My road bike -Dolan L’Etape – has a BB30 bottom bracket with reducer cups for a Shimano 105 crankset. Non-driveside bearing has gone, so looking to replace it.
Is the best option to simply replace like for like and continue using the reducer cups or is there a better Shimano option?
I understand the BB30 design was for the larger diameter SRAM crankset, am I correct?

I changed to the Wheels Manufacturing thingumybob to convert creaky BB30 to Shimano 24mm. This one. No creaking etc since.

If you’re happy with BB30 (someone on the planet must be), just change the bearings. They’re a few quid on eVilbay.

They haven’t been creaky, just not impressed with the longevity of the non-driveside bearing, second time i’ve needed to replace it and i’d rather not have to book it in with the LBS every few months.

This thingamagummy, does it effectively convert the BB to a Hollowtech II system?

The range of bearing types you’ll get inside a HT2 cup are the same as you can get for BB30 only smaller diameter. Its unusual for non drive side to go before driveside.

Changing them is a ten minute job, I would get some decent bearings and dont trouble your LBS, a park tool if your the nervous type a hammer and screw driver if not.

The problem for me with BB30 systems is that the bearings are effectively open to the elements, the only thing shielding the bearings are the reducer cups. Bloody awful design, its bad enough on a road bike – can’t imagine how bad it would be on a mtb!

Without an adaptor, there should be seal over the whole bearing and the bearings themselves are sealed as long as they are not jet washed that would normally be enough.

You may be able to tell I quite like the design, simpler than HT2, more options for bearings and they are quicker to replace once you get the hang of it.
The only down side is the limited range of cranksets without using adaptors. I would still say get some good skf or similar bearings.

The bearings put in by the LBS have a simple press-fit cover over the bearings, not what I would call a seal in any real world application.
What bearings are truly sealed – i.e. completely weatherproof?

..and they should be “sealed” bearings with their own cover but no their not 100% waterproof hence the guidence not to jet wash and why people have winter bikes with un54 type bearings that are more resilient.

I hate getting my summer bike wet, it happens with an unexpected downpour etc but you will be changing any lightweight (inc ht2) bearing frequently if you regularly use them in all weathers.

Because BB30 bearings sit directly in the BB shell, any water ingress (down seattube) means bearings are sitting in manky water – even the best-sealed bearings don’t last very long under water. You can only ride bike in the dry, use mudguards or hang bike up and remove seatpost after every wet ride. Better solution is proprietary adapter like Praxis or KCNC

The only bike fitted with BB30 bearings is my ‘good’ road bike, which mainly comes out on dry days but even so occasionally gets wet.
Ive ordered some new bearings from ebay so will try those, I have a homemade headset press that should do the job of installing them if I do it one at a time.
Still not sold on the idea of pressfit bearings, especially when they are so exposed to water.