June 2004

Ok, so everybody is coverting bikes to singlespeeds these days, but the usual prerequisite is having a frame with suitable dropouts. Well, here at URBC we go the extra mile. If the dropouts aren't cool enough, we make them cool enough! This is a single speed FRAME conversion folks. Delicate Japanese tubing will be heated to within an inch of it's life! Frame bits will be savagely ripped off! Shifter cablestops will be heartlessly eradicated!

The donor bike is a 1993 Sumpjumper. My first bike, and still a really great little ride. Tange tubing. Tig welded, but all the stops and dropouts and stuff are brazed on. Actually the rear brake bosses are welded, which is interesting. The stays are quite beefy, so the added heat stress of welding would have been well tolerated, and so welding them is probably stronger in the end.

Of course the first step is to strip the paint off the frame. Then we can immediately go to work with the torch! I am using an Oxy-Acetylene rig with a very small tip. For even less heat you can dial the gas down more than usual and adjust the oxygen to match. Some texts recommend a slightly carburizing flame to reduce the heat further. I chose to stay with a neutral flame.

The dropouts are a bit difficult to remove because you must heat both sockets simultaneously. Heat the dropout first, then the frame. Be patient, and eventually it will just pop out.

While I was at it, I removed the bridge that held the cantilever cable stop. Remember, this frame is pre-V-Brake :) I also removed the rack eyelets, and the shifter cablestops on the downtube and chainstay. I like the way frames look when they are nice and clean.

I wanted to use Breeze-in/Sub 11/Surly dropouts, but the stays were designed for flat style dropouts, and there was not enough stay to rework for Surlys, so I chose these Paragon-made dropouts from UBI. They are CNC machined, so the nut face is raised, which is nice. And of course who can turn down a built-in bottle opener :)

A quick note on terminology... Technically ther are not dropouts, but rather "fork ends" because they are not oriented vertically to allow the wheel to drop out of the drop out :) But dropout is the commonly accepted term, and conveys our intended meaning just fine, so that is what I will use :)

I used plain old brass brazing rod and common "Stay-Silv" flux, which may have been designed for silver brazing, but seems to work just fine. I am curious what bike-specific meterial would be like to work with. Here are the droputs after brazing, before cleaning up. I used an old sxle and quick release to hold the dropouts parallel and spaced correctly while brazing. I brazed one in, then put a wheel in the frame to make sure the second dropout would be lined up well enough for the wheel to be centered. I am fairly certain I overheated the living shit out of the stays, but they are nice and beefy, so they didn't seem to mind.

Because of the size and shape of the new dropouts compared to the old ones, both the seatstays and chainstays were effectively shortened by about a half a centimeter or so. I was a little worried about the brakes still hitting the rim, but there is enough adjustability in most brakes, so it will be no problem. Good thing, since it would not be easy to move the beake bosses.

Here you see the state-of-the-art URBC paint facility. For paint, I decided on a nice brown, which I layed over a coat of zinc-rich primer for extra rustproofing, especially around the dropouts and spots where chips tend to occur - not that chain slap will be an issue :) That zinc rich primer is really heavy, so weight conscious folks might skip it completely :) The handlebars I had been using on the bike were red, so I thought I had better paint them too. They are aluminum, and I have heard that it can be difficult to get paint to work well on aluminum, so I didn't strip them and just painted over the existing paint. It probably won't hold up very well, but we'll see.

Man those dropouts look sweet!

Hmmm... From this point of view it becomes rather clear that the dropouts are not very well aligned with each other. Next time I do this, I will have to build some kind of jig to hold everything in place and insure straightness.

Maybe I have watched a little too much Monster Garage, but I just had to put some flames on it. First I drew out the flames, then traced them onto 2" blue masking tape laid out on a nce glossy magazine cover so they will peel off. Then just apply, paint, and remove before the paint seeps under the tape. I waited a little too long and got a bit of seepage - oh well.

Do not adjust your set. Those are indeed Hello-Kitty-pink flames on a brown frame. I think it looks cool, and everybody knows that pink bikes are incredibly macho!

The final product. As soon as I get my parts from Momovelo, including bomber Soma Fab New Express tires, funktacular Stronglight Delta headset, and confusingly gender neutral Kronan bell, this dirty girl will hit the streets!

Here it is all built up. Those 1.75 inch wide tires are a lot skinnier than I htought they would be. I broke the stem clamp bolt like a jackass, but luckily I was able to replace it with a bolt ouf of a brake lever. The Stronglight headset has a pretty high stack height and so the top nut only has a couple threads worth of purchase, but it should hold.

My big plan was to build a bike for riding to work, but here I am at work, and I drove here. 7:00 in the morning is just too frickin early to ride a bike.

This was a really fuin project, and I am suprized how well it turned out. I'm not sure what the next phase wil be. I would love to build a lugged frame, but I think I might do more dropout replacements first. I have a sweet lugged frame that I would like to put track dropouts on, and maybe try to shorten the chainstays a hair. Whatever I do, it will involve some sort of alignment jig. I really screwed up the lineup of these dropouts - lining them up with a wheel just didn't cut it.