Topic: Aftermarket frame - group purchase

[napoleonb]

DOM is just a fabrication method for tubing, it has nothing to do with the material properties of the basic material.
(that being said each fabrication method alters the basic materials a little or lot depending on the amount of stretch)
Simply put the material has uniform properties and no welds on DOM so it behaves a bit better, its also stretched a little improving grain structure, hardness and tensile strength at the surface.

The discussion of which frame to choose or how much it should cost doesn't interest me much but i'm planning on doing a CR110 frame build myself in a couple of years.
Being a mechanical engineer by profession I really would like to alter the diameter of a single tube from point to point as the CR110/RC166 and name a few frames had.
In effect making the tubing conical distributes the material to a larger/wider area further from the center bending line which improves the moment of resistance against bending (not sure if this translates as well in English as I hope it will). Designing a custom frame will let you do the same with changing the amount and position of tubing/bracing.

Does anybody know of a firm which can stretch tubing equally from 20 to say 30mm over a length of 200mm?

   

[MessnerMoto]

Yoss is correct. The major goal of a frame/chassis design is to make it as rigid as possible and as light as possible.... That being said... Young's modulus of elasticity is the major parameter to look at. Actually CrMo steel has several percent higher modules of elasticity compared usual steel. But is it worth it thats for discussion... If you want to squeeze every drop of performance than it is worth it.... but the cost goes higher

Changing to lets say aluminum will get you nowhere if you don't increase diameters of tubing, change geometry etc... Specific weight of aluminum is around 2.7 and for steel it is 7.8... Young's modulus for Al is around 70GPa and for steel is around 200GPa. Metric units...

So 7.8/2.7 = 2.89 and 200/70 = 2.86.... and that means Al tube of same size as steel tube is around 3 times lighter than steel one but also 3 times less rigid/stiff then steel one....

One of the ways to make space frame more rigid and lighter is to increase diameters of tubing and lower wall thickness. 

The bending stiffness and strength are proportional to the section modulus of the tube, which for a pipe is its second area moment divided by its radius or

S=Pi/32 * (Dˆ4−dˆ4)/D where D is outer diameter and d is inner

If it's a thin walled tube w=(D−d)/2 is much less than D than

S ≈ πˆ4 * Dˆ2 * w

for thin-walled tubes, the strength of the tube increases much faster with D (square relationship) than with wall thickness(linear relationship). Doubling the diameter will give four times the strength. Doubling the thickness will only double the strength. Both methods will double the weight.


Personally for me I would make frame from Al 6061/6081 or 316 steel just because I like raw metal without paint. Of corse geometries of Al and steel frame need to be different

... I once read from one Tour the France bicycle frame manufacturer that their Steel and Al frames weight completely the same for same stiffness... cant find the link now...

///////////////////////////////

and this is all of the topic

more pictures of cb750 frames... second one is moto martin

[napoleonb]

DOM is just a fabrication method for tubing, it has nothing to do with the material properties of the basic material.
(that being said each fabrication method alters the basic materials a little or lot depending on the amount of stretch)
Simply put the material has uniform properties and no welds on DOM so it behaves a bit better, its also stretched a little improving grain structure, hardness and tensile strength at the surface.Completely agree.

Does anybody know of a firm which can stretch tubing equally from 20 to say 30mm over a length of 200mm? I've only found companies that sell very thin wall tubing for bicycles where its swaged or conical in its length. Not sure you'd want 0.035 walled tubing? I personally don't know of a service company here in the states where you can source this tubing, nor have it produce in small lots for a consumer project.

Would making your frame from Ti tubing be a consideration? There are sources here for reasonable pricing on straight wall, straight length tubes. Perhaps it as a material could resolve your design goal?

I'm trying to mimic the external dimensions as close as I can, its not really a performance quest I'm after.
Though I'm going to calculate wall thickness/material tensile strength to determine which material and dimensions to use.
Ideally I would like to make a run of 2 race and 2 street bike frames which differ only ever so slightly.

[turboguzzi]

Cal, if hardness was important for frames, nobody would be using aluminum

Ti, not so great for frames, half the Young modulus of steel, i.e. you'd need pretty hefty sections every where to be equally stiff... that's why you leave extra squish clearance with Ti rods, they stretch more
in any case, doable but at that point advantage over steel is low, not to mention the pain to cut and weld Ti.

[Sam Green Racing]

Hi Ric, due to my health problems, we've not spoken in quite a while, I take it you are well and still endurance racing.
It's just a thought but why did you choose the Egli, Seeley and Moto Martin frames ?
There was another frame that Honda themselves commissioned to be made and they went on to lots of race wins and several World Endurance Championships. Have Egli, Seeley and Moto Martin won any World Championships ?

