This is a truly awesome and epic thread and although I cannot say it inspired me to start building frames (was inspired long ago) I started an apprenticeship with a master frame builder.
He prefers fillet brazed as he builds custom tandems and long tail touring bicycles with unique geometries but is also adept at building lugged frames.
Will be doing both as well as refitting, repairing, and customizing existing frames and was told my initial work was very good and my years spent as a bike mechanic and machinist are quite an aid when it comes to doing this.
Will surely be building custom racks and cages and have been working on some designs already.
The long term plan is for me to take over when he retires, even though he is already a decade past the age when most folks retire.
When building a frame like this, what are tpical tolernaces that you are working to? I mean for a high qulity precision ride, is being within a millimeter good enough? 2 or 3 millimeters? or do you need to be like within machining tolerances like say + or - .005? I am guessing by looking at the jig, a millimeter or 2 must be OK? Is being within this range generally considered precise in the frame building world? I guess manufactured frames are probably tighter?
How do you keep the rear wheel stay parallel so the rear wheel is perfectly true and in line with the center of the seat tube? Again is there a tolerance which is acceptable here?
thanks for any reply,
Chainstay length is another very tolerant value particularly if you build with horizontal drops.
Angles, particularly the headtube are best controlled to well less than 1/4 degree, which is trivial since the fixture really determines the finished angle of any joint.
For example, a 1/4 degree error on a 58cm frame will place the top of the seattube about 2.5mm from nominal, more than I'd be happy with.
I set the fixture with a large adjustable angle gauge and of course shoot for nominal.
Coplanarity of the main triangle is fairly crucial, I usually get a "perfect" result right out of the fixture due to the fact that I'm brazing subassemblies of headtube/downtube and BB shell/seattube and lastly the top tube.
However, if I needed to coldset, I'd shoot for less than 0.1mm measured over the length of the headtube. That works out to less than 0.04 degrees parallelism error headtube to seattube.
The jig I built fixtures the chainstays relative to the plane of the front triangle and a centerline thru the BB shell. If brazing results in a small lateral error I'll coldset the stays to less than a mm before brazing the
seatstays. Once the seatstays are brazed there's no hope of making vertical adjustments to the dropouts so that operation is critical. Vertical position of the upper surface if the dropout slot is held to less than 0.1mm error in symmetry.
A simple T gauge placed in the dropouts should place the center leg of the T at the center of the top of the seat tube.
In general, symmetry of frame features is more critical to ride quality than minor variation from nominal lengths and angles.
I'm building only for myself.
I don't really have time pressures to get a frame done in a few days. I can afford to go slow and get things exactly right, at least exact to my ability to measure an error.
wow, that answers exactly what I was wondering about. (Precisely)
thank you for replying, you are so kind to keep answering questions over the life of this thread.
I have been researching to see if it is feasible (cost effective) to build by own lugged frame. I was hoping to see if I could create a lighter bike than my current ride, (TSX/SLX Steel) which I restored, a far cry from what you have built here from scratch, I would probably copy the geometry.
I'm getting older and was hoping to make things lighter but the cost of today's lighter models is quite unaffordable for me. I am not sure if this is a good reason alone to build my own frame, but there are a number of other advantages. Since I have a ride now, I could take my time as you have.
I can't express what an astounding result you have achieved, so many others have tried to express this, I'll just pile on.
thank you again,
Read the whole thread and like everybody else, I was amazed. Both at your ability as a framebuilder and your kindness in documenting it and answering all the questions.
I'm in college and I'm just starting framebuilding as a hobby. I have been looking at different home built jigs and I like your design the best. Do you have any more pictures or details of the jig other than what you shared within this thread?
Am I the only one who can't see the pics?
Nevermind. Upgraded to Prem. Membership and now they show up. Awesome!
A real man's hobby. Good job. I am interested in building my own bike someday, but it will be way way down the road cause I got to get through engineering school first. Got to get a garage and a bunch of special tools.
Say... would it be much more difficult to make carbon fiber parts? I don't know about homemade carbon frames though... *crack*
Sitting here with the laptop and read this thread twice. I am almost speechless.
My eyes were popped out so much my wife thought I was looking at naughty websites.
Yep, THAT Ira
I just read the whole thread. Many of my questions were asked and answered along the way. Thanks!
thank you, sir!
for your generosity for showing (us) how's it done.it's really inspired me more and i wanna learn to built my own frame,but the thing is i'm felt too old to learn (sigh)...i'm admired your crafmanship and your kind heart personality!!
i'm not a roadies,but i'm pretend to be just so i can fit in here!
Beautiful work, I hope that you are treated with the respect that you deserve. Just picked up a trashed bike that is beyond repair, will use this as a start for lugs and tubes.
Totaly cheap wieght weenie. Totaly cheap bike snob. But I love Italian hand made stuff. 84' Ciocc, 85' Raleigh Super Course, 96' Sakae Litage, 2000 Lemond Maillot Jaune,
2010 Nashbar SRAM RED, 86', 87', 89' Ironmen, 96' Schwinn Super Sport, 79' Shogun 1500, and ten projects.
Very nice thread and gave me some more understanding on building a lugged frame. But could you go over how the seat stays attach to the seat lug a little for me?
There's a lot of variety in attaching seat stays -- many builders see it as sort of a "signature."
If the stays are attached to the sides of the lug, it's simply a matter of building a fillet of brass or silver under the stay. I usually file a shallow groove in the side of the lug prior to brazing to help hold the stay in place and provide a little more surface area for the joint, but it isn't strictly necessary.
There are plenty of variations on this with different degrees of wrapover, the shape of the stay ends, and so on.
"Fastback" attachment where the stays are attached to the back of the lug requires the stays to be mitered to fit the lug. The seat clamp may or may not be integral with this attachment.
Last edited by JohnDThompson; 05-03-11 at 11:37 AM.
Take a look at post #82 for pics and explanation.
As you can see, the profile cut into the top of each stay allows it to fit against the seatlug, then it's just a matter of brazing a fillet at the joint.
Didn't see anything in post 82 that dealt with attaching the seat stays to the top seat tube lug, unless the images wouldn't load.
But the above post did help me out.
Truely inspirational work of art
Thank you for the educational thread.
Do you think its possible to build a frame without jigs? I am very interested in building one myself and have been researching around, watching videos of how homemade bikes are done...... and it seems possible. But I would like to hear it from you. Your insight to this would be most helpful.....
Thanks a million,
I've built a few that way, and it can be done with little more than a good bench vise, a box of files and a torch.
That said, I do think building in fixtures is easier, at least for the rear triangle and fork.
Can't see the pictures