A customer had us build a bike for him for the Mount Washington Hill Climb back in 2003. He used it in the race every year until last year, when he asked us to convert it to a flat-bar road bike.
The frame was a Trek 5900 SL. The carbon fiber road frame uses a bracket for the front derailleur rather than a derailleur with its own clamp. This was irrelevant on the original build, because we did not mount a front derailleur. In fact, the frame had no derailleur bracket when he had the bike delivered for its road conversion. Finding a bracket to fit a frame that was nine years old -- prehistoric in current bike industry terms -- was a treasure hunt. It was easily resolved once we found someone who knew the right part number at Trek. So we were all set, right?
Come on. This is the bike industry we're talking about. The business that's been killing the wounded and eating the dead since the 1990s. The group that puts its elderly out on the ice floe to die before they're even out of grade school.
Our customer wanted grip shifters. He also believed that the road conversion would be a simple matter of adding the parts the climbing bike had done without. It's a reasonable assumption if you don't work with this machinery all the time. Even I felt that the front shifting would be the least of our worries once we rounded up a very basic array of parts. A ratcheted front Gripshift is a simple device for pulling cable. A front derailleur is a simple device for pushing a bike chain toward a chainring with which you want it to engage.
Trigger shifters and road brifters only pull a specific amount of cable. A compatibility issue there is no surprise. It's expected. The customer's request for the closest thing to a friction shifter seemed to get us around that. But the shifters we use technically come from the "mountain" category and the only front derailleur that would work with this frame mount and gear range comes from the "road" category.
The shift to the middle ring on the triple crank went well enough, but that last little twist to make the big ring was incredibly stiff. And no matter how much cable tension I put in the system, the arm on the Sora FD-3503 is too short, and angled in such a way, that it barely swings far enough to clear the ring. The shifter never manages to pull it all the way to its limit screw.
With no alternative parts, I had to make these work. Introducing the Cafiend Leverage Enhancer.
The arm of the derailleur is extended with part of an old brake cable adjuster. It's bolted to the arm, where it braces against the cable routing flange to keep it from rotating downward when the cable gets tighter.
At the shifter end, the diameter of the grip seemed a little small too. We've had older riders complain that they have trouble with that. Lacking anything more elegant, I built it up with several layers of inner tube. If he likes that but wants something a little zootier I'll get some of that black foam insulation they use on air conditioning lines, and snug it on there with some super-fat shrink tubing. He won't be back until next summer, so we'll have to wait and see.
The system works. Shifting is easier. I have one more brake adjuster that's a little longer if he wants that, but we start to get a little close to the rear tire then. If the rider wanted to put on something cushier than a 700X23 things could be tight.