wigglrpop

I've got an old road frame that I got for a steal awhile back, and have since converted it for fixed gear use around town. It's a really sweet frame, however I don't have any use for another road frame, and I doubt its worth selling. I'm in the market for a vintage steel track frameset, so I'd rather recycle this frame and try my hand at replacing the rear horizontal dropouts with track droupouts before buying a new frame.

I'm currently working at a steel fabrication shop, and have access to metal working equipment at my university shop as well. I'm hoping for input on different methods of doing this without specialty equipment. My preferred method would be to simply MIG weld the dropouts in instead of brazing (as I'm not familiar with it), however I know the frame is made of thin Columbus SLX tubing. Practically speaking for a downtown beater, should I be worried about (carefully) welding SLX? What kind of risks am I looking at? If I absolutely must braze it, can I do this with a normal torch that my shop might have? How cheap of a brazing rod can I get away with?

Also... would it be completely moronic to try to carefully bend the fork back an inch or so for less rake? It sounds totally stupid but I've always been curious.

I'm sure this sounds brutal, but it seems like a fun project to get some use out of this cool old frame. Thanks for any help with my dumb project! Andy
Andy

clasher

Jeez, you can just sell the slx frame and buy a cheap hi-tensile frame for a couple bucks and mangle that up if you want a fun project. Unless you've hacked all the cable stops and derailleur hangar off someone will likely give ya 50$ for your frame if the original paint isn't too shabby.

wigglrpop

While the point of the project is to experiment a bit, the main goal is to have a good frame in the end. Why would I downgrade from SLX to hi-ten? If I could sell the SLX for $50 and buy a hi-ten frame for $50, what's the point? I like this frame and would rather give it a new use than purchase a p.o.s. frame...

This is a hypothetical project, so I'm more curious about what my options would be should I undertake it.

Live Wire 

Modding old frames is fun, do what you like! That said, the forward-facing horizontal dropouts
On old road frames are 10x better than track drops for a street bike.
To answer your questions:
Yes, a good welder can use a mig on this no problem, BUT, you'll have to do a real good job of cleaning out the old brazing material. Maybe use some drop with extra long tabs that will let you cut away a bit of the stays. Henry James sells some for this purpose.
Yes, you can braze it with any oxy/acetylene torch a typical fab shop would have. Any welding supply store will have the brass and flux good enough to do the job.
Finally, I would never tell someone that bending their fork is a good idea....if your dropout mod failed it would be inconvenient, a fork failure could be a whole lot worse!

wigglrpop

Thanks so much for your response! Literally answered all of my questions haha.

Would you recommend MIG over brazing? After tons of research I'm considering taking on my dream project of building my own frame... so for that I might consider investing in learning to braze, as fillet brazed frames are my favorite. Would I be able to get the job done with one of those bernzomatic MAP brazing handheld torches?

And I planned on picking up some of the old campagnolo dropouts with long tabs on them for this purpose.

Thanks,
Andy

unterhausen

MIG is not generally used on better frames. Brazing or TIG are the most common joining techniques. The Bernzomatic torches with oxygen will cost a lot of money in gas. MAPP by itself is barely adequate for brazing. Heat control will be a real issue for most people.

wigglrpop

I had thought MAPP was the hottest of the Bernzomatic, would the oxygen in fact be? I'm just looking for the cheapest investment since I would only be looking to build a single frame haha. Thanks a ton for the help!

79pmooney

Question - are you planning to ride the velodrome? If not, why track ends? I ask because I have been riding fix gears forever, always on road dropouts and see absolutely no reason to change. Now if you want a longer drop for making cog changes easy without messing with the chain length and you have access to the tools, make a super long road dropout.

I walk my talk. I had the bike of my logo custom made with a horizontal plate dropout made by the builder that allows any cog from 12 to 23 teeth with the same chain. (I think I can stretch that to 24 teeth and now own that cog but it hasn't seen that bike yet.) With the horizontal dropout I can easily do a sub 2 minute wheel flip, lifting the chain off with the spanner end of a Pedros Trixie fix gear wrench and dropping it on to a chain peg. I never have to touch it.

