juvela

not too long ago member crank_addict began a thread on cotterless steel chainsets:

https://www.bikeforums.net/classic-vi...el-cranks.html

in the course of web wander earlier today came upon this blog post stating that the steel-to-steel interface on these sets has a tendency to work loose. this was the first had heard of this phenomenon and wondered if others were familiar with it.

Bicycle Specialties: Aluminum and steel cranks.

most readers have probably not had much opportunity to pedal or service some of the more exotic sets mentioned in the above forum thread such as the gnutti splined or the magistroni zenith and super zenith models.

however, many will have experience of a set such as the nervar sport cotterless which came on the raleigh super course mk ii bicycles and some french machines in the mid-1970's. there was a production batch of these which came through about 1974-75 which had a quality control snag where the brooch in the arm was improperly done and arms would not seat correctly on the spindle. perhaps the q.c. inspector at peyrard had a bit too much vin ordinaire with lunch one day... we may have a forum member who worked at a raleigh shop at this time and might recall receiving a batch of replacements to solve this problem.

have noticed a number of modern inexpensive cycles from asia coming through with cotterless steel chainsets. some readers are sure to have experience of working with these. any difficulties with them working loose?

would be interested to learn of the experiences from other readers on this topic.

thanks for reading.

dddd

I had those Nervar Sport steel arms on my Raleigh, and never had them loosen.

After I replaced them with a complete, BB and crankset that was Sugino Maxy, I did have the arms loosen.

What I've concluded is that it's the bb spindle type that usually comes with cheaper cranksets, the spindles that have integral 10mm threaded stud that gets secured with a nut.
These nutted spindles, as came with my Sugino Maxy replacement crankset back around 1974, do have a tendency to loosen.

Because of the coarser threading on those studs, and made worse by the larger diameter where thread friction is effected, the tension generated by a given amount of tightening torque is considerably lower, and so does not seat the crankarms with as much force as when using the normal, fine-threaded, 8mm bolts.

Even worse, additional tightening tends to break the threads free of those integral studs, as shown below on a spindle that cracked, the threads chipping away on the opposite (top) end from the end that cracked. That's low quality all around.

I note that Shimano never used such a fastening system on even their price-point cranksets, and advise that such bb spindles be re-torqued perhaps more than once after being put into service, in lieu of one-time tightening at a torque level that might be reliably tight.
Note also that the nuts are always toothed with a fish-scale, one-way pattern to help with retention.

John E

The nutted spindle system used on the early Sugino Maxy cranks is indeed prone to failure.