hansel

whats up guys, im a student a Philadelphia university and ive been racing and riding for a while now. Im an industrial design major and am taking a class in the spring that allows me to build whatever i want as a final. im looking to possibly make a steel or ti track frame. (carbon is just out of the question money wise) i know that ti is expensive thats why im leaning towards steel or al. now our design studio has a mig welder with flux (no gas), jigs i can make in studio, and im also trying to get some help from a custom builder in the city. any help to start me off would be awesome, thanks alot!

Colin-

unterhausen

did you look at this thread?

hansel

ahh thanks alot, another question, would you be able to do a carbon tube steel lugged frame, ive never seen of anything like it and i feel it would be alot easier than doing a full steel or full carbon frame, just because carbon lugs are hard to find (at least for me)

NoReg

It would be easier if you could find the lugs, and tubes that actually fit them. Isn't there a thread here somewhere the last few days?

Actually making your own carbon lugs is pretty easy, judging by all those bamboo bikes people are building. There is a reason why the recent resurgence of those is from places that do carbon bikes like Calfee. Read one of the many threads on bamboo, and there are some sites that have people making carbon bikes that way. The great thing about either bamboo or carbon are that they don't need heat, which makes all kinds of stuff easier. None of the cost and skill of the brazing etc... None of the fixturing issues, and none of the distortions to machine out later.

unterhausen

pretty sure there are sets of carbon tubes and lugs. There was a thread recently about mixing steel and carbon. Not that long ago, it was reasonably common to mix carbon and Ti. Of course, that's a whole different ballgame.

Scooper

I'm not into carbon fiber frame construction, but a number of well-known framebuilders use what's called "tube to tube" construction for more flexibility in geometry (no lug angle constraints) and lighter weight. Both Columbus and Dedacciai make carbon fiber tubesets.

This is somewhat oversimplified, but in tube to tube construction the tubes are mitered just as metal tubes would be, and the tubes are assembled in a jig and glued together at the mitered joints. The joints are reinforced by wrapping them in epoxy saturated carbon fiber which is allowed to cure.

If you google "tube to tube carbon bicycle frame construction" (without the quote marks), you'll get lots of hits. I think Nick Crumpton uses this method of construction.

Here's a brief explanation of the difference between tube to tube and monocoque CF construction:

https://www.bhbikes-us.com/technology.php?content=mono

The Crumpton website:

https://www.crumptoncycles.com/index.html

fietsbob

a heat tolerant tube will help make things go better , so think less high tech materials,

I'm still occasionally riding a Columbus Aelle tube set frame I built in the middle 70's.

bulge formed lugs, and joined with brass .. cast BB shell , and fork crown.

hansel

yeah i dont want to make my own lugs, I have a site that i can get carbon tubes in various sizes and shapes so thats not much of a problem. carbon lugs seem to be a b**** to find. i found of some guys in philly that do custom carbon so im gonna try to get into their shop and pick their brain. tube to tube construction seems also very easy, i would probably end up doing a Kevlar and carbon wrap if i did a butted system. but ultimently i would want to do lugs. is there any threads or info about making carbon lugs?

NoReg

Do you have a pic of the kind of result you want? How is a carbon lug different from a wet wrap in a tube to tube, or alternatively how would it be better, since fiber alignment and continuity could be customized at will with the tube to tube.

hansel

i feel like just for me i would me more confident doing lugs, i kinda want it to look like the bmc impec, but with round tubing of course. im still open to doing tube to tube construction but i just need to do some stress tests and get the materials. i also just like to look of lugs


https://competitor.com/2010/07/sports...the-impec_5865

Scooper

The problem with carbon fiber tubes and lugs is not just the limited angles (and remember, carbon fiber lugs can't be tweaked a degree or two like steel lugs), but a limited number of tubing diameters. With all the different CF tubing diameters available and builders' need to use appropriate diameter tubing for different applications, there would have to be a very large range of lugs to satisfy even the the most common angles and diameters.

I think this may be the primary reason the wet wrap technique to reinforce joints in tube to tube construction is predominently used instead of lugs.

hansel

interesting point. im actually leaning towards tube to tube now. im basing the frame off a current track bike that i have now, but i want to do an over sized downtube/bb area and a 1 1/8 steer tube. so pretty much just take my aluminum old school frame and mix in modern technologies. i have a tubing site, so the next thing im gonna need to research is the bb and steer tube, its gotta have a metal insert for threading correct? dose anybody make these for production, or is it gonna need to be custom.

for the bearings to sit in the steer tube it would need to be flanged so how would you go about doing that with carbon? or should i go with an external chris king headset?
i think the reason i wanted to go with lugs is because in a basic view of it it seems like a better system, just connecting two pieces structurally and than gluing it, and not just butting and gluing. but now that i think about it and watch some youtube i can see that it works pretty well. with the carbon tubes, i would need to look into what diameters they supply, i agree that i could me limited with that also with oblonged chainstays. looks like i have some homework

https://www.youtube.com/watch?v=l9x2P...eature=related

Scooper

Damon Rinard answers some of your questions about metal pieces (head tube sleeve, dropouts, BB shell) in a homemade CF frame HERE. Although the Q&A is somewhat dated, there's lots of good info from a technically savvy guy who built his own CF bike.

hansel

awesome, thanks alot for the help, im hoping to go down to a custom frame shop next weekend and try to soak up as much info as i can. between the link page and going down to the shop i should have some good info to get me started. ill have more questions as i continue to think about it and start my drawings etc, ill run them past you guys to try to get some feedback.

thanks again
Colin