Shimano Dura Ace BL-TT78 brake levers come with set screws, which you can use to adjust your reach to the lever. There are very few levers–road or MTB–on the market that don’t offer reach adjustability. However, the BL-TT78s are the first I’ve encountered that have plastic screws.
To save maybe a gram of weight, Shimano chose to go with plastic screws, and they also cut them extremely short. An extra 3mm would have worked wonders, so what’s the point in making them so short? Not aware of either the material or the length, I began tightening them to shorten the reach of my levers to the point that I could get the first bend of my index finger around them, only to reach bottom, and then snap the head right off one of them. Had the screw been metal, I could have felt that it bottomed out, but because the plastic is so soft, it’s almost impossible to distinguish a difference in torque between the screw turning freely, and the head twisting against the shaft of the screw as it’s breaking off.
Fortunately, I only made the mistake once, so I only had one headless screw shaft to get back out of the lever–not an easy task. The other one, which you can see in the photo above, is still intact, so it was to be my reference for going to the hardware store and finding a new one with the same diameter and thread count. I don’t know how many hours of my life I’ve wasted in hardware stores, trying to find screws, bolts or nuts that don’t exist, and I guess my subconscious decided to save me all the trouble before I did it again.
As I was getting ready to walk out the door, I suddenly got the idea that I should go check some old MTB-style Shimano brake levers, on the off chance that the set screw might have the same thread size. As luck would have it, it did. It was also much longer than I needed, which gave me the ability to cut it down to the right size (middle screw). Hacksaw > file > done. It turned out so well, I went ahead and did a pair, so now as I bottom the screws out inside the levers, they’re at exactly the right reach for my hands.
It was an hour or more wasted because Shimano made a bad design choice, but at least I worked it out. In the end, I gained 1 measly gram.
I’ll leave this posted as a how-to for anyone else who may come across the same problem.