1. Bike Riding Stand & Hitch
MAE 377: Product Design
Peter J. Flood
Thomas J. Froehlich
Umberto M. Lumbrazo
Jacob T. Matrachisia
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2. Introduction
Problem Identification:
The weather in upstate New York can be harsh at times, preventing people from getting their
proper amount of daily exercise. Therefore, what is the most affordable machine for exercising
indoors? Treadmills, ellipticals, and stationary bikes are the most common forms, but can be
extremely pricey from $200 to $1000 or can be used with a membership to a gym with monthly
fees. By adapting a bike rack, previously used for efficient indoor storage, any bike can be lifted
off the ground and used as if pedaling down a road. With this product any current bicycle owner
can also own an indoor stationary bike as if at a gym, but with the comfort and familiarity of their
personal bicycle. However when the weather is bad some people just leave the area for a
vacation in warmer weather. Transportation of this product is easy because the base of the
stand can be removed and switched with a car hitch attachment. This product allows for two
existing products to become one. In an instant an indoor riding bike stand can turn into a car’s
bike rack.
Product Description:
The Indoor Bike Riding Stand is an adjustable bicycle stand for all size bikes and people. It is
able to securely grasp any bike off the ground with an adjustable clamp fixture and stand. The
clamp closes onto a bike’s frame and is then connected to the top of the stand. The stand is
then lengthened or shortened, depending of the size of the bike, so that the rear tire rests on the
wheel track. This stand is located under the bike and behind the front wheel. The rear wheel
rests against a wheel track that provides resistance and spins as the bike is pedaled. The front
wheel is placed in a separate valley shaped fixture to prevent any movement. The bike is then
used as if outside on the road or at a gym on a stationary bike. The bottom of the stand can
detach and a
L-Shaped part can be attached to connect to a trailer hitch for transport.
Product Comparison:
The advantages of this product are that it is universal to anyone who owns a bike. It is a cost
efficient alternative to existing indoor cardio machines. It allows training in the off seasons for
bike owners, which could help a bicyclist become more adept and familiar come race time.
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3. A similar product is the ​Conquer Indoor Bike Trainer Portable Exercise Bicycle Magnetic Stand.
(​https://www.amazon.com/Conquer-Trainer-Portable-Exercise-Magnetic/dp/B0094KIVQW​)
This product has the same function but uses less material to secure the bike in an upright
position. While my design has the wheel track separate from the stand, this product is designed
as one. This design is more cost efficient for a bike-riding stand. It may be more efficient, but my
design is not just a stand. It is even more advantageous because it is a cross between two
existing products. ​If you want to take your bike on a trip, just pull the bike off the base and place
it on the hitch attachment already hooked to your vehicle. The other pieces can be left behind. It
is a two in one product because many people own a car bike rack such as this Thule rack.
This is the Thule car rack.(​https://www.etrailer.com/Hitch-Bike-Racks/Thule/TH934XTR.html​)
The hitch is limited to carrying only one bike while the Thule car rack is able to fit up to 4 bikes.
Therefore this product might not be as ideal for a large family with multiple bikes. Also more
disadvantages of my product are that it is a requirement to first own a bike and repetitive use
will wear out the bike’s back tire.
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4. Assembly Drawings:
Front Tire Holder Assembly
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5. Stand Assembly
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6. ​Hitch Assembly
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7. Rear Tire Base Assembly
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8. Bill of Materials:
Part number Part Name Quantity
1 Hitch insert 1
2 Hitch Brace 1
3 Rotating Hitch 1
4 Adjustable stand 1
5 Bottom clamp 1
6 Top Clamp 1
7 Removable handle 1
8 Rear wheels 5
9 Rear Tire Base 1
10 Rear Tire Base Support 2
11 Front Tire Holder 1
12 Front Tire Strap 1
13 Base 1
14 Spring loaded pin 1
15 Bottom Clamp pin 1
16 Base pin 1
17 Hitch rotational pin 1
18 Hitch holder pin 1
19 Brace bolt 1
20 ¼” Nut 2
21 Rear wheel pin 5
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9. Analysis
Preliminary Design Analysis:
When approaching the idea of a riding bike stand the biggest design issue was securing
the bike without interfering in the bikes or user’s movements. However, at the same time the
stand needed to be stable and able to hold at least 300 lbs. I considered a bike rack that was
fixed on a wall in one or two locations then attached to the bike’s frame under the seat and
under its handlebars. This design was flawed because it could only be installed once for a
specific bikes length and it is dependent on the walls strength as well. Both of these limit the
practicality and adjustability of the product. It also would have made the hitch attachment for the
car more complicated and harder to use. While the design I chose does not require any
installation, only an assembly and the hitch is simpler.