Of course I would have to have track ends if I ever wanted to be cool. (Having been riding fix gears longer than the cool crowd has been alive, I'll settle for just riding what works.)

Ben

79pmooney

Bending forks used to happen all the time. (And every steel fork out there is bent by the builder. Well, OK, a few of the recent ones are straight, set into fork crowns that are raked forward.) In the old days, every bike shop and the tools for bending pipe. Nobody thought twice about adjusting the rake.

That said - why do you want to take an inch of rake out? Do you want a ride so stable that you can ride no-hands while being bumped by a truck? You ADD rake for quicken steering for a sportier ride and SUBTRACT rake for more stable steering. Also, much if the "sweetness" of a frame is in the steering geometry. If you like the ride of the bike, think long and hard about messing with front end.

Ben

wigglrpop

I'd ride on the velodrome if I had the opportunity, but that's very unlikely. I mainly want to be able to put an MKS chain tensioner on there, as I hate adjusting tension on the horizontal dropouts. But yeah its also alot about the fact that I just like the legitimacy of having track forkends on a fixed gear... I really want a real vintage steel frame but can't afford one at the time. I am however surprised by how cheap a set of columbus tubes are. If I can get access to a torch for brazing at my school, I might build my own.

unterhausen

there are chain tugs for forward-facing horizontal dropouts.

MAPP is hotter than propane, but to really get to brazing temperatures, you need oxygen. The cheapest way may actually be to get a used oxygen concentrator, a propane tanks and a real torch and then sell them when you are done. It's not likely to be a money-saving experience if you just build one frame. That first frame is expensive.

wigglrpop

I see a lot of products that are advertised as being able to braze such as this https://orangecounty.craigslist.org/tls/6062597585.html

but I can't tell what is powerful enough. Do I need something stronger for framebuilding purposes? Thanks again for the help.

unterhausen

the brazing torch kit will work, but you'll go broke buying oxygen

wigglrpop

Dang how many bottles would you go through on a singe frame? A bottle per fillet tube joint?

JohnDThompson 

If you're just going to be using it for riding around town, don't bother replacing the dropouts. Rear-facing dropouts offer no advantage, and will make life difficult if you ever want to mount fenders. And any welding would require completely removing any brass from the stay ends. MIG welding thin tubing to thick plate dropouts might be tricky as well, unless you have some experience with that type of joining.

You can pound some of the rke out of the blades if you fixture the fork to support the crown and steer tube and use a rubber mallet to pound the curve out a little. But why bother? The fame was designed to use that rake, and you may just end up with an unpleasant ride.

Really, it sounds like this frame is simply wrong for what your goals are. If you want a nice project that can make use of your access to a metal shop, perhaps consider a frame kit from e.g. CeeWay and build your own from scratch:

Tube and Parts Bundle

wigglrpop

Yeah that's definitely the direction I'm thinking about going. Haven't had a chance to check my schools metal shop to see what kind of torches I have access to, but I'm trying to find the most practical way to build a single frame. Might be that I have to find a local metal shop I can pay to be a member of in order to avoid buying all the equipment.

unterhausen

there are some people that post here that have used the bernzomatic oxygen. Don't know if you can find their experiences by searching, but apparently the bottles run out at inappropriate times, and much more quickly than you would like. If you can find a used oxygen concentrator, you'll be happier in the long run

Nova Cycles has specials on tubing/lugs. They have a decent set for $114 right now with lugs and bb shell.

wigglrpop

Awesome thanks for the info! (Sorry this has basically turned into a newcomer framebuilding discussion...) I was wanting to do it without lugs and fillet braze instead. Is fillet brazing much more difficult? I have a lot of expirience mitering metal tubes as at my job as I build architectural pavilions out of 1" steel pipe.

unterhausen

only you can answer that question. You don't have to use the lugs. I think most people start out thinking that lugs are easier, but really they just hide your mistakes. No hiding mistakes with fillet brazing, or at least not as well. Either way, you should buy some tubing and practice before trying the frame. I think it's fair to say that your first fillet would almost surely be worse than your first lug.