Bottom bracket really confusing

boogi11

Hi all, further to my previous post, I'm really struggling with identifying my bottom bracket, I'm confident it is a shimano square taper bottom bracket , and I have ordered the tool to remove it should be he tomorrow.

But firstly jis or ISo? Also their seems to be a lot of different sizes ? How do you measure a bottom bracket.

Finally I can seem to find any good ones? They all seem to be a tenner, are their good ones to be had.


Any help,is welcome

It's on a bianchi neroner 2012 with fsa vero crank

ademort

It,s a JIS fitting and should be 103mm in length.
Ademort

night_porter

Square taper BBs are cheap because they are old tech and very few bikes use this technology nowadays. The main problem with them is the non drive side crank are becomes loose and this rounds off the square and prevents tightening.

If you want to upgrade to a newer type you would need to replace the whole chainset so not cost effective unless you are changing the chainset anyway.

When you remove your BB you will find some writing on the outside of the case and this will tell you what size you need to replace it.

majormantra

Shimano stuff is JIS as are the majority of others, especially cheaper cranks. When changing a BB you need to know:

Thread type (English 1.37x24tpi is most common)
Shell width (68mm on most road bikes)
Axle length (varies a lot)

The cheap Shimano ones are decent enough IMO.

boogi11

Ok , so I'm with you so far..... So I have a campag xenon groupset(apparently not all of it due to the fsa vero compact crank). The bb has failed and needs replacing, without going stupid what would be an upgrade on what I have if I chose to upgrade the chainset, the reaso I don't want to go mad is that if us bike sees me through the summer, it will become my winter bike and I will buy a spare

night_porter

If you are going to use this as a winter bike then just change the BB and stick with the Square Taper, just remember to tighten the crank arms every month.

Alternatively, put a Octalink, Hollowtech 2, BB30, etc type chainset with a new BB/BB cups on. Just go with what you can find cheaply and it doesn't matter who makes it.

Monty Dog

Don't fit any type of external bearing chainset (Hollowtech 2, MegaExo or GXP) if you're worried about durability. BB30 will not fit your frame.

There's no reason why a correctly installed chainset will need the crank-bolts retightening - cartridge-style, square taper bottom brackets were fit and forget - many giving 10-15 years of service without needing attention.

bernithebiker

boogi11 wrote:

Ok , so I'm with you so far..... So I have a campag xenon groupset(apparently not all of it due to the fsa vero compact crank). The bb has failed and needs replacing, without going stupid what would be an upgrade on what I have if I chose to upgrade the chainset, the reaso I don't want to go mad is that if us bike sees me through the summer, it will become my winter bike and I will buy a spare

If you want some bling, fit a Race Face Ti axle square taper BB. About £60 i think. Nice and light, and lasts well. I have one since 1995 on my MTB hybrid.

keef66

In my experience the bog standard Shimano square taper cartridge BBs are pretty much fit and forget. I had one last 10 years on a mountain bike! Don't go thinking that switching to one of the outboard bearing systems like Hollowtech 2 is an upgrade in terms of durability because it isn't.

In your situation I'd just replace the BB with a Shimano square taper.

The size refers to the axle length; hard to measure with the cranks on. Once you get the thing out you'll probably find the size on a sticker on the BB.

You need English / BS thread, not italian

The Mechanic

night_porter wrote:

Square taper BBs are cheap because they are old tech and very few bikes use this technology nowadays. The main problem with them is the non drive side crank are becomes loose and this rounds off the square and prevents tightening.

If you want to upgrade to a newer type you would need to replace the whole chainset so not cost effective unless you are changing the chainset anyway.

When you remove your BB you will find some writing on the outside of the case and this will tell you what size you need to replace it.

I have been using square tape BBs since 1967 and I have never had a crank come lose. Neither do I tighten it every month. That is a sure fire way of buggering up the square taper. Just make sure you tighten it properly in the first place and it will last forever. Get a Shimano UN55 BB the same length as the one you take out.

PS Don't forget that the right hand cup is a left hand thread.

Flexisurfer

I've never had a crank arm work loose on any bike that I have owned?

Campagnolo Veloce bottom brackets are very durable in my opinion and they're not expensive.