Bicycle Design (Individual Project)

In summary, the designer wants to design and manufacture their own road bike. They have completed their final exams and are now able to focus on the project. They are asking for advice about where to begin static analysis, and have questions about computer analysis and the safety of the bike. They have some experience with bicycles, but are looking for more information.
  • #1
mastermechanic
108
15
Hello everyone, I have not been here for a long time. Now I'm here for a DIY project.

Purpose: I want to design and manufacture my own road bike and ride it as soon as possible.
I want to design nearly all parts on a bike except for the wheels, chain, saddle, cables, maybe shafts and bolts and maybe gears (they would be very hard do design, I've not decided yet).

I've completed my final exams so I can focus on this. I've lots of questions therefore I'll update here frequently. You may ask "Why don't you buy one?" but it's both in my field of interest and I want to test my engineering skills.

First of all, I'm a mechanical engineering student and finished my 2nd year. I've a good practical and technical knowledge of bicycle but not computational technical knowledge. So; if you want to design your own, this thread will be a good guidance for you.

Let's begin:

Firstly: I want to introduce you the type of bicycle I want to design & manufacture.

5ababb1255f47.jpg

This is a road bike. Simply, no suspension, speed based design, low weight.

Requirements: ------------------------------------------------------------

*
Low weight : It should not weight more than 10 - 10.5 kg Generally road bikes are between 8-9 but I'm relatively flexible.
*Design: I love the design in the pic, the top bar should look horizontal, that makes it aggressive.


*Safety: I want to be conservative as much as possible without sacrificing the lightness.

* Comfort:
That's a road bike, I'm not expecting too much comfort but it should be ergonomic.

* Material: Carbonfiber is very expensive and not suitable for my purpose, for lightness I will use aluminum on frame (T-6061 or something else, I'll research) and steel for the crank and other power unit parts.

*Life: Of course, fatigue analsis will show us the result but I want to ride this bike safely at least for 5 years.

* Performance: This is where I want to focus, low friction, low drag, low resistance. I should ride it at high speed as much as possible without getting tired. (Now, I've a mountain bike with both suspension and shock absorber, so the significant drop on weight will feel me satisfied in terms of performance.)
------------------------------------------------------------------------------------

(I didnt collect my question on a paper so I will update here when I remember hence, the order of the questions may be confusing but don't worry I will keep here neat and clean.)

Today's Questions:

1-)

Actuator:
In such a design the most challenging part is the beginning because it's very hard to find where to start. So my first request will be an advise about that. I thought the dimensions may help:
Y6PnRZ.png


I'm a tall guy, 187 cm ( 6 ft 2 in US system). So I can benefit from this table. That's ok.

I have some sketches (will share on weekend), but my main problem is that where should I being to design analysis. Because during the preliminary design, at some points I have to do static analysis (wihout computer just by hand) therefore I need some rough values which will guide me.

So, the question: In static analysis in which region should I begin to investigate?

My attempt: (Note: Of course this is very inaccurate, no bar and no shafts are rigid, the whole frame will deform together but I'm trying to get rough values about the stresses) (Correct me when I'm wrong)
6NRgLl.png

I weight around 85 kg and added addiotional 15 kg for simplicity. So the wheel axles react in 500 N, I assumed the seat bar as rigid then the triangular part is subjected to bending.
But when I do some calculations I get weird bending which are very high compared to yield strength of T-6061 Aluminum due to assumptions.
j6JEPG.png

I think my assumptions deviate somewhere if the calculations are correct. I need you help here and I leave it here for now. It's 5:12 am here :)

My first questions is above.

2-)


Computer Analysis

This is a question to be asked in the future but I want to know from now on.

Question 2: What kind of analysis do I have to do to ensure that this bike is safe for me? (Von-mises, fatigue, deflection what else? ) (I have also questions about how I should do these analysis but will ask later)

 

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  • #2
None of your images worked, except the photo of a bike. Use the UPLOAD button on the post editor to put images in your post.

What is your background and education about doing analysis and engineering?
 
