FRAME CLAMPS AND BRAZE-ONS
Braze-ons are brackets that, through the process of brazing or silver soldering, are permanently attached to a frame set. Braze-ons began appearing on bicycle frame sets, in an effort to replace the Old School clamp-on assemblies. Shifters, brake cable guides and even front derailleurs clamps were banned from the scene, displaced by their lighter, cheaper to manufacture, and more user friendly, braze-on offspring. Clamps, that once threatened to crush thin tubes, found themselves gone forever.
When did braze-ons first appear? There was a time, when I thought that the older a bicycle was, the fewer braze-ons it would have. However, that is no longer the case. There seems to be little chronological rhyme or reason, to the appearance of these frame set improvements. My 1958 Carlton was loaded with braze-ons, while its more sophisticated sibling, a 1971 Carlton "Professional", had none. But braze-ons can be a bit of help in dating a bicycle frame set's vintage. Not because of their presence, but because of design and location.
BRAZE-ON: FRONT DERAILLEUR
Most vintage front derailleurs simply clamp into place on the seat tube. This clamping arrangement allows considerable opportunity to improperly locate/position the front derailleur. Additionally, if the derailleur clamp is inadequately tightened, the whole unit can slid down the seat tube, scratching paint, as the derailleur prepares to feed itself into the big sprocket on the crank set.
More modern vintage road bicycles are fitted with a front derailleur braze-on for attaching the front derailleur. These braze-ons permit limited adjustment in the vertical plain, making it still possible to change ring sizes to meet rider preferences. The front derailleur braze-on also allows for minor adjustment when aligning the derailleur with the center line of the chain. Both of these factors allow for easier and more precise installation while reducing opportunity for failure on the road.
BRAZE-ON: REAR DERAILLEUR CABLE STOP
The rear derailleur cable stop is located on the drive side chain stay. In days gone by, this stop was clamped into place. But this clamp on cable guide had an inherent problem. It was clamped to a tapered chain stay, and had a tendency to slide down the taper, throwing shifter cable adjustment off, a little at a time, until reaching all gears was impossible. Today, there is not a single manufactures who uses a clamp-on rear derailleur cable stop. If you run across a bicycle with a clamp-on rear derailleur cable stop, take the time to really start looking. You might run across some other interesting vintage features.
The brazed on rear derailleur stop might be above or below the drive side chain stay. Which is more modern? Can’t say for sure but best guess would be that the stop on the bottom would be oldest.
BRAZE-ON – DERAILLEUR CABLE GUIDE
Shifter cables must make a bend, to go around the bottom bracket, before reaching either the front or rear derailleurs. The oldest means of achieving this was through the use of a simple clamp on bracket. Campagnolo, Suntour, Shimano, Simplex and Hurret, all offered these special clamp on derailleur cable guide brackets.
It took some time before bicycle frame builders began including the derailleur cable guide brackets as an integral part of the frame set. At first, the Braze-On transmission cable guides looked very much like their clamp-on predecessors. This feature, however, was soon to change to be replaced forever with a much better design. The through and/or under the bottom bracket transmission cable guide.
Through the bottom bracket cable guides do not necessarily always run through the bottom bracket, but they will run under it. In fact, most are guided around the bottom bracket rather than through it. Earlier versions allow for the cables to be guided through brazed-on tunnel like eyelets. More modern versions employ screw fastened nylon guides for cable routing. The nylon protects both the frame set and the cables. This under the bottom bracket, nylon protected system is pretty much standard set-up for today’s road bicycle.
BRAZE-ON SHIFTER MOUNTS
The first shifters clamped onto the bicycle’s frame. The most popular position for mounting the shifters was approximately one quarter of the way down the down tube. Cheaper bicycles sometimes had the shifters clamped to the steering stem, a position that proved to be less than user friendly when put into application even though it seemed to make more sense at first.
Shifter clamps, that were mounted to the steering stem, required an additional transmission cable stop bracket. This additional bracket was originally clamped to the down tube where the shifter should have been in the first place. This additional bracket was also used when Barcon shifters were in use.
