Here is the big frame I mentioned in the other big bike thread that is going currently. It's a 67cm for a big dude. He has broken custom bikes and wanted something reliable and weight wasn't an issue. He is a strong guy and likes to climb but he is also an aggressive descender. We talked about disc brakes but he was firmly in the Ultegra camp so we stayed there. Modern DP brakes are awesome.

I used .9/.6/.9 on everything but the down tube (straight gauge) and stays. The head tube is a thick walled unit that I purchased in 1 meter lengths. We took in opinions from several people regarding the needs of the customer including what he had already been riding, what he had custom made and he also got a fit from a guy out his way in Cali.

We ended up coming up with something pretty normal. 73 seat, 73.5 head angle and a 670mm C/C square frame with 425 stays. I raised his BB a couple of MM due to long cranks.

Here is how it went. P.S. I also modded a vintage John Deere steering box for the Friday thread.

We started by being goofy for a few mins.


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Here is a bad photo of a nice tool. I can measure the wall thickness and locate the transitions. I forgot what the paint means on the end of the tube.

I made a collar to go between the 35mm down tube and the 31.6 seat post. I welded the OD and added a few random holes for plug welds.


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BB shell is vented. I grain it "with" on a belt sander with a scotchbrite belt to I can mark it with a caliper. Primitive, but I do many BB platforms.


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It's 10" long.


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I made the end of the top tube rectangle to fit against the seat tube. Remember, it's bigger than the seat tube.


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Here is how I do it.


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Mitre the seat tube end of the top tube first. It makes it easier to keep the tube indexed.


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Dinner time. More in an hour or so.,

Looking forward to this build!

"I grain it "with" on a belt sander with a scotchbrite belt to I can mark it with a caliper." No idea what this means, you're scuffing it with the belt?

If you're building the fork what steerer wall thickness will you use? Might as well ask what the ht wall thickness is, what is it?

thanks, Brian

Hole saw and not an end mill? I've been playing around with the bridgeports at work, trying to get a solid miter. I'm getting there- been taking small "bites" downward with an endmill and a lot of coolant, though I have yet to try a hole saw. I still haven't mitered anything but a 90*, so I'll need to figure out the rig for angles. I see you've adapted a... lathe chuck(?) to hit the angles for frame tubes. Cool.

And those scotchbrite belts and wheels are bloody AMAZING.

'sorry about that, I fell asleep. I mark the BB shell with scribe lines and center the tubes on the shell. To be able to see the lines that I make, I put sanding lines on the BB shell with a scotchbrite belt running the direction of the tube. Brian, We can use a fork with a 350mm steerer. I think the head tube is .083 or so. The frame isn't a triangle any more and that puts a big demand on the tube joints.

I have never been able to get a decent miter with a mill cutter (end mill). I buy nice hole saws an modify the teeth and true them if needed. If there is any danger of snagging (like another cut) or other weird stuff I set up the belt miter.

The tube holder is attached to a rotary table that has degrees, mins and seconds for setting angle. It has tube clamp blocks for all the normal tube sizes from 1-1/8 on up to 2" as well as several special shapes.

Dry erase lines to show transition locations.


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I use a ball hone to remove dirt from inside the tube. I welded a 18" extension on the hone and have it attached to a drill motor. I buy drill motors at tag sales and have many of them already set up with tools and remote power outlets at their dedicated locations.


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I remove burrs on the end of the tube further back than most people. My first welding job was welding cryogenic pressure vessels so I am very particular about burrs and dirt but I still needed to go further when prepping for brazing.


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Big


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Me welding.

The pringles can is filled with used electrodes. It weighs 10 lbs I would bet.


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I had to square the ends of the 25mm chain stays to get a good fit on the paragon hoodies.


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Dan's big bike by frankthewelder, on Flickr


Dan's big bike by frankthewelder, on Flickr


Dan's big bike by frankthewelder, on Flickr

Nice pics. What is the thinking on using the 1" cs, to help prevent(along with the beefy dt) lateral frame flex?

thanks, Brian

A frame this big reminds me of the "middle tube" Rivendell uses on some of their bigger frames. Helpful to reduce flex?

Looks like a FTW version of a "Big Leg Emma"

Yes, the stays are ........................................................long. It's only six lbs which is pretty good for this much metal. If I was to add a tube, it would be from the junction of the DT/HT to the ST/TT. I think adding a tube may be a better way to do a frame for a lighter rider but in my mind it would be making the front into triangles. My guy needs everything scaled up. I am not sure how the weight would compare but the chain stays I used about 30 grams heavier than Zona road stays so I guess we added about 150gm or more for rider power/weight on top of the tube length penalty. If I would have added a tube I would have paid the weight price but gained little torsional strength (IMHO).

If he wanted aluminum, he would have got seat tubes for chain stays LOL.

With long cranks and big feet, do you have to indent or bend the chainstays for heel clearance?

Love the "Roll of dimes" welds. You have the equipment to do a good job and the talent to do a great job.

Thanks. I enjoy welding quite a bit.


Yes, also a small dent for the chainring bolts on compact drive.

Not trying to hijack your thread, but check this guy out-



Have you ever seen this many ports?

I spent the day monday putting the covers on, by hand.



Then tuesday came around, and I brought this guy from home:



Awesome little doodad.

Artsy and/or fartsy:

You aren't trying to process weapons grade uranium with that thing - or are you?

Either that or you are an artisan cheese maker...

It's a time machine.

Who's with me?

That thing is beautiful!

Awesome bit of machine work there for sure. To follow Jonny's lead; Things that blow up others are a glut, but the world can always use one more cheese... now if it is also a time machine, one could send his cheese maker back 25 years and put you away some really great old cheese and hid it in your basement for you to discover.

To quote the late George Carlin from his anti-war days;

"The very existance of flame-throwers proves that some time, somewhere, someone
said to themselves; You know, I really want to set those people over there on fire, but
I'm just not close enough to get the job done!"

So it bolts onto the back of the Delorean, right?