Built A Frame Today

[daveyjones97]

thanks guys, ive had mostly bad experiences as a noob commenting in other peoples threads before, as i say i dont know the forum etiquette unwritten rules, dont mean to tread on toes and all that.
anyways here are the photobucket links to the mtbmx i built. i do have a lightly cosmetic damaged suspension bike i bought NEW from tesco (like wall mart) for £19.95!!!! its the suspension bike that will be getting ebiked at some point, no pics of that. heres the links:
http://i1096.photobucket.com/albums/g325/daveyjones97/045.jpg
adjusting seat angle in relation to head angle
http://i1096.photobucket.com/albums/g325/daveyjones97/270720112039.jpg
originally 1 frame all silver 1 all black
http://i1096.photobucket.com/albums/g325/daveyjones97/160720112006-1.jpg
finished frame, toptube welds ground down to check penetration and because the tube i extended it with (2 in to 23 in total) was same diameter
http://i1096.photobucket.com/albums/g325/daveyjones97/070820112087.jpg
luck and judgement coming together for once. chainstays are same length as a haro sport 20inch bmx
http://i1096.photobucket.com/albums/g325/daveyjones97/161020112292.jpg
http://i1096.photobucket.com/albums/g325/daveyjones97/DSCN4955.jpg
http://i1096.photobucket.com/albums/g325/daveyjones97/DSCN4956.jpg
http://i1096.photobucket.com/albums/g325/daveyjones97/DSCN4959.jpg
lol, wheelie flip!

 

[daveyjones97]

the geometry is if i remember right: 75deg head angle, 73 seat angle, 23 in top tube, bottom bracket on wheel axle line rather than above it like a bmx or below like an mtb, chainstays same as a haro sport (cant remember off top of my head) 1ish inch fork rake and 49ish inch wheelbase 24inch wheels. i cant find the measurements so thats from memory. anyone who knows anything about bikes will see that geometry will not make for a relaxed 30mph cruise!
its a muckabout stunt jump bike

 

[pelle242]

For bicycle hacking www.atomiczombie.com has lots of good info, mostly bents but still good reading.

 

[Gordo]

(I'm not sure if it's hot enough for brazing anyway).

With the right torch head you can easily braze with straight LPG, or the hotter flame from MAPP, with the same head. You do not need a second bottle with oxygen to stick bicycles together. With a few firebricks, you can build a little "oven" around your work and conserve the heat for the job instead of heating the world.

 

[etard]

HAHA , nicely done Davy! I didn't put any effort into figuring out head angle or chainstay length, I figure I'll get it all finished and throw some components on there and see how she rides. I just know I wanted it stretched and the stock headtube angle wasn't too bad. It's gonna be a cargo-cruiser anyway, not meant for speed. I like your shop too. I'm lucky to live in Southern California where in the middle of December the whole backyard is my shop.... In short sleeves no doubt!

Well, I figured out how the dropouts are gonna go and I'm quite pleased how it turned out. Now all I need to do is weld it all together.

Rounded the rear edge, did some lightening and "speed" groove.

I should have this finished today, I also have a neat idea to "daisy" this baby up... How about a dog basket that straddles the top tube?

 

[etard]

All done! Well, no, there's lots left to do, like paint for one. Dropouts ended up being about 155mm, weight without forks is 12 lbs.

 

[geetarboy]

Unique design,Etard. You sure can do alot more with a torch than an arc welder. If you need to tweak the frame, you can heat it up and twist it a little. Working w/ metal is fun.

 

[Gordo]

I like the neat way you bent the seat-stays into a rack. The dropout clamps are also 1st class.
With a little less heat or more localized heat, you will get the brass just where it is needed, to form a strong joint. No need to paint the frame with brass or have to grind the results off. Most of the strength of a braze is right at the joint of the 2 pieces of metal or as with your sleeve joints, in between the sleeve. Now you have mastered brass, maybe buy a couple of SilPhos rods and see how easy it is to use. http://sra-solder.com/section.php/3/1
Not as strong a joint as straight brass, but sucks in better on socket joints.
Always braze from the bottom of the joint, up, not top down. Some people think using gravity to get the filler flowing downward is the way to do it. Not so, this is how you get air trapped in your joint.
Great bike.

 

[waynebergman]

Nice going etard. Looks good.

 

[etard]

Always braze from the bottom of the joint, up, not top down. Some people think using gravity to get the filler flowing downward is the way to do it. Not so, this is how you get air trapped in your joint.

I actually learned that on the dropouts Gordo, coulda used that advice a day earlier. :lol: Actually, to pile up the brass solder in the gaps, I just flipped the frame around to keep the solder on top. I don't think I have any cold joints though.

 

[etard]

Mocking some things up, everything looks good! Head Angle should be around 71 degrees with a wheelbase of 48".

I dont think I want to use that hub on this bike, just putting it there to get a point of reference.

 

[deVries]

If you put a triangle support strut on each side of your rear rack, then it might support another human?

I really like being able to use the seat stays as part of the rack, didn't think it would turn out as nice as it did. Who needs a pipe bender when you have fire?

Did you bend it freehand w/heating Tell us your technique...

What's the measurement from BB center to rear axle center wheel mount?

Interesting-stylish design & fun work for a first attempt too. 8)

 

[Whiplash]

Nice! O am anxious to see it all painted up and on motion!!

 

[Timma2500]

Nice long wheelbase Etard, should be really stable at speed! Can't wait to see it painted! I like your dropouts too!


Paul