Changing a crankset

[Gunk]

I suspect you've got water getting into the frame - mine looks nothing like that after 2 years !

We get loads in at work looking like that, usually bikes that have been left outside, as @Punkawallah has suggested, I make sure the replacement BB is smothered in grease when I fit It.

 

[presta]

The unbranded square taper BB that came with my bike lasted 16,300 miles, and the Octalink that replaced it did 28,300 miles not out.

I make sure the replacement BB is smothered in grease when I fit It.

I plastered the cartridge and frame with as much grease as I could pack in, but it didn't stop the threads rusting. The mix of grease and rust that came out looked a bit like breadcrumbs and olive oil.

 

[si_c]

BB-UN55 would have been my recommendation - SJS still have a few in stock @ 115mm width if that's of use. The Spa Crankset is pretty great, you'd struggle to find a triple in a low range like that anywhere else particularly with a HT2 type BB.

I've found HT2 BBs to be pretty reliable even when run through pretty terrible conditions if you keep on top of maintenance but a properly sealed cartridge BB is always going to be better just because of it's nature. That being said there are a lot of truly awful cartridge BBs, one I got from an LBS disintegrated as riding.

If you can get one, look for Tange or IRD, they're better than the old BB-UN55 - well built and reliable although they are bit more expensive.

 

[DCLane]

If you want a nice square taper bottom bracket go for a Velo Orange one. Lovely but pricey.

There's one in son no. 2's orange Carlton Corsa, which has been stored outside under cover for several years, and it'll probably outlive me.

 

[Yellow Saddle]

1 Experience - managing an LBS
2 Bearings are further apart and thus better support the axle
3 Bearings are better quality (and can be upgraded to even better) [. . . and yes you can swap bearings in most external cup BBs with the right tools)
4 Experience - with my own fairly high-mileage bikes

Jeez brother, what planet do you live on? NOTHING will give you longer life than a high-end Shimano square taper bottom bracket.

 

[Yellow Saddle]

This is the UN300 that I replaced a few weeks back, from my folder after 6 months winter commuting and general knock about riding. My commute is only 6km, so in total this BB has probably done 600km. The last one didn't last too long either, in my experience the UN300 is utter rubbish, nothing like as well built as the old UN55.

The External BB's on my Gravel and Mountain bikes are used all year round in filthy conditions and last an absolute age.

Just my experience.

View attachment 765979

Nothing I see there has anything to do with Shimano. That BB was fitted into a BB shell with no drainage hole. Futher, it was ridden on salted roads with no rinse-off every day. Gauranteed.

 

[chriswoody]

Nothing I see there has anything to do with Shimano. That BB was fitted into a BB shell with no drainage hole. Futher, it was ridden on salted roads with no rinse-off every day. Gauranteed.

Mmm good point about the drainage hole, I'm actually not sure if there is one, I'll tip the bike up later for a look.

It's from my folding bike, so the shell is actually separate from the seat post, it's welded in front of it, so the water has come from the side, not from down the seatpost. I'm definitely guilty of not rinsing it off everyday, but the roads and paths I ride here in Germany are generally not salted.

What I find interesting is that I've ridden this bike in exactly the same way for the last ten years on the same daily commute and utility rides. Yes I don't wash it as often as I should, but the bike is kept under cover at work and inside at home. The UN55's lasted for years under this abuse, yet the newer UN300 ridden under the exact same conditions only last 6 months. I'm sorry but the only conclusion that I draw from this is that the it has everything to do with the poorer quality of the newer UN300.