Hi, I’m tinkering with building a gravel bike out of an old Miyata 610 with a 90s era 105 group. The bottom bracket doesn’t fit the frame but the 105 cranks are square taper, as is the original BB.

Should I buy a modem BB or just repack the original unsealed BB?

Cups are too big.

ummmm....

I'm new at this. 😁

Is threaded. Too big in circumference for sure. Didn’t measure width.

Hey, I didn’t name them cups... Who’s in charge of bike part nomenclature?

original fits but is an old style (not sealed bearing). I was going to install the newer one (along with the rest of the 105 group it came from) and realized the newer one didn’t fit.

Question is: is a sealed BB much preferred to an unsealed older version? I’ll be riding mostly gravel roads.

Although it seems highly unlikely, it sounds like the 105 group has an Italian bottom bracket as Hillrider pointed out. Italian bottom brackets are extremely rare. You just need a new ISO bottom bracket (1.375″ diameter x 24 threads per inch or TPI). Measure the length of the spindle on the old 105 bottom bracket to get the proper length.

K, good info. Will update to cartridge.

Further question, should the spindle length match the 105 length or the length of the original spindle (non cartridge)? I’m not sure that they’re different but wanted to be clear.

Also, what are the key measurements on a BB? Spindle length, threads per inch, diameter? Anything else? Then there’s making sure it works with the crank - square taper in this case.

Any my other considerations? Feel free to point me to Sheldon B if I’m asking basic questions. I have not done my homework yet.

The bike that the 105 group came from is a Canadian made Aquila Strada Max from the 90s. Toronto built, aluminum frame.

Yep. I had to replace the bearings on a Phil once.

I should also also point out that I have had terrible luck trying to get a sealed bearing B.B. to work with my cottered cranks. Dammit.

We have buckets full of cartridge bearing bottom brackets at my co-op and exceeding few of them have failed. We get a few but very few considering how many we get in. On the other hand, they are cheap and easy to replace.

From my own personal experience, I’ve been through dozens of bottom brackets on dozens of bikes. No one of them has actually failed. They’ve been upgraded but I’ve never had one of any flavor from square taper to external that have failed.

On the other hand, I’ve had lots and lots and lots of loose bearing bottom brackets fail. Most of the “failures” have been due to the spindle pitting but I’ve pitted a few cups as well. The seals became better over the years but they didn’t get good enough to stop the pitting entirely.

If the bike has a loose bearing bottom bracket, I would tell people to avoid using a pressure washer near the bearings. But a pressure washer isn’t a problem with sealed units. If your customer would have used a pressure washer liberally, they would never have corroded the bottom bracket to the level in your picture. The problem is salt and it needs to be removed as quickly as possible. Of course that level of corrosion doesn’t happen overnight nor even over a single season. It took many years to do that kind of damage.