The goal of this project is to design and create a rowing bike for special needs children. As a group we will go through the design process to make the best possible machine we can. We will be keeping in contact with our contact to make sure it meets all of their specifications. We will be working together to complete each part of this project.
We currently have three different designs that we believe will work. The problem with the design that was made last year is that it has a problem going smoothly while pushing the handle back forward. In our three designs we feel like we have fixed that problem. It is now all about choosing which one would work the best and be the most cost efficient.
According to the CDC 20% of special needs children are obese. One main reason for this is because they do not participate in sports or other active activities like children without special needs do. This includes riding a bike, a scooter, or other things. With this project we will design a rowing bike for these children. This will allow them to be outside and active. We hope that this will not only allow them to be more healthy but to also have fun while riding this bike. Our bike will be a rowing bike with push and pull functions. This will allow for the children to receive feedback for both mechanisms of the bike.
-Driven using a more natural lateral motion rather than typical rotational motion of a traditional bicycle
-Low center of gravity
This design is made for more of a person who usually rows in the water, or is accustomed to a row machine at the gym. It is a good design but only turns the wheels when you pull on the handle, rather than creating a driving force in both the push and pull directions. This bike also steers by you moving your body left to right. This design may be something to look at but it will need significant modifications to be able to fit what we need to do based on the design specifications.
This design is very well thought out. The main problem is the steering component and that it only turns the wheels when you pull the bar. Another problem with this bike is that it only has two wheels, which will lead to balance issues in our application. We believe it will be more beneficial to have 3-4 wheels to add more stabilization to the bike. We also would like to be able to steer the bike with the pull bar, or a design similar to a traditional bicycle. This will be simpler and allow the children to be able to use the bike more efficiently.
Elliptical Bike: Outdoor Elliptical Bikes and Stand Up Bikes (elliptigo.com)
This design, much like the others is based on a two wheel platform which will need to be eliminated by adding more wheels in a trike or 4 wheel configuration. The steering issue is more apt to our application as it uses the same mechanism as a traditional bicycle. The driving mechanism of the elliptical provides a 100% input to the drive wheel, as long as you are moving your legs. The free wheel/one-way bearing in the rear drive sprocket allows for coasting of the bike as well as the option to “reset” the pedal position by moving the drive mechanism in reverse.
In the first concept we created a chain driven cart that would have two sets of chains driven by a bar that would be pushed and pulled by your hands while driving. We were going to have two free wheel sprockets facing in separate directions to allow there to be an input on the rear axel during both the pushing and pulling moments.
In concept design two we made another chain driven cart. The difference in this cart and the first one is that this cart has two chains, one that goes to the front axle and one that goes to the back axle. This design would allow for another push pull cart that would have an input on both the push and pull mechanism.
This elliptical bike will be set up as a normal tricycle would be with two wheels in the back and one wheel in the front. The bike will be constructed based off an existing tricycle frame that is available for purchase, which will then be modified to eliminate the standard bicycle pedal mechanism and adapted by creating links to be able to be powered by an elliptical mechanism. We decided not to include hand pedals typically seen on an elliptical machine so that the bike was only powered by legs and feet, so that the users arms and hands can be used in the steering component of the trike. The drive system of this trike will be formed by the elliptical links, connected to the drive sprocket, which then turn the free wheel/one-way bearing sprocket attached to the rear drive wheel. It will also have a front hand brake to aid in stopping.
We selected the elliptical tricycle, Concept design 3.
The design we selected was a standing elliptical tricycle. We chose this because we wanted to have a design that would work and after talking to the contact she seemed to like the idea of an elliptical. Although it is different from the original plan of having a rowing bike, we felt that if the contact liked the idea then we should do it.
For this engineering analysis we decided to calculate the gear ratio of our elliptical bike. we determined that with every one rotation of the elliptical the back wheels would turn 2.75 times. After this we determined the bike would move 11 ft in one rotation of the mechanism.
During our second engineering analysis we were trying to find the average velocity of our tricycle. We decided that the children that were riding our bike would rotate the mechanism 30 times per minute we then multiplied this by our gear ratio and the circumference of our tires. This allowed us to find the cruising velocity of 10.781 mph.
During this analysis we used motion gen pro to find the correct lengths for each of the linkages for our mechanism. This allowed us to have set lengths for each link before we cut the aluminum.
For the fabrication of our elliptical we started with a standard tricycle. We knew we would have to extend its length to allow for our mechanism to fit inside of its frame. We did this by cutting the frame after the pedals. Once we had it cut we knew we would have to extend it 10 inches. We did this by placing a steel bar inside of the frame. Once we had the frame extended we had to fabricate our mechanism. We started by welding a rod to the frame of the bike. This is where we would put our first link and it would pivot on this rod. After we did this we fabricated all of our aluminum links and inserted bearings in them to allow for a smoother ride. We then created our foot pedals and added support to the rod that held the first link. The final thing we did was shorten the chain, paint the bike to avoid rusting, and added a foam pad for safety.
Before we modified the tricycle at all we tested the stability of the tricycle. We did this by riding it at a normal speed and making aggressive turns. After doing this we felt that the frame was stabile and was okay to use for this project. While building the elliptical we would go through and make sure to smooth off any sharp edges to make sure that no one cut themselves on the elliptical. Once we had our elliptical put together we took it for a test ride outside and saw that the tricycle was still stable with our mechanism on it. We also allowed Dr. Canfield to look over the tricycle to check for any rough spots that we may have missed. After that he rode it and though that it was safe to ride as well.
We would recommend that whenever riding our elliptical to always wear all necessary safety equipment. This includes a helmet, knee pads, elbow pads, ect. It should also be known that when riding the tricycle you should always be careful and never go beyond your limits of speed. If you are going to turn the tricycle make sure to slow down by slowly pressing the front brake. This will allow you to slow down and make a safe turn. Always be aware of your surroundings when riding this tricycle. It is made for smooth surfaces. If it is ridden in the grass it could cause for the linkages to get caught and you could be thrown from the tricycle. When riding you should always have someone else present in case of an emergency. This tricycle is to be ridden at your own risk and Robert Bond, Gabe Rogers, Brayden Hubbard, and Matthew Norman are not responsible for any injuries that may occur on this tricycle.
After creating this elliptical bike we feel that we have completed all of the design requirements. During this project we realized that modeling something on a computer and making it in person are two totally different things. There are outside factors that can determine if your design will work or not. We feel that our design will satisfy the needs of the Putnam County school system and will allow their children to have something to ride for many years to come.