This product successfully provides an alternate solution to exercising indoors. The
Indoor Bike Riding Stand is the perfect economic solution compared to treadmills and other
indoor cardio machines. Environmentally the only byproduct of the stand will be a small amount
of rubber burning off the back tire as the wheel spins on the track overtime and will save the
amount of gas it takes to drive to a gym for exercise. As long as the stand can properly support
the bike and the consumer, this product meets health and safety needs very well. I based my
design off of gym equipment that can hold tremendous amounts of weight. Therefore the stand
should be sustainable and the parts required should be easily manufacturable by companies
such as Precor (​http://www.precor.com/en-us​) and Quantum Fitness
(​http://www.quantumfitness.com/​).
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10. FEA:
Jacob Matrachisia:
I applied a force of 283 lb to the top pin and flat top of the bar. This is the estimated weight of a
250 lb human and a 33 lb bike. I also constrained it at the top pin hole and bottom pin hole
because the pins will hold the weight and keep it from collapsing on itself. The pins and
adjustable stand converged in both trials, but there could be some improvements in my first trial.
My original design was half as thick because I was trying to use the least amount of material
possible. It converged, but deformed a lot and struggled to hold the weight. I doubled the
extrusion and made it ⅛ in thick all the way around instead of 1/16 in. After running the tests
again it converged better and improved the overall design of the part.
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11. Umberto Lumbrazo:
One of the most critical components of the project is the bottom clamp. This part is suppose to
be strong enough to support the weight of up to a 250 pound rider and their average bike
weighing about 33 pounds. For setting up the analysis on the part i used the top wall in the cut
out and the pin holes as constraints and applied the whole 283 lb force onto the saddle where
the bike frame will be resting. We decided to use steel for this part because of the size of the
forces being applied onto such a small area. To help better the convergence I added a triangle
to the bottom of the saddle for extra support and then I rounded the edges. I found that after
making these changes i was able to see that my max displacement on the part was much less
and there were less internal strains in the part. Which makes sense because of all of the added
material and the shape of the added material.
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12. Thomas Froehlich:
I used a bearing force of 35lbf on the inside of the pin hole in the -Y direction. This is the high
end of a bikes weight. I constrained the bottom two edges of the triangle that will be resting on
the hitch insert. The hitch brace used a lot of material so for the redesign i decided to take out
some of the material above and below the pin hole lowers the cost of materials. I rounded the
edges to avoid having sharp corners which will lower the allowable stress on the part.
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13. Peter Flood:
A force of 283 lbf was placed in the negative z-direction on the inner hole surface where
the pin is inserted and rests on. The bottom large square surface was fully constrained because
it will be flat on the ground. When assembled the adjustable stand’s hole and the base’s hole
will be aligned and then held in place by this pin. Therefore this surface location will support a
majority of the rider and bikes weight when the product is in use. To determine the load we
chose 250 lbs for the maximum allowable weight of a rider, plus 33lbs as the maximum weight
of a bike.
FEA Without Rounds and Chamfers:
In this case no rounds of chamfers were added to the drawing. For convergence to be
achieved the polynomial order was increased to 9 with the percent convergence at 1. Due to all
of the sharp edges there is a design flaw that will cause the simulation to fail if operated at lower
polynomial orders and higher percent convergences.
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14. FEA With Rounds and Chamfers:
To improve the design I added 4 fillets on each inside corners along the rectangular
shaft. I also added a chamfer around the profile edge of the top​ ​surface in the large square.
Because there were less sharp edges, the simulation was able to converge at a polynomial of 6
and a percent convergence of 10. This simulation only took 6 passes and had no errors as in
the previous FEA.
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15. GD&T:
Part 1:
I chose datum A as the right side because it is has the largest surface area and fit into a trailer
hitch. Datum B is the top because it has the second largest surface area that will interact with
the hitch brace. I put a perpendicular tolerance between A and B in order to keep the two
surfaces at a 90 degree angle. Datum C is the datum on the front of the surface which has the
least surface area. C is perpendicular to both A and B to keep the edges square.
Part 2:
Datum plane A is the top surface on the back of the hitch brace. I chose this because it has the
most surface area contact with the hitch inset. Datum plane B was the vertical surface of the
brace because it had the second biggest surface area. Datum C is the side of the trIangular
member. This feature is important because it contain the whole that will connect to the rotating
hitch. And finally Datum D is the top of the brace where the connection with the rotating hitch is
present with a pin to hold it from rotating. All of the holes on this part have a to upper limit of .25
and a lower limit of 0.
Part 3:
This part has various assembly locations. Datum A (primary) was chosen with a planar feature
because it has the greatest surface area and can easily relate to the other assembly locations.