Barcon shifters are shift levers that were mounted on the ends of the drop bars. The Barcon shifters require that a clamp-on or braze-on bracket be mounted where the down tube shifter would normally be found. These shifters are very nice to use when compared to the popular down tube shifter set, and tremendous when compared to the stem mounted system. I have used both the Campagnolo and the Suntour Barcon shifters. They are just great, in my humble opinion, and I have planned to mount a set on my 1975 CCM Tour du Canada that is presently undergoing full restoration.
BRAZE-ON – BRAKE CABLE GUIDES
The earlier rear brake cable guides were clamp on units, supplied by a number of different brake manufacturers. These clamp-on guides were very fragile. In addition, they were frequently subjected to a rain of body sweat that tended to corrode the tiny screws that held the clamps in place. These clamp on guides were intended for use with fully encased cables.
Generally, in today's road bicycle world, the rear brake cable runs along the top tube of the bicycle, guided by two or three tunnel like braze-ons. In days gone bye, brake cables could be routed on top, or sort of underneath, the top tube. The cable can be a fully cased assembly or a broken case assembly, depending on the bicycle and design.
A full casing rear brake cable is just that, a cable that is completely enclosed in a outer casing with only the ends left bare. A broken casing uses the exact same outer casing, but the casing does not run the full length of the cable. The Sekine SHC-270 pictured offers an example of a partially enclosed rear brake cable and its associated braze-ons.
The broken casing cable will have an outer casing, from the brake lever to a cable stop on the top tube, close to the head tube (five or so inches away). There will be a second cable stop, facing is the opposite direction, near the back of the top tube. The cable casing will resume at the rear cable stop and continue on to the rear brake caliper. The area between the front cable stop and the rear is left cable exposed and this was a very popular system in yesterday's bicycle world. Popular?
Eliminating part of the cable casing, reduces weight. And weight reduction is a popular endeavour when building up a road bicycle. Additionally, eliminating part of the cable casing significantly reduces “cable drag” between the cable and the casing. This reduced drag increases the efficiency of the brake system. The broken casing design fell by the way side, replaced by the fully cased brake cable that is routed along the top of the top tube. The brake cable casing is threaded through three braze-ons which, once again, are pretty fragile. They can be easily crushed and are equally subject to the corrosive effects of body sweat.
Some bicycle manufacturers decided to route the rear brake cable through the top tube of the frame itself. There seems to be no logic or reason to this style of cable routing. At one time I thought that I could use this feature to help date bicycles, but the fact is I cannot. The oldest bicycle I have owned that routed the rear brake cable through the frame was a 1968 Torpado Luxe. The newest, my early nineties Pinarello Trevisio.
I, personally, like the idea of routing the rear brake cable through the top tube. The look is certainly clean and pleasing. But there is a functional issue here, also. By running the cable through the top tube, the cable guide braze-ons are eliminated. These top tube guides present a problem in two areas. First, the are very subject to oxidation. Riders sweat a great deal and this sweat falls onto the top tube. It there is any exposed metal, it will oxidize very quickly. The top tube cable guide braze-ons are frequently found in oxidized condition. The second problem with these brazed on features is that they are very fragile, and a single bump cam crush one or more in an instant. Once crushed, they must be reshaped to allow for cable casing removal and installation. However, as mentioned, these little guys are fragile. Great care must be taken when reshaping or they will rip right off. I know all about this little problem. I have crushed the braze-ons myself and then had one rip off when I attempted to repair it.
I have owned a 1968 Torpado with the brake cable routed through the top tube, just as was the case with my early nineties Pinarello "Trevisio". The point is brake cable routing variations have all been around for quite a while. When trying to use these braze on features to identify vintage, the general rule of thumb would be something like… Enclosed case - older. Broken case – newer. General rule number two. Top mounted brake cable guide braze-ons – newer. Everything else older, with the one exception being routing through the top tube.
BRAZE-ONS(?) – FENDER AND LUGGAGE RACK EYELETS
Both pressed steel and forged drop-outs can, and usually do, have eyelets included. These eyelets are in place to facilitate the attachment of fenders and/or luggage racks. More often than not on forged drops, the eyelets will be threaded to accept a small metric bolt. The presence of drop-out eyelets generally means one thing – not a racing bicycle.
Sometimes, both front and rear drops will have two sets of eyelets included. Such an arrangement will often be accompanied by braze-on luggage rack attachment points on the seat stays and fork blades. Multiple attachment points, such as this, suggest that the bicycle in question is intended for touring purposes.