bottom bracket spindle lengths.
 

Let me start off by saying I'm a long time lurker and have finally decide to join.

I have this 1986 Bridgestone 500
A year ago a fell on top of it and severely bent the front wheel.
To me that was enough of an excuse to make some upgrades.
I found a donor bike that I took some tricolor bits off of and sold the rest to break even

With the upgrade I went from a 6 speed freewheel to a 7 speed freehub.
When I'm on the smallest gear the chain rubs on the outer chain ring.
I wanted to get a new bottom bracket
I checked Sheldon Brown's info for lengths
According to the info the 6400 had a 113mm spindle
Can I just buy same size bottom bracket and ride away
Or is there other factors.

I only ask because I read older posts that said the bottom bracket length is determined by the crank used

I have a shimano 600 6207 crank by the way.

Sorry if this is an obvious answer but I've never worked on bottom brackets before

You'll be fine with the 113mm spindle recommended. generally the factors in choosing BB axle length are the crankset and bike type. You already took care of the crankset issue by checking Sheldon's site. the bike type comes into play in terms of how far out the chainstays flare. But you're riding a road bike, which is meant for a crank like the 6400, so you should have no problems.

Thanks for the reply.

Just to be clear
Im using the stock crank (6207) and not the 6400

The info I referenced was for the 6400 crank which I don't have anymore
So I figured id use the same length axle for the 6400 crank*and use it on the 6207 crank

Don't do that. Switch to the big ring before you make it all the way to the smallest cog in the rear. ;)

+1 The large chainring/large cog and small chainring/small cog combinations are both best avoided, as they give the worst chainline.

I've never given that idea much thought.
I do notice when its on the big chain ring and smallest rear cog the chain line is perfect.

I would keep it the way it is
But I'm sure the bottom bracket should be changed
It makes a sort of grinding/vibrating noise when I on the
biggest ring and smallest cog

Take a look at the overall chainline. Since you are running 7 speed in the back, if you take a steel yardstick (or whatever) and put it between the front chainrings, it should hit the 4th sprocket on the back. You can sight this as well. If not, then you need something changed in your bottom bracket. If it does run straight back to the middle (4th) sprocket, your problems lie elsewhere. The bottom bracket should match the proper specs for the crankset you are using.

I'm having trouble figuring out which crank is going to be used here, and/or is in use now.

If the crank is still with it's original bottom bracket spindle, the chainline should be correct.

The older 62xx cranks might have used a 116mm bb spindle, but this would be a small difference from the 113, that's 3mm divided by two.

But the crankset shouldn't cause noise when the bike is in top gear, perhaps the chain is making noise because of a rear derailer issue?

Where exactly is the noise coming from?

He's cross-chaining in the small/small, not in top gear. (I think?)

If it's true that the small cog and big chainring has a perfect chainline, while grinding/vibrating noise at the same time, the only explanation for the chain grinding/vibrating, while the chainline is "perfect" would probably be the chain rubbing up against the front derailleur fence.

As mentioned above, according to velobase.com the BB spindle for your crank (6201) is longer than the 6740 by 3mm; 116mm double/119mm triple; but this would not result in the big ring and small cog lining up; it would be the opposite. So I'm thinking your perception of the perfect chainline might be off; as mentioned before proper chainline should be between the front chainrings,to the 4th rear cog. With the BB spindal being a little short, the chainline would probably aline with the 5th cog (next largest).

Let me clarify

By perfect chainline I meant the big chainring was lined up with the smallest rear cog
The small chain ring is lined up with the 4th cog as is.
Between the rings lines up with the 3rd cog.

The noise I'm pretty sure is caused from a worn bottom bracket.
It's probably been years since its been serviced. When I bought the bike, the first time I changed the tube it had a bridgestone tube .
I never serviced it because the crank arm dust caps are stuck so I put it off till now since I decided to work on it again.

If all is fine why does the chain rub on the outer chain ring?
Could it be that I also changed the chain rings from the 6400 to the 6207 crank?
I also want to bring up that when I had the stock chain from the Bridgestone on there it didn't rub the chain ring.
Even with the switched chain rings.

The crank on there now is the 6207.
Its the crank I will be using.

I didn't even bother to check the length for that one
Thanks for bringing that up

Between the rings line up with the third.
The small chain ring lines up with the fourth

[MENTION=385849]MacGyverBurrito[/MENTION] - I think you have the information you need to make adjustments. Read all the posts more carefully. Your chainline is off.

You appear to have two issues. 1. Chain line. 2. BB lube needed or replacement. figure out what the adjustment to the chain line needs to be and pick a new spindle length and any other parts needed to fix the BB. Read Sheldons description of chain line adjustments.