ThermionicScott 

My impression of the UN300 is that Shimano decided they weren't beating the rest of the market with their more complicated (and I'm sure more expensive to make) design anymore, so they decided to join them in putting cartridge bearings on a simpler spindle. It does seem to be well-sealed, so maybe they'll hold up well in the real world...

icemilkcoffee 

I have this generic Chinese Titanium BB on my Nishiki:


It works fine. These Ti BB’s are around 150-160g , vs 300+ g for your typical Shimano UN300 etc. It’s a no-brainer weight saver for me.

FastJake

Please wear a helmet! Breaking a bottom bracket spindle can cause a bad crash and I wouldn't want you to be a "no brainer".

Titanium is not as strong as steel, and Ti bottom brackets have a history of breaking. But maybe you are light enough or easy enough on components that it doesn't matter.

Taxi Rob

IRD has a really nice finish, IDK if they paid Tange extra for the finish work but they're real sharp. Other small volume brands are probably rebadged Tange as well, but no-name Chinese BBs are a crapshoot. I got one with nice anodized cups but it had a lot of extra play, like it already had 20k on it. Sugino still exist I guess, not sure if they make their own or contract them out. I got an SKF to use with a Campy Mirage group, but I can't for the life of me remember which bike it's on right now. It was a lower end model with plastic cups and that Campy style interface and BSC threading, but the tolerances seemed pretty excellent.

wrk101

I've got a drawer full of UN26s from my flipping days. I also save BBs from part outs. An old cup and spindle BB can live again as long as it does not have fatal wear. Added benefit when I find one with French or Swiss threading.

Mulkitez

Whats the difference between the 3922 and the 3912 ?? Other than 6 bucks?

SoSmellyAir

Per the BikeSmiths website, apparently: (1) Finish; and (2) Made in Japan.

Kontact 

Nothing wrong with BBs with nylon cups. They don't seize, corrode or gall. I put one in my Lite speed MTB in 1996 and it is still working.

I recently bought some sub$20 Chin Haur bbs. They mounted easily, produced perfect chainline and spin well. I don't know how complicated a disposable BB needs to be. Seems about as critical as buying name brand butyl tubes.

Hondo6

Pretty sure the BB in @icemilkcoffee 's post above doesn't have a spindle - it appears to be for a GRX/Hollowtech2/other kind of 24mm diameter spindle crankset having the crank spindle permanently attached to the DS crank. This type of BB doesn't do anything except provide press-fit housings for a pair of bearings. Those bearing housings are then screwed into the BB shell.

I'm pretty sure Ti is strong enough for that task. From what I've seen alloy certainly is. (see my later post below)

Regarding a square-taper cartridge BB: I second the Tange recommendation. Tange products are generally of great quality and don't tend to "break the bank".

Duragrouch

Nope, look close, it's definitely a square taper spindle BB cartridge.

Titanium spindle... tough to say; Good steel has higher strength than you can achieve with titanium, but titanium is known for superior fatigue strength. SKF warns against using their stainless steel BB in racing applications, only certified for recreational and city bikes; They say the stainless is more brittle, so no good for hard hammering racers. But they use stainless because for the average joe/jane, a spindle that doesn't rust won't chew up the seals in that way. Same for titanium. It would be good to know if the Ti spindle is rated for racer use.

Hondo6

Yeah, you're right. Brain cramp on my part, hopefully due to a combination of being tired and old eyes.

t2p

have titanium (spindle) bottom brackets in a few bikes

a number of my friends also had / have titanium bottom brackets

road and off road use - some of the riders fairly large / heavy

no issues

early on - many of the bottom brackets were Action Tec - then later World Class (primarily) and Race Face (I believe) when titanium cartridge bottom brackets became available

plan to install a World Class on a bike / frame currently in build stage

still have one bike with an Action Tec BB (pictured above)

many other square taper bikes we have are fitted with UN 71/72 or UN90/91 bottom brackets (which are great)

t2p

would be a challenge to snap that 6-4 titanium spindle