Originally Posted by
zacster
Wait, what? A plastic knurled edge flush with the arm is a hazard? GMAFB. Just look at the pic above of that after-market cap, and I wouldn't even have it protrude that much, nor would I make it 7075 Al, just plastic. And even further, the pinch bolts are what hold it on, the cap is just to adjust the preload. Get rid of it altogether. Make the cap a tool to adjust the preload that comes off and stays off and just include it with the crank. And this brings me back to my first point, why not just include the plastic tool? It is a cheap piece of plastic.
It may be a 20 year old design, but it is a pretty poor one.
It's obvious you don't have much experience with this system. The crank arm won't stay on if the plastic preload adjuster isn't installed. That is precisely why Shimano added the stopper plate/pin to the design, it didn't exist the first couple of years of HTll. The crank axle isn't tapered at all, just splined. You use the adjuster to pull the crank arm on and create the proper preload. You then tighten the crank arm bolts to the specified torque, this tightens the axle around the adjuster so it won't loosen up. The preload adjuster backs up the crank bolts, the crank bolts back up the adjuster. The tool was included with cranks for years, I guess Shimano now thinks there are so many around they don't need to make them anymore. There are also lots of aftermarket tools.