  • #3
I started a bicycle thread at Linux Questions years ago. I just don't ride or have a passion for only motorcycles. My passion covers 2 wheels mostly because I like to have fun.

My Fixie.

My Schwiinn

My Fuji

Great thing about my area. Traffic is light and it is all flat. Good luck with your ideas. I have hands on shady tree experience myself.

Just my 2 cents. When incorporating your design. Keep human body mass in mind. My mind has a passion for 2 wheel transport. But my body is 6 foot 7 inches and I am a gorilla at 270 lbs. That does not stop me from riding bicycles how ever.

Here is my thread in case you need ideas.

https://www.linuxquestions.org/questions/general-10/the-bicycle-thread-4175544046/
 
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  • #4
anorlunda said:
None of your images worked, except the photo of a bike. Use the UPLOAD button on the post editor to put images in your post.

What is your background and education about doing analysis and engineering?

Can't you see the pics? I can upload here again because somehow I can't edit the original post.

As I said I'm mechanical engineer student. (sophomore). I have not been in such an experience before. In the context of lecture, I've completed Mechanics of Materials I & II. I'm familiar with CFD analysis (Autodesk CFD). I'm able to use Solidworks but planning to use it for modelling. For the static and fatigue analysis I will use ANSYS. (I'll learn to use).

A bicycle includes dynamic parts, I haven't taken Dynamics & Control yet but since I have lots of source (books etc.) I'll learn the part that is enough for this Project.

I uploaded here the pics. (In order)
 

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  • #5
mastermechanic said:
Can't you see the pics?
Yes thanks, I can see the pictures you posted in #3.

I'll let others comment on which analyses you need.
 
  • #6
Don't you think the rear 500 N should be bigger than the front 500 N?
 
  • #7
Not to mention the shocks caused by bumps in the road might be a lot higher than static loads?
 
  • #8
Merlin3189 said:
Don't you think the rear 500 N should be bigger than the front 500 N?

Yeah I forgot the weight distribution. Thanks!
 
  • #9
CWatters said:
Not to mention the shocks caused by bumps in the road might be a lot higher than static loads?

Okay, that's good point thanks! How can I calculate or simulate that shocks to get data?
 
  • #10
Measuring the shocks is probably the best way but...

Some bikes have suspension so you could measure the force required to compress a typical sadle or fork spring. My bike had a spring sadle post and I don't think it's ever bottomed out so typical forces must be less than that required to compress the spring fully.
 
  • #11
Since you are using full triangles there should be no bending stress on any of the frame elements only tensile and compressive loads and stresses as shown in your analysis diagram; therefore the resulting stresses should be calculated used the following simple formula: σ = Force / x-sectional area of the material of the structural element.
 

Related to Bicycle Design (Individual Project)

1. What is the process for designing a bicycle?

The process for designing a bicycle typically involves several steps. First, the designer must research current trends and technologies in the industry. Then, they create a concept sketch or 3D rendering of the bike. Next, they build a prototype and test it for functionality and performance. Finally, adjustments are made based on the test results before the final design is produced.

2. What materials are commonly used in bicycle design?

The most commonly used materials in bicycle design are steel, aluminum, carbon fiber, and titanium. Each material has its own unique properties and advantages, so designers often use a combination of these materials to create a well-rounded and high-performing bike.

3. How do you ensure a bicycle is aerodynamic?

To ensure a bicycle is aerodynamic, designers use various techniques such as wind tunnel testing and computer simulations. They also consider factors such as the bike's frame shape, wheel size, and positioning of the rider to reduce wind resistance and improve speed.

4. What safety features should be incorporated in a bicycle design?

Safety is a crucial aspect of bicycle design, and there are several features that can be incorporated to ensure the rider's safety. These include using high-quality brakes, adding reflectors and lights for visibility, and designing a sturdy frame that can withstand impacts.

5. How do you make a bicycle comfortable for the rider?

In order to make a bicycle comfortable for the rider, designers consider factors such as frame geometry, handlebar and seat positioning, and suspension systems. They also take into account the rider's body measurements and riding style to create a bike that fits their needs and preferences.

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