any issues if i swapped out a solid 3/8 axle with a 10mm one with appropriate cones and washers etc, is there a difference in the cones where they interface with the bearing or would I be better to keep on buying the 3/8 version, I,m hoping the 10mm ones are marginally more durable being 1/2 a mm
thicker and easier to source from most bike shops.(warning!! please dont make this thread about why axles bend/break on freewheel specific hubs).

The cones can mismatch.
Expensive, but these are far stronger-
https://wheelsmfg.com/products/hub-parts/all-axles.html
I was constantly bending the rear on my "grocery getter" even though it's a Free Hub. (50 pounds in the rear baskets + my 250 at the time)
Found one of these on close out on another vendors site for about 1/2.
It's holding up.

I don't think you'll find the extra .5mm to be of any real life benefit WRT axle bending or breakage. We see enough of both with bending/breakage issues to not feel one is more durable then the other. I suspect the choice, by the hub manufacturer, has everything to do with tooling, raw material sourcing and their following specific standards then any possible performance aspect. Andy

I even found Wheelsmfg Campagnolo replacement axles better than stock .. I think they got the heat treatment right..

the quality of the part can make up for the shortcomings of the cheaper ones..

Yours may be too soft,.... I think Tullio's were a bit on the brittle hard end of the scale..







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LOL! Don't you know that every thread in this forum is primarily an open invitation for respondents to post all about themselves and whatever they want to say? But you'll fit right in: most threads here begin with a false premise.

Thanks for the replies (except ankleworks... Not helpful) the reason for moving to 10mm was also because they seem to be easier to buy from random bike shops I will just order some wheelsmith versions and be done with it.