Hi,

So im currently replacing my bottom bracket and need to buy a new one,

I measured the old one and the lengt of the spindle is 115mm, is it possible to use a 111 mm instead?

The BB shell is 69 mm wide.

You may have chainline and/or inner chainring clearance problems. What make/model is the old one? The new one? Your crank? Chainring sizes? Chainstay length?

All it say on the old is 'CI - MEC ITALY' and im looking for a new campagnolo to fit but hasnt bought one yet. The crank is Ofmega 165mm - Chainrings 52/42 - Chainstay 42cm

If i remember correctly a mechanic that looked at the bike a while back said the chain was hitting the inside of the fork so maybe the 115mm bracket was the wrong size from the beginning

I'm thinking 111mm is going to be too short especially if you plan on keeping your current arms. How much clearance is there between the inner chainring and the chainstay?

Hard to measure since I removed everything from the frame but I quickly assembled the BB set + crank and did a quick check and it looked like 3-4 mm to the outside of the chainstay

Do you mean the chain was hitting the seat stay back by the cassette or that the chainring was hitting the chain stay?
Sounds to me like you should thread the BB back in on the right side only and put the right crank arm back on loosely and take some measurements.

I assembled it quickly and took the measurement. The chain was hitting the seat stay next to the cassette, I can see the mark the chain has made on the paint.

If it hits the inside of the seatstays the most logical thing would be to use a narrower bb?

If I understand the issue, your chain is rubbing on the seatstay by the dropout. If that is the case, changing BB isn't going to fix the issue.

Is there any way to fix this issue? maybe its enough to put in spacers?

Did something get changed on the bike to cause this (was the hub overhauled)? What size is the smallest cog on the cluster/cassette? Sometimes people change from an 11 or 12 to a 13 or 14 and the larger diameter sprocket causes the dropout to interfere with the chain. Otherwise it's time for a spacer on the driveside axle or file the dropout. You might need to redish the wheel when you add the spacer, it can get complicated.