Sam.

[eli]

Ok so who build a Rickman copy for 2500 , please let us know.
 

Well, in central europe, it would be easy. Just buy this one.

https://www.ebay.de/itm/Rickman-Replica-Cafe-Racer-Rahmen-Chassis-Kit-Honda-Kawasaki-NEU/222569750966?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

already nickel plated and ready to go.

I think that Terry Weedy makes them, but thats not confirmed:

http://www.terryweedy.com/

I'm sure that you can get a much better quote if you order directly from Terry than buy it from the german reseller.

I was told (by Axl/satanic mechanic a long time ago) that the Rickman frame is almost as heavy as the stock one and doesn't handle as well as the Seeley. I'm very much interested in building my own seeley-clones, as I have the original here. Already started to build a jig, now going into the TIG-brazing, so I'm reading this thread with interest.
eli

[livefast_dieold]

Ok so who build a Rickman copy for 2500 , please let us know.
 

Well, in central europe, it would be easy. Just buy this one.

https://www.ebay.de/itm/Rickman-Replica-Cafe-Racer-Rahmen-Chassis-Kit-Honda-Kawasaki-NEU/222569750966?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

already nickel plated and ready to go.

I think that Terry Weedy makes them, but thats not confirmed:

http://www.terryweedy.com/

I'm sure that you can get a much better quote if you order directly from Terry than buy it from the german reseller.

I was told (by Axl/satanic mechanic a long time ago) that the Rickman frame is almost as heavy as the stock one and doesn't handle as well as the Seeley. I'm very much interested in building my own seeley-clones, as I have the original here. Already started to build a jig, now going into the TIG-brazing, so I'm reading this thread with interest.
eli

I saw you Seeley development! Weel if you are going to build a copy why don't you open a building thread somewhere?
I will also be interested in buying one, if you decide to build 2 copies :-)

[scottly]

I was told (by Axl/satanic mechanic a long time ago) that the Rickman frame .. doesn't handle as well as the Seeley.

Likely due to the Rickman swing-arm bushings being rubber?
Here is an interesting Reynolds document:
 

[simon#42]

they were both good frames in the day but neither handle well by modern standards . a classic looking frame with more modern geometry would be much better than a copy of a 50 year old design .

[MRieck]

So.....who's building the frames and how much?

[MessnerMoto]

Nobody for around 300$ 

[eli]

Ok so who build a Rickman copy for 2500 , please let us know.
 

Well, in central europe, it would be easy. Just buy this one.

https://www.ebay.de/itm/Rickman-Replica-Cafe-Racer-Rahmen-Chassis-Kit-Honda-Kawasaki-NEU/222569750966?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

already nickel plated and ready to go.

I think that Terry Weedy makes them, but thats not confirmed:

http://www.terryweedy.com/

I'm sure that you can get a much better quote if you order directly from Terry than buy it from the german reseller.

I was told (by Axl/satanic mechanic a long time ago) that the Rickman frame is almost as heavy as the stock one and doesn't handle as well as the Seeley. I'm very much interested in building my own seeley-clones, as I have the original here. Already started to build a jig, now going into the TIG-brazing, so I'm reading this thread with interest.
eli

I saw you Seeley development! Weel if you are going to build a copy why don't you open a building thread somewhere?
I will also be interested in buying one, if you decide to build 2 copies :-)

  You DID see that I need like eons for everything I do? When the jig is finshed, I will start with a custom aluminum e-bike frame (the jig is quite universal). Then I will get some CroMo Tubes and try TIG-brazing. If that works, I will eventually start with a Seeley-copy. With my schedule, that will be in 2020 
So, look out for that thread in two years!
eli

[MessnerMoto]

Because nobody is building the frame currently. I will still the thread

This is what I imagined for my dream frame for CB750.... It is designed for monoshock... This is version 0.1 there will be more iterations....

I had 3 main design goals

1. Keep the stock look.

 I really think that the overall beauty of cb750 is greatly associated with look of the stock frame. The straight line of the frame that goes from neck to tail of the bike defines the look of the CB750... Also I really like space-frame tubing feel. So a lot of tubing in my design

2. Be lighter

All the metal in the pictures (excluding exhaust ) weights 5kg because this is all Alu tubing... 25mmx1.5mm with some 15mm plates

3. Be stiff

there is a lot of triangulation because Al is 3 times less stiff then steel. The problem is to bypass the engine, exhaust and carbs with cross-members...

