Is 1mm too tight a clearance between the chain stay and the crank arm?

you already know the answer

Looks like there's still paint on the chainstay, so he doesn't know that the answer is yes, and I guess he wouldn't have asked if he already knew that the answer was no 😉

I guess he wouldn't have asked if he already knew that the answer was no

Meh, if he didn't know it was too tight he'd be out riding and not seeking validation on here.

seeking validation

Welcome to my life

Put some helitape on the chainstay, and go sprint up a hill.

I was more asking how to solve it.
In the end I've serviced the old BB, and put the old cranks back on, but now have bling bits lying around, and that is just fucking annoying.
I suspect- without crimping the frame (alu so fuck that) its a no- go.

If your BB looks like this, you could space it away from the BB shell? Silver ring here is a spacer.

The DS has that lip, the NDS rotates in to meet, I'm uncertain if I could find one, plus then I'd have probably the same problem on other side. I think bike will have to become a skidder and I'll build something else for training.

Hmm. Sorry to barge the thread, but I have an even more extreme ‘clearance Clarence’ issue. You maybe can’t make it out in my rubbish picture but I reckon there’s no more than a mm between inner chainring and the stay.
I mean, it clears. But I think I’ll die if I ride it.
Italian threaded, Mirage ISO sq taper BB, 115mm axle, Mavic triple chainset (but only running as a double.)
Would the shim thing mentioned up-thread work? I can’t see how, it won’t lengthen the axle or does it create more offset?

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This is a great answer. Thank you.

Would the shim thing mentioned up-thread work?

Only if you have clearance to play with on the NDS, because you're moving the entire BB assembly to the right. I have done this and it works.

I'm not sure I get what the problem is... if you have a square bottom bracket, just get a new one! They come in all type of lengths! Some other types of bottom brackets also have different lengths but probably not as many as square!

If you have a 114mm, just get a 120mm! Bum! You got 3mm extra clearance...

I’ll check that, cheers!

Yes, appreciate that.
But spending another £50+ on a hard-to-source bb versus seeing if my free shim hack works first seemed like a better plan.
It most likely won’t be but I’m a cheapskating bodger.

just get a new one!

Not everyone has lots of spare time and money sloshing about. A bit of forward planning on compatibility is a good idea, but I'm often just trying to make things work with parts lying around at the shop.

Not sure you are looking at some fancy, specific BB but decent shimano square BB can be found on eBay in many lengths for 10/20£. Another idea, maybe someone could start a thread just to change BBs?Guys adapting road bikes to ss are always looking for short bb.

Just to add... Those spacers someone mention before were designed to adapt a 73 mm BB to a 68mm frame and not to increase/decrease axle length.

https://www.ebay.co.uk/itm/Square-Taper-Bottom-Bracket-Bicycle-Bottom-Bracket-Set-68mm-Mountain-Bike-Axis-/174720156507?_trksid=p2349624.m46890.l49286

Or a bit more reliable Shimano:
https://www.ebay.co.uk/itm/Shimano-ES25-ES300-UN26-Bottom-Bracket-BB-Octalink-Square-Taper-Sealed-Cartridge-/393288615765?_trksid=p2349624.m46890.l49286

Pretty sure you can find even cheaper second hand. Got a really cool carbon BB for 25£ second hand awhile ago

Apologies, my reply came across a bit sarky, didn’t mean to be.
All good suggestions there. I need the ISO Campag as it’s (a bit more) compatible with the Mavic c/s. I nearly bought a Mavic bb then couldn’t find anyone or any shops within 40 miles who had the cutting tool to chamfer the bb facing :( and I’m out of cash this month, so bodging.

I see what you mean... I made a quick search and it doesn't seem that easy to find Italian thread bbs specially above 115mm

I’m a cheapskating bodger

I think you could include half the forum in this :)

You're probably already aware, but if you need to offset a small amount - i.e. to save messing with NDS crank clearance or Q factor - cassette spacers can be used BB spacers and they come in all thicknesses so you can probably find a 1-2mm spacer.

Example:
https://thecycleclinic.co.uk/products/wheels-manufacturing-freehub-bb-spacers-1-0mm-1-5mm-4-5mm-8-speed-to-7-speed

Lol

Ah, now, that’s a good idea. Top tip. Will report back.