Author Topic: Dropouts design (Read 5713 times)

PiR products · « **on:** August 23, 2011, 04:42:33 PM »

Hello,

I have a special request...

I'm working on new dropouts for PiR frames.
The shape of the dropouts is determined and will look like the following picture :

I would like to sollicitate your help/imagination :

In order to make them ligther, I need to add some holes in it.
The area of the dropouts where some material can be remove is illustrated by the blue surface in the following picture :

To illustrate what I would like to obtain, the following picture is an example :

Because the dropouts are laser cutted, the shape can be as complex as you want...
But they also have to be strong enough, so it's not as easy as you can imagine...

There's nothing to win, just contribute (maybe) to help to design a dropout.

You can download the following 1:1 scale PDF file of the dropouts, in order to help you...

Thank you

kabirun · « **Reply #1 on:** August 23, 2011, 05:00:07 PM »

I think too many holes in a dropout or for the same purposein a headtube , make a frame look funny, at least for me. whatever you decide just keep it on the sober side.

cheers

Alex

pwh4130 · « **Reply #2 on:** August 23, 2011, 05:24:38 PM »

I think those holes are going to weaken the dropout incredibly. Maybe machining out but not all the way through?

2flat2furious · « **Reply #3 on:** August 23, 2011, 06:57:56 PM »

I wouldn't bring them all the way to the end. I've cracked dropouts near the outside of the circles because of the drilling. When you start looking for weight reduction there you are weakening the rear end of the frame by a really really significant amount.

PiR products · « **Reply #4 on:** August 23, 2011, 08:03:53 PM »

Quote from: kabirun on August 23, 2011, 05:00:07 PM

I think too many holes in a dropout or for the same purposein a headtube , make a frame look funny, at least for me. whatever you decide just keep it on the sober side.

I understand your point of view (BTW it's funny to read that from the futur owner of a Gamma frame

)
On the other side, when the pegs are installed, most of the holes are hidden...

Quote

I think those holes are going to weaken the dropout incredibly. Maybe machining out but not all the way through?

Yes it's true that a machining would be the best solution, but it adds cost and time.
My example shown is certainly too weak, it was just to illustrate...
Basicaly, those new dropouts are thougth to make the building process easier, so I don't want to add any operation to the laser cutting.

Quote

I wouldn't bring them all the way to the end. I've cracked dropouts near the outside of the circles because of the drilling. When you start looking for weight reduction there you are weakening the rear end of the frame by a really really significant amount.

Fortunately, until now, there wasn't any problem of bent dropouts on PiR frames.
The thickness of my dropouts are already thicker than most of the other brands.
I'm totally aware of the weakening that badly located holes create.
My only purpose was to see if people here would suggest an interesting hole patern.
The difficult thing is that the loads appllied to the dropouts are complex to simulate...

I don't want this topic to become a debat concerning the weakening of adding holes.
I just would like that someone shows something nice, strong and functionnal.

stuntnuts · « **Reply #5 on:** August 23, 2011, 08:17:37 PM »

Aren't you the frame designer, therefore isn't it your responsibility to determine where the holes in the swiss cheese dropouts belong?

A Structural Engineer doesn't ask the guy doing the hardwood flooring install where the main support beams should be located, does he?

efxman · « **Reply #6 on:** August 23, 2011, 08:47:56 PM »

I say no holes, is it saving that much weight, no it really isnt. Keep it simple and functional and most of all so it doesnt bend or break. As for asking our opinion I see nothing wrong with that. Dont we all wish that manufacturers asked us want we thought would be a good idea. They can always refuse them but at least you feel like you are part of the input and you may very well come up with something innovative.

Andrew Tarrant · « **Reply #7 on:** August 23, 2011, 09:11:33 PM »

how much weight do you lose exactly? I would have thought thats where youd want the weight most

h410G3n · « **Reply #8 on:** August 23, 2011, 09:49:32 PM »

Quote from: stuntnuts on August 23, 2011, 08:17:37 PM

Aren't you the frame designer, therefore isn't it your responsibility to determine where the holes in the swiss cheese dropouts belong?

A Structural Engineer doesn't ask the guy doing the hardwood flooring install where the main support beams should be located, does he?

So it's your responsibility for flaming the people asking for inputs on this forum? Howdy officer.

PiR products · « **Reply #9 on:** August 24, 2011, 03:59:53 AM »

Quote from: stuntnuts on August 23, 2011, 08:17:37 PM

Aren't you the frame designer, therefore isn't it your responsibility to determine where the holes in the swiss cheese dropouts belong?

A Structural Engineer doesn't ask the guy doing the hardwood flooring install where the main support beams should be located, does he?

Cinserely your message left me speechless...because it's hard for me to undertsand people who think like you.

But, I'll answer you for the first and last time.
There's so much things you seem to not understand that I don't really know where to begin...

You seem to be a narrow minded person who obviously don't know how a structural engineer works.
Even if yourself are a structural engineer I don't care, it doesn't proove you are making a good job.

A structural designer belongs to a team. It means that in order to offer the best solution,
he will ask to this team or anyone else any informations which would help or advice
him in his design process.

Is that so bad to ask to the user of a product how they would imagine this product ?
I think you know the answer...

