Saturday, November 22, 2008

Schwinn Sports Tourer Build: Head parts

I didn't start to pull the Schwinn apart or attempt to rebuild it until I understood a bit about how it was going to go back together. And when working with an older bike, this is a process often full of potential surprises, because though there is some consensus around specifications and standards for bicycles, there's also a fair amount of divergence from those standards. These days, that divergence is usually in the name of innovation or performance, but in the old days it appears to have been more based on national or regional industry preferences than anything else. If you spend any time on Sheldon Brown's site, you can't help but bump into this reality, as it weaves its way through many of the articles up there. All things considered, the Schwinn wasn't hard to rebuild, but doing some research ahead of time certainly helped.

An area I did a lot of research about was in the area of the steering head. The Allegro had French threading on the fork's steerer tube and a French-spec inside diameter to the steerer tube, which had caused me some consternation in finding a replacement top nut for the Campagnolo headset, as well as a fair amount of difficulty locating a decent handlebar stem. Truth is I gave up on the frame at least in part because I wasn't finding what I wanted for steering parts.

I wasn't thrilled to learn that the Schwinn didn't use a modern headset spec, but by the time I figured that out I already had the frame. And as I looked around eBay, it didn't appear that there was much of a shortage of old-style US-spec headsets, as it was commonly used not just for Schwinns and the like, but also for BMX bikes. The bigger issue I had was finding a quality headset of this spec, not finding one at all. You can read all about the US/BMX headset spec on Sheldon Brown's website, as usual.

If you follow that link, you'll notice two things, there. First that the headset cup sizes are pretty far removed from other specs, and second that the inner diameter of the steerer tube is pretty different from that of other sizes, which meant I'd have to find an appropriate handlebar stem. I briefly considered replacing the fork and going with a threadless headset to get something a little more contemporary and avoid the challenge of finding an appropriate stem. But ultimately I decided to try to stick with a more original configuration in this case.

The first headset I bought was an Odyssey Dynatron. I found it on eBay, so I didn't have a chance to inspect it at all, and the description was pretty brief. When I got it, I was surprised to find that the grease cups were some sort of rubber or silicone or neoprene or something. The only thing I can figure is that this was an effort to make the headset serviceable in-place -- flip the cups up and out of the way, flush the bearings with degreaser, let them dry, grease them up, and off you go. It's a theory I haven't tested or tried to validate in any way.

I installed the Dynatron, as it seemed to be reasonably well made. The races were clean, the balls looked to be pretty decent and it had a nice level of finish to it. But once I got everything together, the floppy nature of the cups started to concern me. This was a road bike, after all, not a BMX racer. Why would I want soft cups that would allow grease to escape and grime to enter? I didn't want to be constantly checking the grease levels or servicing the headset, honestly, and when I popped the lower cup out of place when installing a front brake one day, I decided to swap it out.

I bought a replacement headset at a LBS. I don't really remember the brand, but it was the only one they had, and when I got it home and looked at it, I quickly wrapped it back up and put it back in its box. This was one of those cheap Chinese units that had rough bearing cages, coarsely machined interior cup surfaces, and appeared to have been made with all the care and finish of a popsicle stick. Back to eBay for another solution.

There I found a new old stock Tange BMX headset. Now, I am certain that Tange made as many cheap headsets in their day as they made nice ones, but the ones I've had have given me no reason to complain. So I snagged it and was reasonably pleased with it when it arrived. The only thing that gave me any concern was the headset's unsealed cups. The gap around the lower cup was fairly wide, and I judged pretty much guaranteed to let crud into the bearings. And unlike the Dynatron, servicing that steel headset would require some effort.

Years ago, though, I recalled seeing a little neoprene scarf from Lizard Skins designed to be strapped around lower headset cups on mountain bikes to effectively create an outer barrier to crud. A little digging online turned one of these up, and that pretty much put to rest any concerns I had about the lower headset seal. The Tange headset and Lizard Skins seal are now providing great service on the Schwinn, and the lower bearing is now further protected by a front fender.

Finding a 21.15mm-steerer handlebar stem was actually pretty simple. Steel units from old Schwinn kids and cruiser models abound, though they're often a little scruffy. I wanted something lighter, but traditional "10-speed" style Schwinn stems seemed pretty rare. So when I found a fairly nice aluminum gooseneck unit that mimicked the lines of the old chromed steel ones, I snapped it up and it slipped right into the steerer like it was made for it. Which it was, of course.

Unfortunately, it wasn't made for road bars. Something I didn't consider (for even a moment) when purchasing the stem was that road bars have a lot more curve to them than city, mountain or traditional cruiser bars found on the types of Schwinns those stems came on. The Nitto 115 bars I had on hand wouldn't thread through the gooseneck stem, unfortunately. The stem's clamp area was too wide and it wouldn't handle the radius on the bars. Back to eBay!

After a few weeks, a suitable OEM Schwinn stem was listed, and I managed to "win" the auction without dropping a lot of money in the process. Once again, it slipped effortlessly into the steerer tube, and this time the bars wound their way through the clamp, too. But older Schwinn stems were apparently not made for sleeved Nitto bars -- the clamp diameter was just a hair too narrow. So I used a pair of wedge-shaped pliers as a wedge (imagine), spreading the clamp just a smidge, then slipped the bars in. As I said previously, they creak anyway, so I'm going to pull them out and use a set of Belleri randonneuring bars. These have a ballooned clamp area, so shouldn't creak, and they have, as an added bonus, a smaller clamp diameter than the Nitto bars.

I guess the only other thing to add re: the head parts is that there's a brake cable hanger for the centerpull brakes setting under the top nut on the headset. It's a chromed steel Mafac part that unfortunately flexes quite a bit under braking. But given that the steerer tube was long ago cut to length for something similar in thickness, I don't think I have enough room to put something thicker and stiffer in there. As I said in my last post, I'm satisfied with the brakes now that I've changed them to Mafac's anyway, but that's another topic.

All for now,


No comments: