Safety regulations for motorcycle frames

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Discussion Overview

The discussion revolves around the safety regulations and specifications for motorcycle frames, particularly in the context of a midterm project using Autodesk Inventor. Participants explore the availability of official guidelines from government bodies or engineering associations, as well as practical insights into motorcycle design and construction.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant inquires about government or engineering specifications for motorcycle frames, noting a lack of useful information beyond NHTSA guidelines for imported motorcycles.
  • Another suggests that regulations may vary by location and encourages the inquirer to research custom builders and local laws.
  • Participants mention the importance of design elements like rake and neck angle, warning that aesthetics can compromise safety.
  • Links to Wikipedia and other resources are shared, highlighting geometry and dynamics relevant to motorcycle design.
  • Some participants express skepticism about finding formal specifications for custom-built motorcycles, suggesting that innovation should not be constrained by prescriptive design procedures.
  • Discussion includes differing opinions on the use of Autodesk Inventor versus AutoCAD for design work, with some advocating for the latter for initial scheming.
  • One participant shares a perspective that there are no formal specs for custom-built vehicles, emphasizing the need for basic roadworthiness standards instead.
  • Another participant mentions the UK’s "Road Vehicles (Construction and Use) regulations" but notes the absence of specific motorcycle documents, indicating that regulations focus on compliance rather than design methodology.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of formal specifications for motorcycle frames, with multiple competing views on the importance of regulations versus innovative design practices. The discussion remains unresolved regarding the best approach to ensuring safety in custom motorcycle construction.

Contextual Notes

Participants express uncertainty about the availability of official specifications and the implications of local regulations. There is also a recognition that design processes may vary significantly based on individual approaches and project requirements.

jamesson
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Howdy folks

Pardon any implicit or explicit stupidity in advance.

I'm an EE major taking a class in Autodesk Inventor, and I'm probably going to do a motorcycle frame for a midterm project. While it will not be required, I'm curious to see if I can make something roadworthy. Does any government body and/or engineering association publish specifications for this particular thing? I found something by NHTSA about _imported_ motorcycles, but nothing yet about manufacture.

Thanks much in advance

<< Personal information deleted by Moderators >>

PS - what is the general take on Inventor? I have to say, after hating Autocad with the burning passion of a thousand suns I find it to be a very welcome alternative. I only wish it did thermodynamic simulations, but I guess that's what multiphysics is for.
 
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You should start Googling right now on motorcycle frames. Custom-builders like Jesse James can start from the ground up, but often buy pre-built motors and power-trains. There might be stricter regulations where you live, so don't generalize. Good luck, and have fun.
 
Well, that's how I found the nhtsa stuff. But nothing looked useful yet.

Gonna repost this in auto engineering, seems like a better fit.
 
Good luck! Remember to check engineering threads about rake/neck-angle, too. Some scary things can happen when you try to drive a bike that has been built to "look good"
 
Wow - wikipedia has a practical use - shocking!

http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_geometry
http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics
http://en.wikipedia.org/wiki/Motorcycle_fork

Additionally

http://www.motorcycle.com/how-to/chassis-alignment-basics-3444.html
http://www.knucklebusterinc.com/tech/FrameFabrication.pdf
http://www.eng-tips.com/viewthread.cfm?qid=62470

Thanks for the rake angle tip - a big help! Still, would be nice to have something a bit more official. Surely enough rich lawyers buy bikes at this point that somebody may have demanded a formal spec by now?
 
You're welcome. A lot of backyard "customizers" have built tank-slappers that would kill all but the most experienced riders.
 
jamesson said:
PS - what is the general take on Inventor? I have to say, after hating Autocad with the burning passion of a thousand suns I find it to be a very welcome alternative.

As much as I used to say I hate it. AutoCAD is amazing. It just requires a different thought pattern to parametric modelling.

The reason why you think it's no good is because you've never done a proper design scheme of a system yet. One day you'll be forced to use AutoCAD for 2d scheming, and you'll get what I mean.I have a pdf copy book somewhere on motorcycle dynamics.
I'll have a look.

You don't have to read it all, but it'll be a good reference.You'll never find a 'spec' for a bike, just like you won't have a spec for a custom built road car chassis.
There will be minimum external regulations to meet, ie basic road worthiness. But that's the fun of design, there isn't a step by step manual.
 
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Googling "tank-slapper" yields... even more amazingly useful stuff! Thanks Turbo, you now have a new fan!
 
jamesson said:
Surely enough rich lawyers buy bikes at this point that somebody may have demanded a formal spec by now?

In the UK the the legal requirements are the "Road Vehicles (Construction and Use) regulations". Curiously there is a separate "construction and use" law for pedal cycles in the UK, but apparently no document specific to motorcycles. Try searching for laws related to road traffic in your country.

However that may not help you much, because it will tell you what the regulations are and what test or inspection procedures are need to demonstrate compliance, but it won't tell you how to design something that meets the requirements. Actually that's how it should be - for example you demonstrate that a car design is crashworthy by doing a crash test, not be being forced to follow some prescribed design procedure which means you can't be innovative.
 
  • #10
jamesson said:
Googling "tank-slapper" yields... even more amazingly useful stuff! Thanks Turbo, you now have a new fan!
Thanks, again! I don't need a fan, but I'd love to save someone from a crash on a poorly-designed bike that only looks nice.
 
  • #11
Chris - just curious, what do you mean by system exactly?
 
  • #12
jamesson said:
Chris - just curious, what do you mean by system exactly?

A collection of parts and assemblies, to achieve a specific goal.
For example, a gearbox.

There whole concept will be done in 2D first, a basic outline of all components, shaft centres, ideas etc. It's just so much easier to scheme in a drafting package like AutoCAD.So for example with chassis design, I wouldn't start it Inventor. I'd scheme in AutoCAD first.
The idea of a chassis, is to just keep the cars components in the correct locations.

So you can plot the pickup points on your suspension (for example) in AutoCAD. Then you can draw lines representing the chassis members. this will give you an idea of how long each member is before you ever start modelling.
 
  • #13
Chris - how about this?

http://wikihelp.autodesk.com/Inventor/enu/2012/Help/0073-Autodesk73/0308-Parts308/0309-2D_sketc309/0320-Sketch_b320#GUID-C247DE64-FD88-435A-BA65-6A134B0EA511
 
  • #14
AutoCAD is still much, much better for a full system.

I've moaned about AutoCAD on here, but it's only now that I don't have it at work any more. I know how much I miss having that tool
 

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