Bicycle Design Challenge.

[spokeweasel]

Morning.

Not for me, but for my niece who is studying to be a Mechanical Engineer. Any new design ideas or any help in building the cycle from scratch are welcome. The idea is to cut down the raw materials and production costs. Where in the design process can we get creative? Trying to bounce off some ideas.

Had to ask in here as I see so many trying to build their own bikes or restore old cycles & should have something to share. The prototype cycle has to be under £100. That is the actual challenge.

Attached a few screenshots from the pdf file (Interesting seat post design in the master sample).

Thanks in advance.

PS : Don’t get me started on the “sexist” note (#1) under the general design requirements.

 

[Mr.B-Campag]

Is there something about Indian males that makes designing bicycles for them particularly challenging???

[Sorry, but your (very reasonable) comment about this was akin to asking some to not think about a pink elephant etc.]

 

[Punkawallah]

As it is to be a ‘bi’ cycle, do we assume two wheels?
They are restricting options by specifying ‘belt/chain drive’?

 

[mickle]

20" (406) (BMX standard) wheels are very common, can be built strong and allow for racks and therefore cargo to be loaded with a lower c of g. Smaller wheels also allow for a low step though frame design with fewer tube manipulations.

 

[Sharky]

The budget seems very small, if it's for a complete bike?

 

[Ming the Merciless]

I think you should look at bamboo for the main bicycle frame. There are online designs out there to get started. That should keep costs down leaving more for transmission and other components.

 

[lenfield]

Your niece is going to get marks for innovation so why doesn't she propose a dingle-speed bike?
It provides two robust gears at a minimal cost.


View: https://youtu.be/ef0AkZi9liI?si=nMbmo1WJRJrCT5DF


View: https://youtu.be/h1-zTUOolvo?si=m6ZSrvt3ahQarQQP&t=320

 

[lenfield]

Alternatively she could propose a retro-direct transmission. You get a high or low gear depending on whether you pedal backwards or forwards.


View: https://www.youtube.com/watch?v=26NY9NKpYws

 

[All uphill]

It's probably not an acceptable engineering solution, but I'd pick up the word "reuse" and suggest importing containers of unwanted bikes from the wasteful west.

 

[classic33]

Would direct drive to the front wheel be ruled out by the chain/belt drive requirement.

Does it have to be a diamond frame?

 

[lenfield]

Is there something about Indian males that makes designing bicycles for them particularly challenging???

[Sorry, but your (very reasonable) comment about this was akin to asking some to not think about a pink elephant etc.]

Indian males tend to be short, particularly those in the south of the country.

 

[Drago]

How about a front pedal rear wheel steer job? Direct drive to the front wheel witn no expensive chain, gears, chains etc, etc, but with a freewheel.

Rear steer could be inexpensively implemented by means of cables attached to the barcendd.

Itd probably be crap, but wee little details like that don't matter.

 

[Drago]

Indian males tend to be short, particularly those in the south of the country.

Thats because of the lower altitude.

 

[classic33]

How about a front pedal rear wheel steer job? Direct drive to the front wheel witn no expensive chain, gears, chains etc, etc, but with a freewheel.

Rear steer could be inexpensively implemented by means of cables attached to the barcendd.

Itd probably be crap, but wee little details like that don't matter.

I was thinking about something like this.

 

[lenfield]

I was thinking about something like this.
View attachment 819728

A single 28 inch gear would give a speed of 5mph at 60 rpm. It would be OK for hill-climbing but you would get overtaken by joggers.