Bicycle Mechanics - Weak Bottom bracket threads - Cartridge or Old school?

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toodman
02-23-07, 08:42 AM
I stupidly crossthreaded a replacement cartridge into my old touring frame. I noticed this only after I had inserted it all the way in and the flange was not flush with the BB. I backed it out and installed it correctly so it now fits, nicely snug and flush, and all *appears* well. But since it also *appears* that most cartridges I've seen seem to place nearly all of their stress on those right-side threads (the left-side plug is often made of plastic) I'm concerned that I may be inviting future stranding on some forgotten road in the middle of BFE should that right-side BB threading fail completely.

So, should I consider an old cup-and-cone spindle since those *appear* to distribute stress more evenly? Loctite? Are there cartridges that distribute stress to both sides? Should I even be concerned?

Sheldon Brown
02-23-07, 09:16 AM
I stupidly crossthreaded a replacement cartridge into my old touring frame. I noticed this only after I had inserted it all the way in and the flange was not flush with the BB. I backed it out and installed it correctly so it now fits, nicely snug and flush, and all *appears* well. But since it also *appears* that most cartridges I've seen seem to place nearly all of their stress on those right-side threads (the left-side plug is often made of plastic) I'm concerned that I may be inviting future stranding on some forgotten road in the middle of BFE should that right-side BB threading fail completely.

So, should I consider an old cup-and-cone spindle since those *appear* to distribute stress more evenly? Loctite? Are there cartridges that distribute stress to both sides? Should I even be concerned?

I believe cartridge BBs actually exert less stress on the threading, so I would definitely advise against moving backward in technology.

Most current Shimano cartridges have the right side threads integral with the cartridge body, which I would expect to be the least stressfull on the threading, since there's no way for the threads to get pushed askew.

Sheldon "If It Ain't Broke (All That Badly)..." Brown