Can I change it to an ISIS?
It’s on a spin bike (schwinn) and I’d sooner not mess around with it following a snapped spindle. The BB seems a large diameter.
Thanks.

Pics.?

Not at the moment I’m afraid. I’ll try and get some.
Definitely square taper drive on the crank arms.

Has to be first time anyone’s wanted to change to isis rather than get ride of it.

Should be a straight swap. Stronger axle, weaker bearings but the bearings should last if its not getting wet and muddy. Parts will be cheap. You could also swap to HT2 which might be handy if that’s what is on your other bikes. That is unless by large diameter you mean the old BMX style

Use octalink? Still available and IMO one of the best if not the best system

Ok. Just got the cranks home. The ****ing spindle is tacked to the ****ing chainring.
I cannot seem to find anything like it anywhere, I have scoured far too many exploded views on the spares websites and I’m wondering if its’ been cobbled together by a numbskull.
It has a 52-odd tooth chainring which is an issue. I can’t find a normal ISIS crankset with that size chainring. In fact, I can’t seem to cobble anything together which would suit.
It’s bollocks.

I think it’s time some pictures

Is it like this?

As long as the crank is removeable and the BB shell is standard english 68/73mm then you should be ok.

Look for some old Shimano 105 cranks or similar think they could be had in octalink variety and should be easy enough to source a 52t chainring (singlespeed/time trial would be ideal as teeth aren’t designed for shifting and no ramps either)

The BB is huge. It has spacers, which hold the spindle in place, and the bearings run inboard. I only have the spindle assembly here, I’ll post some photos.