliary wheel attachment of FIG. 5, 
multiple vertical positional adjustments of the nut N that fixedly secure 
wheel attachment A to the bicycle rear wheel main axle X, are periodically 
called upon. The reason for this is that, at given time intervals, e.g. 
two times per month, it is desirable to raise in increments the height of 
the auxiliary wheels W, so as to progressively induce in the lay rider the 
feel of lateral instability of the bicycle at low speeds thereof, while 
maintaining operating safety margins at comfortable levels. 
In the present invention of FIG. 5, on the contrary, continuous adjustments 
of the height of the auxiliary wheel 16 are automatically performed, 
responsively to road conditions. Such continuous height adjustments are 
obviously more advantageous, both for safety reasons and for educational 
goals.