custom frame building

[CScriba]

Does anyone have any experience or any knowledge at all on bike geometry and sizing , what tubing to use, special tools needed?

 

me and my dad want to try building a time trial bike (for sh*tzand giggles) , but im struggling to find info on the process, dfferent angles and geometries  etc.

 

want to achieve something like this (with some changes):

 

 

[Johan Bornman]

Building your own frame is an interesting project.

Don't worry too much about angles and all that. You already have the angles, you just haven't measured them yet. They are right there in the photo your posted. Print the photo, get a protractor and get cracking.

 

You know the size of a Zipp wheel and therefore you have a scale to work to.

 

That particular bike is built with TIG-welded tubes. Tube welding of that type is a very skilled exercise and I advise you to rather have someone else do the welding if you're not a pipe welder.

 

I built a frame but silver-soldered it. Silver solder is a low-temperature process and helps a beginner to avoid overheating the tubes.

 

Don't fuss too much about the type of steel either. Take what you can get at the time. Reynolds and Columbus still make bike tubes. Mine was built from lugs but yours will be mitered and welded - a bit more difficult.

 

There are some Youtube videos on framebuilding and mitering. Have a look.

 

You can buy finished drop-outs from the likes of Columbus and Cinelli. These dramatically reduce the detail work you have to do.

 

In order to have the frame straight in all planes, you'll have to build a jig to hold the loose tubes during welding. Don't skimp on this. I had a steel plate - about 8mm thick and as big as a frame. I mounted this at a 45 degree angle on some tressles also made for the purpose and then welded bits and pieces on there to guide and secure the frame elements. The jig took as long to make as it took to make the frame, but it was well worth it.

 

I also suggest that you practice your mitres on pieces of mild steel pipe. Butted Chrome moly steel is very expenisive and not for practicing. Years ago my tubeset was something like R6 000. I think that was when the Rand was R14 to the dollar. It may be less now.

 

Speaking of money, don't for a minute think this will cost you less than a bespoke frame. It will cost your double or more.

 

Enjoy, it is a nice project. 

 

 

 

 

[Jules]

That bike is HOT.

[CScriba]

Johan: Do you maybe have  link or a place where one can buy the tubing?

is it a special kind or basically just stainless steel....trying to place how much it would cost me

 

thanks

 

[javadude]

Theres a company in the UK that sells a starter kit for frame builders. Will get you the link. There is also a frame builders forum where you can ask these kind of questions.

[javadude]

http://www.framebuilding.com/

 

[CScriba]

thanks velo

[javadude]

No problem. That forum is www.frameforum.com, but i can't get in there, seems like the International bandwidth is acting up again.

 

I told my wife that this is what I want for my birthday. Go check it out, looks like fun:

 

http://www.daveyatescycles.co.uk/courses.htm

 

[CScriba]

got a little prelim scetch going here, tell me what you think 

 

 

 

[HeartCoppi]

If you choose to assemble an aluminium bike frame...

Please dont use local extrusions from companies that present products for the aluminium door and window industry. These extrusions are not of a suitable grade for a frame.

You may notice that most aluminium frames are built using a six series aluminium. For interest sake the grades of alu are ranked from 1 to 7. 1 being the lowest grade and 7 being military and aviation grades. Also the physical and mechanical properties of the aluminium improves on a higher grade.

 In this case weldability is of extreme importance.

The higher the grade the "cleaner" the aluminium. Therefore also less weld "impurities" jeopardising the weld quality and strength.

Insist on 6 series tubing from specialised local shops that deal in non- ferous articles/products.

Use lower grades only for prototype and practise but do not ride!! I fear poor and"dirty" weld quality will put at risk of weld failure. 

[HeartCoppi]

I forgot to ask if you will only be making a frame oR will you be making a frame and a fork? 

In your construction there will be diameter critical areas. BB, head tube, fork these may be difficult to acquire if you have very exact expectations.

You may have to machine a significant amount from solid bar of 6 series eg 6082 T651 or 7 series eg 7075 T651. The 7 series has a higher tensile value and you could even design lighter sections.

 

Then theres the issue of TIG/WIG welding. Wow welding is a heck a lot of fun but it takes a lot of time and skill to have the correct aesthetic appearnce (or ripples) in the weld seam. You also need correct settings to ensure good weld penetration and good preperation to ensure no weld impurities or pitting. Do try to use a certified aircraft welder for the sake of safety. Maybe somebody can test your welds. At least with a dye penetration test as a minimum. More advanced would be x-ray.

 

Remember welding involves heat ( alot of heat) to melt the base material. So there is alot of expansion and contraction. Distortion is inevitable. therfore you have been well advised by Johan about a jig table to hold everything in place VERY securely to 'choke' distortion. This is costly but essential. You must invest in a strong bed and several versatile or adjustable and strong clamps. These must also be tube friendly at the same time.   

 

The appropriate filler wires should be in the area of a 5083 preferably and not 5356.

 

 

Use this mindset as you proceed:

I look at the picture of this beautiful bike that you posted and think:

(1) if the head tube and the seat tube are not absolutely parallel, you will feel  it. (2) if the BB is not perpendicular, you will feel it (3) if the seat clamp is not welded straight, it will p#ss u off....etc.

 

No jig ...no go. So prep is the key to position, quality the key to safety.

tarboy2009-08-28 15:59:25

[CScriba]

 

im already in he process of building a jig ( my dad used to build frames for himself in the oldern days)  , if i do it  aluminium il be sure to get the good quality stuff, i dont want to end up breaking my neck cause of bad alu....on the welding side, i know someone that cold do the alu welding that has alot of professional experience, but if i do it in steel ill be using metering and silver soldering which my dad has worked with..

 

im quite fussy about little things so ill be sure to do everything 100% properly

 

hanks for all that info though tarboy, will help me loads!!

 

eclipse2009-08-29 03:59:00

[EigerSA]

For the steel, you need chromoly 4130. Speak to the guys that are involved in motorsport racing or home-built aircraft. I built a frame a few years ago (road bike) and am busy planning a mtb build. Keep us up to date and add some photos... good luck with the build!

[Flowta]

http://www.frameforum.org/newportal/index.php

 

 

 

[gummibear]

Goodluck i will be watching this to see how it turns out.I would love a steel bike.

[CScriba]

i must just somehow get this tubing .... anyone know places to get in gauteng (pretoria, open to anything though)??  any aircraft or motor racing places??

 

1 last Q: wich one would be better , TIG welding or silver soldering?