Datum B and C were chosen with perpendicular features to completely constrain rotational &
translational motions. The datums of D & E are necessary to find and then limit the location of
the holes on either surface with the true position feature. Both are then related to the datum
reference axis formed by A,B, and C with the parallel datum features. This is possible because
the D datum plane is parallel to A and E is parallel to C. Next each holes position is constrained
by the true position feature and referenced by the following primary, secondary and tertiary
datums involved. Every hole is a RC1 clearance fit and the limits were taken from the
corresponding table given in the notes. Every other dimension is basic and is limited by the
table in the bottom right. This part may now be reproduced according to gd&t standards.
Part 4:
Datum A was chosen because it has the greatest contact area with other parts. This surface
goes over the base plant and is connected by a pin and also goes into the bottom clamp with a
pin. Datum B was chosen because it has the next most contact with other parts. This surface
needs to be perpendicular with datum A or else the parts will not fit together. C was selected for
the pin holes. This need to be accurate so the pins fit into the holes correctly.
Part 5:
The reason why Datum A was chosen as the primary plane was because it has the most
surface area in the part and it interacted with other planes. Datum B was selected because it
was the second biggest plane and interacted with datum A. Datum B was chosen to be the
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16. secondary and have a flatness attribute because many of the other dimensions and datums
were based off of it, and the side needed to be specific. I chose Datum C to be the tertiary and
have a perpendicular restraint with respect to datums A&B with because many of the
dimensions come from the back edge so if perpendicularity needed. Lastly I chose my true
position datums to be located in the centers of the two most important holes with respect to
datums A,B&C because the size and placement of the holes were plotted off of those planes.
Part 6:
I chose datum (A) to be the primary datum because it had the most surface area running
through the part, and almost every dimension was based off that datum A, this datum was
chosen to have the flatness because it was the primary. Then i chose datum B to be the
secondary and to have a perpendicularity attribute towards a because both those planes contain
most of the dimensions. Then I chose datum C to be the tertiary and have an angular attribute
because many critical dimensions come from and the placement of the removable handle. Then
I chose the hole to have a true position hold because it is a necessary fit, and if the hole
dimensions are off the part will not operate as expected.
Part 7:
I chose datum A to be the primary because it had the largest area of interaction between the fit
of that part and the top clamp, i also chose this datum to have the flatness attribute because it
was the primary. Then I chose datum B to be the secondary datum because it had the second
largest area of interaction, I also chose this to have a perpendicularity attribute. Then i chose
datum C to be the tertiary datum plane because it had the least amount of contact with other
parts, and i also made this one have a perpendicularity attribute with a most material limiting
factor as well.
Part 8:
The Primary datum, A, was chosen because it has the most surface area and will have to fit into
the rear wheel base. It has a flatness tolerance of .01 so it cause slide into the real wheel base
without interference. Datum B is an Axis datum within the whole. It has a perpendicular
tolerance to make sure the whole is straight across so that the pin can fit into it. There is also a
cylindricity tolerance in the hole to make sure the pin will fit.
Part 9:
The primary datum was chosen because 5 pins and the rear wheel base supports are
assembled through this surface. A planar feature was then used because it is necessary for a
primary datum. The Secondary and tertiary datums were chosen as the bottom and side face
with perpendicular features to fully limit translational and rotational motion. Next a profile feature
was needed to limit the curved top of the object. Finally every hole’s location was limited by the
true position feature according to the datum reference axis formed by A, B and C. Each hole’s
dimension has a clearance limit specified by the table in RC1. Every other dimension is basic
and relates to the table in the bottom right.This part may now be reproduced according to gd&t
standards.
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17. Part 10:
This part is cylindrical and the important surface for assembly is the smaller cylinder. Therefore
the primary datum is assigned with a cylindricity feature to the surface of the smaller cylinder.
Next, rotational and translational motion can be fully constrained by the datum plane B with a
perpendicular feature. The limit on the shaft diameter is determined by a RC1 fit. All other
dimensions are basic. This part may now be reproduced according to gd&t standards.
Part 11:
Datum A has the largest surface area of this part. It comes in contact with part 12 and has to be
accurate in flatness. Datum B has to be perpendicular to datum A. Datum C is perpendicular to
A and B.
Part 12:
Datum A is the largest plane of this part. Datum B is perpendicular to datum A and they have a
necessary requirement of flatness to it.
Part 13:
The primary datum (A) was chosen because it has the greatest surface area and is assembled
on this plane one of the most important support pins. Flatness is used on A so it can be
reproducible. Datum B is the secondary because it has the most surface area on datum A. To
relate and control datum B to the primary datum a perpendicular feature is used. Datum C is the
tertiary because it has the least surface area but is important in assembly with the adjustable
stand. Another perpendicular feature is used to relate C to datums A and B. Finally a true
position feature is used for the location of the hole in relation to all datums present. With all
datums present, the part is fully constrained with zero rotational and translational motion. An
RC1 limit is then applied to the dimension. This part may now be reproduced according to gd&t
standards.
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