Miche Primato BB on shimano cranks?

Hi,

I am currently running shimano 600 cranks with a 110mm BB.

My chainline needs very slight tweaking and I would also like to move my chainring to the outside of the spider where it should be.

Then using a smaller BB to bring the chainline inward. But I have the problem that my spider is only 2-3mm away from my chainstay. So everything is getting close, and the measurements fiddly.

So I was thinking of getting a miche primato BB despite the many negative reviews, as they are adjustable, yes? - So I can tweak it to the exact psoition I need.

Just want to double check they are compatible with non-primato cranks and if Ive missed an easier solutions.

Thanks.

miche primato is iso and shimano jis?!? so may have some indfifference.

my miche primato bb is a piece of shit dont get one. its a tight fit with my old frame and hard to adjust so everytime i complete a crank it hits part of the frame. the result you know when im comin up behind you by a loud click every second

my miche primato bb is a piece of shit dont get one. its a tight fit with my old frame and hard to adjust so everytime i complete a crank it hits part of the frame. the result you know when im comin up behind you by a loud click every second

doesnt that just mean that either the BB is too small for your frame/crank combo OR you just need to adjust it?

There is a thread somewhere on JIS and ISO. ISO cranks sit a couple of mill further out on JIS spindle, or the other way round. But I can't remember which way round it is, so you will have to look for the thread.

Miche BBs are hit and miss, I have had 6, 4 have been great, as smooth and free as my campy record, 2 feel like they are running in gravel filled treacle.

wouldn't be a good idea with the differing tapers. why not get a 107 bb, and file off the tabs on the inside of your crank, that should give you the space. and miche bb's are terrible.

Get a ballpunch and hammer and ding the tube slightly, if its ok for master frame builders it will probably be ok for you.

It makes me wince when people talk of hammering, punching and pressing great dents in chainstays. There is a good chance that you may ovalise the tube and crack the brazed joint between chainstay and BB shell, even if you're really careful and use the right tools. I'd guess that frames having pressed tubes are usually shaped and stress relieved before assembly so manufactuers don't have that risk.

Are you going to use the cranks as doubles ever again?

If not, file off the inside tabs. You could even file them down so you have about 1.5mm left on them, probably removing 2.5 mm in the process and still be able to use the inside if you move the cranks to a different bike. If you've already got 3mm of air between the tabs and chainstay, that gives you at least 4mm of movement. The maximum shift of the spider you could get is 3.5mm by using a 103mm BB.

Assuming the dimension between centre line of the chainring on the inside and on the outside is 7mm ((half thickness of chainring x 2) + width of spider across faces):

With a 103mm BB, putting chainring on the outside may give you a movement of your chainline from its current position by 3.5 mm to the outside. Is that what you're after? Any less than 3.5mm and you'll have to keep the chainring on the inside.

From your picture it looks like the cranks could take moving in by 3.5mm, but make sure by measuring that there's enough clearance between cranks and BB shell/cups.

Good luck.

both

both what?

sry: didn't realise who you were replying to :)

Ive just fitted miche cranks with miche bb. I put the bb in symmetrical initially, but the inside of the chainring bolts scraped my chainstays, so Ive shifted the bb over a tad, theres about 2mm of clearance if that, but it works fine.

Try Campag Chorus - 102 mm and cheaper than Record. Didn't last very long but will way outlast miche.. Narrowest I could find at the time.

ChrisNW: thanks for your very detailed reply.

I started to consider the hammer and punch aswell! Filing every chainring tab would take forever and be really messy I fear.

Does anyone know where I can find out for certain whether they be any taper issues? If one is indeed JIS and the other ISO?

I always thought that modern shimano crnaks & BB's are ISO ?

I started to consider the hammer and punch aswell! Filing every chainring tab would take forever and be really messy I fear.

It all depends. If you've got a decent rough cut file it will take no time at all, you're only filing aluminium which is really soft.

I think nothing of cutting/filing stuff to size, but it depends how confident you are of not cocking it up. Don't rush in until you know its all gonna work out.