Originally Posted by
John E
Have any of you TA or Sugino crankset owners experienced any problems with the small inner bolt circle which attaches the spider to the crank? These bolts are subject to very high levels of shear, and I read somewhere that they are failure-prone, but I have no firsthand experience with this.
John, one of my earliest bikes was a Track bike set up with a single TA chainring on a Stronglight 49-D crank arm (the predecessor to the TA). My buddy was the original owner of the bike, purchased new around 1965, and then retired to his basement when he had stopped racing. One reason he had not built the bike back up after stripping the frame for a re-paint was he had mangled the chainring bolt holes on the crank arm. When I bought the bike from him around 1970 I replaced the drive side crank arm.
BUT... the main reason the crank was damaged was that the chainring nuts and bolts had loosened and a couple had eventually fallen out and were lost. Not having correct replacements handy (and I suspect that being young and careless) he had attempted to use 5 simple machine screws and hex-nuts as replacements. These were ill fitting and left a lot of slack in the holes of the arm which then soon "ovalized'. After I had replaced the arm I used the bike with the same set-up for thousands of miles, on the road, and without brakes, which uses more torque than a touring set-up with a derailleur. I never had any problem with damage to the crank. I now have TA or Stronglight versions of this crank arm style in use on 9 different bikes. I love them. I'd feel comfortable bicycle touring around the world using them.
The TA chainring bolt kits do come with "wave washers" which are rather uncommon in the US. These are very thin... well... "wavey" (rather than split) lock washers. So, you really do want to be sure to use these to prevent the cheap looking zinc plated nuts and bolts from loosening. The nuts are a bit longer than the thickness of the crank base and these fit a short distance into the chainring making a snug fit. A simple yet effective joint.
This is one of the oldest bolt circle patterns in all of cycling and Stronglight and later TA had simply adopted this early standard on their alloy cranks. This pattern had been used for many dacades previously on steel cranks from many different manufacturers and there were never issues with sheared off bolts even under the most demanding conditions. Jacques Anquetil had even used a 49D alloy crankset with this bolt pattern as late as 1957... when winning his first Tour de France.
On the Stronglight 49D the "nut" enters the crankarm from the front of the chainring. The TA cranks have a smooth bore all the way through and their nuts enter from behind to rest part way through the chainring bolt holes. ... I see no advantage to one over the other.