Please read my first message (even if English is my third language, I think it was enough understandable).
I never said that I will use a "submitted sketch" of a GF user :

Quote from: PiR products on August 23, 2011, 04:42:33 PM

just contribute (maybe) to help to design a dropout

The fact is that asking someone to give his opinion is always beneficial, not obviously usefull but certainly interesting.
It's what I did in this topic.

I could write a book concerning the problematic of a dropout, from an ergonomic, functionnal, aesthetic, physical or weldable point of view.

There is often several solutions to a same problematic.
It's not because you remove material that you make a part weaker.
Most of people think so, but they are soo wrong.
Removing material can make a part become stronger, stiffer, more ellastic and more durable.

To resume, you can have different hole patterns and have the same resistance.

I'm a frame designer and you don't have to tell me what I have or don't have to do.

In 3 years, only 1 PiR frames had some cracks because the rider wanted something too light (0.028" tubing thickness for the rear).

Quote

how much weight do you lose exactly?

Not a lot, something like 10 g/dropout, but it's more the 22 % of the weight saved that is important.

stuntnuts · « **Reply #10 on:** August 24, 2011, 05:13:01 AM »

Once the flooring guys get to the job site, the columns, beams, joists, and sub-floor have already been designed and installed. Therefore, their input is worthless and of no concern to the design team. I apologize if my chosen analogy got lost in translation or simply went over your head.

You want input, here's mine.......stop trying so hard. You've got a self-proclaimed good track record for producing frames that don't break, so why stop now? Keep it simple. Just because you have the technology to laser-cut anything your heart desires into your dropouts doesn't mean it's necessarily a good idea....stop flossin'. The weight savings is negligible at best and certainly not worth the sacrificing of strength in a notoriously weak area of a bicycle frame. But hey, it's your company.....do what you think is best. Good luck in your endeavors to create invisible dropouts.

B-random Fantom · « **Reply #11 on:** August 24, 2011, 05:42:53 AM »

I would like to see a flatland frame with Sunday style dropouts. The ones that are 8mm thick because they consist of two machined pieces joined together so they are both light and strong and include an internal set-screw chain tensioner. That would be the best in my opinion.

byke · « **Reply #12 on:** August 24, 2011, 09:45:55 AM »

I am just rushing out for a haircut, so have only spent 3 minutes on the drawing .... so please excuse.
(And no styling has been done .... just concept to show the basic idea)

I think it should only feature 2 holes where the tubes meet.
And the rest of the dropout should be whole, but with cut indications and lines to follow if a rider doesnt want a long dropout.

oldmanjoe · « **Reply #13 on:** August 24, 2011, 04:56:54 PM »

In my other life, I ride a Standard 125r. I like the dropouts on this bike because of the logo they cut out.

So I would steal that idea and just use your logo.

On a flatland bike, I wouldn't remove any more material than the logo though.

Ideally, you would want it visible with a peg installed, which could be an issue.

PiR products · « **Reply #14 on:** August 25, 2011, 02:12:15 PM »

Quote

Once the flooring guys get to the job site, the columns, beams, joists, and sub-floor have already been designed and installed. Therefore, their input is worthless and of no concern to the design team. I apologize if my chosen analogy got lost in translation or simply went over your head.

You want input, here's mine.......stop trying so hard. You've got a self-proclaimed good track record for producing frames that don't break, so why stop now? Keep it simple. Just because you have the technology to laser-cut anything your heart desires into your dropouts doesn't mean it's necessarily a good idea....stop flossin'. The weight savings is negligible at best and certainly not worth the sacrificing of strength in a notoriously weak area of a bicycle frame. But hey, it's your company.....do what you think is best. Good luck in your endeavors to create invisible dropouts.

Yes, sorry for the "hard" answer, I'm often too much susceptible.

Quote

I would like to see a flatland frame with Sunday style dropouts. The ones that are 8mm thick because they consist of two machined pieces joined together so they are both light and strong and include an internal set-screw chain tensioner. That would be the best in my opinion.

Yep this technology is very nice and I really would like to have those king of dropouts on my frame (with a different shape), but I really don't know how/where it would be possible to make them.

Quote

I think it should only feature 2 holes where the tubes meet.
And the rest of the dropout should be whole, but with cut indications and lines to follow if a rider doesnt want a long dropout.

Thanks Mark for your contribution, those holes are nice and the cut indication is a good idea.

Quote

In my other life, I ride a Standard 125r. I like the dropouts on this bike because of the logo they cut out.

So I would steal that idea and just use your logo.

I already had the (very good) idea to have the logo on the dropouts. I'm not sure that with my logo, it will be "laser cut friendly", because of the very small cut outs, but I'll give it a try and see what happen.

Anyway, thanks to the people who contribute to this topic and gave their input.

According to what has been said, here's a "modified" dropout.

Feel free to give your opinion...

Author Topic: Dropouts design (Read 5713 times)

PiR products

Dropouts design

kabirun

Re: Dropouts design

pwh4130

Re: Dropouts design

2flat2furious

Re: Dropouts design

PiR products

Re: Dropouts design

stuntnuts

Re: Dropouts design

efxman

Re: Dropouts design

Andrew Tarrant

Re: Dropouts design

h410G3n

Re: Dropouts design

PiR products

Re: Dropouts design

stuntnuts

Re: Dropouts design

B-random Fantom

Re: Dropouts design

byke

Re: Dropouts design

oldmanjoe

Re: Dropouts design

PiR products

Re: Dropouts design