Do you have a road frame or mountain frame?

It's a road frame,

A standard road frame is 69mm wide my frame is 73, adding spacers would only make it worse!

Road frames typically have a bottom bracket that is 68mm wide.

Yes Jim its not a typical road frame.

A Shimano road crankset with Hollowtech II axle will not work with a bottom bracket that is 73mm wide.

Easton EA90 road cranks with a Race Face Cinch 134mm spindle?

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"They're made of latex, not nitroglycerin"

To add...

There's some useful explanation on the linked discussion

https://bicycles.stackexchange.com/...h-ii-bottom-brackets

Now getting through all of this, I think your problem will be that if you fit MTB BB cups, they are a bit wider (thicker / use up more of the length of the crank spindle) than the road versions. Because they are designed to work with MTB cranks and MTB crank spindles are longer than road crank spindles.

A secondary possible problem is the MTB BB cups have longer threads (at least on the drive side) - depending on the length of internal threading in your BB they could bottom out before the mating faces of BB cup / BB dace on the frame are contacting.

A 3rd thing is the tube that pushes on between the 2 BB halves (to keep water off the spindle etc inside the frame). That may not fit - it may 'jam' / bottom out between the two BB cups as again the BB cups may protrude into the BB too far.
(You can toss that tube away and accept some moisture in the frame may get into the bearings - though Hope brgs are prretty good and being Stainless Steel are a lot more tolerant than Shimano brgs.)

Can you give a bit more info? What chainset do you have now, and why are you looking to replace it? (ie, would just new chainrings do the trick?) Do you want to run 2x or 1x? What chainring sizes are you shooting for?

Bobbajob, your comments about the spindle length wouldn't apply to an old style octalink chainset. Which is probably OEM.

I *think* that this may be the sort of thing needed. IE https://www.sjscycles.co.uk/...cket-english-thread/

I did try a GPX chainset with the Hope bottom bracket but it made the chain line too small that the front deraileur would hit the frame before changing onto the small ring, good point about the tube I had 1 mm machined of either end to stop the cups from bottoming out.

I am considering going to a one by set up. And the bike came with a octolink bottom bracket and shimano Ultegra chainset. I am going to try a 1x system on my time trial bike and see if I like it probably a 50 tooth ring.

Oh cool, if it was me I think I'd just get a 50t narrow-wide chainring (I'm guessing your chainset is not compact, hence 130mm bolt circle diameter). Wolftooth for example has them, although there may be cheaper options floating around. The only other thing you'd need is a set of single-speed chainring bolts. I actually have a similar setup on a compact Dura-ace crankset with a RaceFace chainring and it works great (albeit mine is a 68mm BB and 110 BCD).

https://www.wolftoothcomponents.com/...riant=14782015340579