Can somebody help resolve the chainline problem I'm now having on a Panasonic frankenbike?

I've just transplanted an Italian crankset and bottom bracket spindle onto my Panasonic commuting bike while keeping the current english-threaded cups.

I've been able to install and center this using a 1.8mm bottom bracket spacer behind the fixed cup. What I didn't consider was another mod on the panasonic that I'd done by stretching out the frame spacing to 135mm to accommodate a rear wheel with that O.L.D having a 7-speed cassette.

Now, when the chain is on each of the two outermost cogs of the cassette, it will rub against the next cog in as it goes to the crankset.

My measurement for the current chainline is 42mm.

(I'm doing this only because I got a new crankset and bottom bracket cartridge for my vintage Bottechia and I wanted to reuse the old crankset. The Panasonic's old crankset was cottered and heavier. In retrospect, I should have known that I would run into this kind problem by using a crankset intended for a rear wheel having 126mm O.L.D. with a wheel having one of 135mm.)

Anyway, what to do now? Put the old crankset back in? Leave it alone? Get a longer ISO-square-tapered bottom bracket spindle?

Oh. And did I mention that the bottem bracket housing on the frame is 70mm wide? But english threaded?

It's only because of this that I didn't believe that I can't use a cartridge bottom bracket. Or can I?

The 1.8mm bottom bracket spacer is needed because the english-threaded cups on the panasonic have thicker walls than those used with the crankset on the Bottechia.

While Sheldon Brown put up a lot of info for Shimano components, there isn't anywhere near as much that I know of for Campagnolo or compatible components.

The only hint that I can google is from this webpage, https://www.velomine.com/index.php?main_page=product_info&cPath=86_83&products_id=722

It's only because of this that I believe the part that I can best use to resolve this chainline problem is a Campagnolo 70-ssx3 road triple bottom bracket spindle or something comparable. I think.

(The part is sold out at this website.)

I didn't think to measure the italian spindle that is now inside the Panasonic. It's not a Campagnolo but I believe that it's comparable to the 70-ss.

Removing that installed 1.8mm spacer that should compensate for the greater asymmetry that the 70-ssx3 will introduce. I think.

Well, what do you think folks?

Take a long piece of sewing thread and tape one end to the inside of the big chainring, at the front of the CR. Now pull the thread back towards the FW/CASS. Keeping the thread taught, carefully sight down the thread and move it until it just makes contact with the back part of the CR. The thread should be just to the right of the center cog on a FW/CASS with an odd number of cogs, or just to the left of a cog on an even numbered one. Change the BB spindle legnth or add spacers to the cup to correct the chainline.

Rather than trying to sight down a thread, find a straight edge or ruler longer than 15 inches or so. Lay it on the outer face of the outer chainring edgewise (not flat because it can flex in that direction) and carry that line back to the cassette. You'll need to compensate for the distance from the centerline between the rings (midpoint of the gap on doubles, or middle ring on triples) to the outer face where your edge is, but the correction should have you end up with the centerline dead center of the cassette.

In any case, spreading the frame shouldn't have been that big an issue if you did it evenly, since the cassette centerline moves out half the distance that you spread.

I think you didn't get the rear triangle aligned correctly when you spread the dropouts. The right stay moves much more easily due to the crimping for chainrings. If it started at 120mm and you spread it to 135mm with paying attention to alignment is almost certain to be mis-algned. That and/or a 42mm chainline for 135mm OLD is your issue. The outer rings CL should be ~50mm.

- Take a perfectly dished wheel, install it in the frame and look closely, if it's off by more than ~5mm you'll be able to see it by sighting down the head tube, seat tube and rim.

Have a question, what chain do you have in there? a road chain or a single speed one? Just rulling stuff out ok?

Do you have a picture of the crankset you are using? and how close is from the chainstay? Looks like it is too far.

Outermost u meant the last large cogs right? Are you using a single chainwheel or double? If single, doesnt surprise me that u have that problem, chain crossing problem more than chain line to me.

Sorry that I didn't get back sooner.

To answer some of your questions in no particular order:

The crankset that I put in is a Mundial 52/42 double with the midpoint-point being the 42mm front chainline that I've already stated.

I took a string, as advised here, ran it along the inside of the outermost (right-side) chainring and found that it pretty much lined up (+/-1mm) with the top of the 4th cog which is the middle one of this 13-15-17-19-21-23-25 7-speed Shimano Hyperglide cassette.

Getting my hands on a copy of "Zinn & the Art Of Road Bike Maintenance" and a caliper, I made some more measurements. With a gap between the cassette and the right dropout (6.5mm) and, using the specs for the cassette and the 135mm OLD, I calculate that the rear chainline is 45mm.

BUT...

Taking a second look at the rear triangle alignment, I estimate that these are off-center by 4mm towards the left (non-drive side). This current situation would be even WORSE if the triangles were properly alligned.

The width of the chain is 7.8mm.

There must be something else out of whack or my measurements and estimates are off. The triangle misallignment should actually COMPENSATE for the difference between the front and rear chainlines. Everything, except for the triangles, should line up.

I took the bike out for my first ride this year and am finding that it's handling quite fine although, with the stop-and-go cycling of my normal commute, I only had the bike in top gear (that is: large chainring to smallest cassette cog) for literally only a few minutes.

The only reason that I'm believing that something's awry is the distinctive sound that I recognize whenever I BACKPEDAL in this top gear. It's a sound that I'm familiar with from a lifetime of using friction shifting: one of an adjacent cog starting to catch the chain as you slowly shift gears but not yet grab it enough to actually shift.

The current triangle allignment has been the best that I could do because when I tried to fine tune this I would always overshoot the amount of bending that I wanted to accomplish. I'm now thinking that the way to do this is to get a bare rear-wheel axle, put on some nuts set to the proper O.L.D., and anchor the triangles together for greater resistance when I try bending these with a wood 2x4 as per Sheldon Brown's instructions on his website.

My estimate for the proper bottom bracket spindle length will be just over 120mm. Where can I get one that is ISO-square-tapered that is under $40? The Campagnolo 70-SSx3 (124mm) should work but I don't know where to find that. What else is there that is comparable? What I'm finding online is either J.I.S. or unspecified.

A complete cartridge bottom bracket may have to be for a 73mm housing. My bike has an english-threaded housing despite being 70mm wide making it incompatible with the Italian-threaded ones.

Many thanks.

(I'll probably end up leaving the bike alone for this year and do all of this when I once again overhaul my bike at the end of next winter. Swapping the cranksets was something I first contemplated over a year ago. I waited until I found a good deal for a crankset on Craig's List.)

You are making this too much complicated of what it is. It does happen when u are using the 42T chainring? If it happens only in the 52T you have a crossing chain problem, if thats the case no matter what u do, it will get noisy all the time.