I have also the model of OEM frame. When I find some time I will do the FEA analysis and compare the two....

I can see the problem in welding it together because of all connections and a lot of heat that will go in to the metal... Also it needs to be heat treated after...

The jig.... I can make one fast for this, cheaply, using waterjet....

This is not optimal design for racing but my first goal is the look....

[gschuld]

Mirko,

I’m always impressed with your creativity and CAD type skills.  I wouldn’t presume to be able to offer you any hard engineering feedback, but there is a logostical point of interest aid like to point out.  Your design will require dropping your engine out the bottom for any work that requires the cam cover to come off. 

This is why the frame kits are so popular with stock frames.  As it allows direct access to the top of the engine and allows enough room for anything from cam adjustments to full on cylinder/piston removal.  If designing a high performance frame from scratch, not designing in access to the top end without separating the engine from the frame is a drawback you’ll have to accept.

George

[MessnerMoto]

Yep... aware of that but taking out the engine in this design is job of 1h max..You can just drop it down... . and you dont need to actually take the engine out you need to pivot the frame around swingarm pivot. Like it is done on CBX

On my current bike I made a special frame kit.. it is special in the sense you cant see from side of the bike where the tubing is cut.

http://forums.sohc4.net/index.php/topic,149894.msg1869266.html#msg1869266

But to disconnect all the wiring etc is more then 1h in my current setup

... always some compromises

[slikwilli420]

I love the design but its still pretty busy. You said it yourself, the appeal is stock-looking frames, which is why the Rickman and Seeley are so attractive, yet have advantages over stock.

Aluminum is tricky and presents a host of flexibility issues that are not ideal, not to mention that a jig to hold it while heat treating would be cost prohibitive in itself. That frame looks extremely complicated to build with all of the joints between tubes. Im not saying you should steal a design but much of the work has been done in classic frames for our bikes. Take elements from those and make something your own. It will be difficult to improve on a design and still keep a classic look.

[754]

He did mention 1.5 mm  wall, same as Stock.
I think if you can tip the motor and access top  that would be good enough.

[Medyo Bastos]

I think if you can tip the motor and access top  that would be good enough.

I agree.




Sent from my iPhone using Tapatalk

[turboguzzi]

mirko, look at it form a business side...
for classic racing in most countries you cant "invent a frame", it has to be period. no business.
for road bikes, in most european countries it'd be a nightmare to run legally (TUV, etc...) USA might be easier, not so sure. 
the only way would be then what Sanctuary are doing, i.e. become a legal manufacture and sell complete bikes. their superb frames require (like yours) all custom body parts, so it makes sense in any case. but you'd need VERY deep pockets to go into that...
the beauty of the sanctuary frame is of course that form the outside bike looks quite stock...

[MessnerMoto]

This is a frame for me not for selling it. Built according to my needs and preferences. I stated that in my post

Lets just say it is a grey zone.... for riding this frame on streets.

[MessnerMoto]

He did mention 1.5 mm  wall, same as Stock.
I think if you can tip the motor and access top  that would be good enough.

1.5mm is 0.059. Stock is 0.063. He would need to bump to 1.8mm to match stock. The difference in weight between the wall size is 0.21#/ft for 1.5mm vs 0.22#/ft for 1.8mm.

Cal maybe you are correct. I would probably need to bump to 2.0mm wall thickness... It will probably take me to 7kg of weight.... before optimization....

The goal is to offset less stiff al with full triangulation.... but FEA will tell if 25x2.0mm is good or if triangulation is good   

Also there will be some bracing to address front engine mounting point

[754]

 The heat treating , raises the price and involves some time, like a week or more turnaround. Probably same as paint or plating.
 A local guy built A few aluminum frames,  but no longer does. One big concern was buyers wanting to add or modify a frame after the  sale. His reasoning was no matter who did the work , if it failed, it still comes back to his name.

Also In hestvtreat things move sround a bit, so you may want to finish neckbores after treatment.  And expect to maybe have to tweak the frame a bit..

[scottly]

Any precision work is always done after welding or heat treat.

[Captain]

 It might be of interest but I'm underway building a new frame for our Pre 82 DOHC Superbike.
 The point of difference.........."Titanium" 
 Not for the faint hearted and all the analyse has been done and we will have a frame to perform at least equal to our current.

 Captain

[turboguzzi]

Captain, you never fail to impress!

Mirko, ok, must have missed thats it's a single copy.

Nevertheless, where are you going to put a decent volume of fuel with that spine taking up all the place?