Collecting parts to build a fixed gear and dad decided to help out by buying the bottom bracket. Told him the specs and he got this.
Dimensions are right and it would fit but I’m not sure about the plastic thread on the right side. Would that be a point of weakness or am I over thinking?
Granted I’m a newbie to bike stuff.
by JP_Agz
15 Comments
It’s just an inexpensive Shimano BB. The plastic cups can sometimes get stuck in the frame and break/strip when trying to remove them, which is a huge pita. Otherwise they are usually reliable and durable.
totally fine. shimano has been doing that since the mid 90s on their cheaper BBs. the plastic “adapter” only holds the cartridge in position.
Nothing wrong with the plastic thread. It’s just there to stabilize the cartridge. It doesn’t do any heavy lifting. Just don’t over tighten it. I’ve seen those last thousands of miles with no issues.
It’s fine. It’s a lower end but perfectly serviceable BB. That being said, Velo Orange has some very reasonably priced square taper bottom brackets that I have found to be very good.
That bb is indestructible. The more you remove and reinstall it the more likely you are to damage the plastic sleeve, but if you install it and leave it, it will outlast all of us.
I had one of those that outlasted three bikes. Winter bikes, single speeds for winter use in New England. Probably ten thousand of the worst miles you can imagine, high torque loads, rain, grit, and salt. The third bike went in the dumpster due to terminal rust, but with the BB still turning smoothly.
Yeah, the plastic will become a problem when, 15 years from now, you’re trying to get it out again.
Other than that, it’s an ok bottom end Shimano BB – chances are you’ll just screw it in and, indeed, forget about it for the next decade or so.
I had that goddamn plastic bit on one of my bikes. THE MOST ANNOYING thing to take off. Stripped so quickly. And once it was stripped, man, it took effort to get it off. Never again.
Bulletproof
Nothing wrong with plastic in that location since it’s a very big thread. Back in the day, XT and Ultegra level bottom brackets used plastic cups, so it’s not really even a cost-cutting measure.
Low end but fine make sure to put a dab of silicone paste on the plastic threads makes it not stick so much .
It’s the GOAT bottom bracket tbh
I thought it was to limit either galvanic corrosion or rust. A polymer sleeve will be easier to remove and to install, providing a bit of “give” and to accommodate for subtle frame misalignments. Not every bike is manufactured to the highest tolerances.
Damned if you overtighten. Damned if you don’t.
I think this is a solid design decision on Shimano’s part. Most bottom brackets on most bikes are a set-and-forget part, possibly moreso than anything other than the headset, and they’re installed in a wet and dirty part of the bike. Plastic won’t corrode into place if you leave it there for 10 years, and is more forgiving than metal if you do need to remove it destructively.
I’m really liking the Tange/IRD one I got for like $30. Made in Japan… Out of metal